Article

Landscape matrix and species traits mediate responses of Neotropical resident birds to forest fragmentation in Jamaica

November 2010

November 2010
80(4)

DOI:10.1890/09-0904

Authors:

Christina M Kennedy

The Nature Conservancy

Peter Marra

Smithsonian Institution

William F. Fagan

University of Maryland, College Park

Maile Catherine Neel

University of Maryland, College Park

Land cover and land use surrounding fragmented habitat can greatly impact species persistence by altering resource availability, edge effects, or the movement of individuals throughout a landscape. Despite the potential importance of the landscape matrix, ecologists still have limited understanding of the relative effects of different types of land cover and land uses on species patterns and processes in natural systems. Here we investigated whether Neotropical resident bird communities in limestone forest patches differed if they were embedded in three different human-dominated matrix types (agriculture, peri-urban development, and bauxite mining) relative to sites in continuous forest in central Jamaica. We found that species richness, community composition, and abundances were matrix-dependent, with agricultural landscapes supporting greater avian diversity and more intact community assemblages than either peri-urban or bauxite landscapes. Abundance of almost 70% of species differed in forest embedded in the different landscape matrix types. Traits related to resource use best predicted species responses, including diet guild, nest height, habitat association, and foraging strata. Insectivores, frugivores, canopy nesters, understory and canopy foragers, and forest-restricted species rarely observed in matrix habitats had lower abundances in forest fragments embedded in human-dominated matrix types than in continuous forest. In contrast, nectarivores, omnivores, granivores, ground and multi-strata nesters, ground foragers, and species regularly in matrix habitats were least sensitive to forest fragmentation. Results suggest that structure, composition, and land use disturbance regimes in matrix areas impact overall habitat quality in landscapes by potentially mediating resource availability inside as well as outside forest habitat. This study reinforces the importance of differentiating among land cover and land uses in fragmentation research and lends support to the hypothesis that resource availability may be a primary factor driving Neotropical bird responses to fragmentation.

Occupancy models disentangle the drivers of avian urban avoidance in North America's largest urban forest ☆

Article

Apr 2023
BIOL CONSERV

Urbanization dramatically modifies natural landscapes, fragments previously intact habitats, and is spreading rapidly, making it one of the leading causes of worldwide biodiversity decline. We studied the impact of urbanization on the occupancy of breeding birds in the Great Trinity Forest in Dallas, TX, the largest urban forest in the United States. The matrix of habitat surrounding the Great Trinity Forest varies from highly urbanized industrial landscapes to more rural areas. Between May 15th and July 15th of 2018, 2019, and 2020 we surveyed 404 5-ha plots for forest birds, recording 4274 observations representing 49 species. We used time-to-detection to model avian occupancy in 17 species while accounting for false absences. We found that the avian community responded to anthropogenic impacts of urbanization in the matrix in diverse ways. Urbanization intensity had the largest negative impact on avian occupancy and best explained observed patterns of urban avoidance from previous studies. Occupancy of species with low vocal frequency was negatively impacted by continuous anthropogenic noise from automobile traffic, while a broader group of species was negatively impacted by intermittent noise from airplane traffic. Occupancy exhibited both positive and negative responses to increased feral hog activity. To maintain diverse bird communities in forest fragments with a heavily urbanized matrix, it may be necessary to maintain large habitat tracts and mitigate for the indirect effects of the matrix like noise and invasive species.

Habitat quality is more important than matrix quality for bird communities in protected areas

Article

Full-text available

Mar 2018

Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta‐diversity within reserves embedded in low‐quality matrix was lower than that in high‐quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.

Environmental and anthropogenic variables influence the distribution of a habitat specialist ( Sylvilagus aquaticus ) in a large urban forest

Article

Full-text available

Jan 2023

Conservation of habitat fragments, including those embedded in an urban matrix which typically support fewer species than those in other landscape contexts, is important for combatting the global extinction crisis. Because urban avoiding species are often absent from habitat fragments within an urban matrix, studies of their distributions in these habitats are rare, and therefore the mechanisms by which species are excluded from habitat fragments within an urban matrix are poorly understood. We investigated the impacts of urbanization in the matrix (e.g., noise pollution, light pollution, invasive species) on the distribution of an urban avoiding species, the swamp rabbit (Sylvilagus aquaticus) in the largest urban forest fragment in the United States. We used the location of swamp rabbit latrines and presence‐background species distribution modeling to reveal the impacts of urbanization in the matrix on swamp rabbit distribution while accounting for spatial heterogeneity in naturally occurring environmental variables. Swamp rabbits used mature forest, heterogeneously structured forest, and moderately inundated forest, and they avoided areas of high (Sus scrofa) hog activity at our study site. Our findings provide novel information to conservation practitioners and urban planners attempting to conserve high priority species in habitat fragments as urbanization continues to spread. Feral hog activity, vegetation structure, vegetation composition, and flooding frequency drive swamp rabbit (Sylvilagus aquaticus) distribution in a large urban forest. Swamp rabbits avoid area of high feral hog (Sus scrofa) activity but are not impacted by anthropogenic noise or urbanization intensity in the nearby matrix.

RELATIONSHIPS BETWEEN FRUGIVOROUS- BIRDS AND THEIR HABITATS IN FRAGMENTED FOREST AREAS NEAR TO VILLAVICENCIO CITY, VILLAVICENCIO, META, COLOMBIA.

Article

Full-text available

Dec 2020

Rodrigo Isaac Velosa

The degradation of the Llanos foothill ecosystems is one of the biggest ecological problems in the areas surrounding the city of Villavicencio, Meta. The generation of fragments produces new conditions for the establishment of bird guilds. This study was carried out during 2017 - 2018 in areas of the campus Loma Linda at the Santo Tomas University. It was evaluated whether the forest interior, forest border and grassland areas constitute habitats that support the establishment of frugivorous birds. The key factors that affect the richness, diversity and abundance of bird species were identified, from which recommendations were made for the establishment of conservation measures. The richness of birds and their abundance was positively correlated with intermediate values of plant richness and diversity and with the presence and coverage of species of palms and lianas. The abundance and diversity of frugivorous birds were higher in border areas and lower in grasslands and forest interiors. Apparently the diversity of the habitat in border areas of fragmented lands increases the diversity of frugivorous birds through an increase in the abundance values. Artificial enrichment is recommended with different tree, shrubs and palms species planted in the edge and interior areas of the forest, and the maintenance of remaining trees and shrubs in the areas of shrub grasslands. Keywords : fragmentation, frugivorous-birds, diversity, natural regeneration.

Impacts of Amur Honeysuckle (Lonicera maackii) Removal on the Composition of Avian Assemblages in Rural Riparian Forest

Thesis

Aug 2020

Leanna DeJong

Amur honeysuckle (Lonicera maackii) was introduced to North America in the late 1880s and has since become highly invasive throughout the midwestern and northeastern United States. Amur honeysuckle-dominated habitat can be detrimental to wildlife including birds. The invasive shrub attracts generalist avian species and represents an ecological trap where manipulative habitat signals have been shown to negatively influence avian populations. Due to its detrimental effects on ecosystems, managers have invested substantial effort towards removing the shrub. Albeit many studies have explored the negative effects that Amur honeysuckle has on avian species, there is a lack of research that identifies how removing the shrub impacts birds, especially in rural areas. In order to help optimize management strategies in this regard and better understand how removing this shrub influences birds, I investigated how Amur honeysuckle removal in rural riparian forests affects the composition of avian assemblages. To accomplish this, I identified plots along the Little Miami River in Greene County, Ohio that are either invaded by or removed of Amur honeysuckle. During the 2019 peak breeding season, I performed avian point counts in order to survey avian assemblages and collected vegetation data in order to measure Amur honeysuckle prevalence and differences in habitat structure and composition among plots. I used a non-metric multidimensional scaling ordination and analysis of similarity to explore differences in avian community structure between plot types and determine whether a community difference existed. I used N-mixture and generalized linear models to explore the impact of removal on avian abundances and species richness and diversity respectively. I found that avian community composition was different between plots removed of Amur honeysuckle and plots invaded by Amur honeysuckle. The variation in avian community structure was explained, in part, by Amur honeysuckle removal. Avian species were overall more abundant in removed plots. Greater abundances of woodpeckers and species that prefer open woodlands were found in plots removed of Amur honeysuckle vs. plots invaded by Amur honeysuckle. While Amur honeysuckle removal had a positive effect on the Acadian flycatcher (Empidonax virescens), other species, i.e., the American robin (Turdus migratorius), blue-gray gnatcatcher (Polioptila caerulea), Carolina wren (Thryothorus ludovicianus), indigo bunting (Passerina cyanea), northern cardinal (Cardinalis cardinalis), northern parula (Setophaga americana), combined tufted titmouse (Baeolophus bicolor) and Carolina chickadee (Poecile carolinensis), and red-eyed vireo (Vireo olivaceus), were unaffected. Avian species diversity and richness appeared to be greater in areas removed vs. invaded by Amur honeysuckle. These findings provide insight to land managers in southwest Ohio regarding how the removal of Amur honeysuckle in rural riparian forests impacts avian community composition. Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=osu1598006298750454

Sampling design may obscure species–area relationships in landscape‐scale field studies

Article

Full-text available

Oct 2019
ECOGRAPHY

We investigated 1) the role of area per se in explaining anuran species richness on reservoir forest islands, after controlling for several confounding factors. We also assessed 2) how sampling design affects the inferential power of island species–area relationships (ISARs) aiming to 3) provide guidelines to yield reliable estimates of area‐induced species losses in patchy systems. We surveyed anurans with autonomous recording units at 151 plots located on 74 islands and four continuous forest sites at the Balbina Hydroelectric Reservoir landscape, central Brazilian Amazonia. We applied semi‐log ISAR models to assess the effect of sampling design on the fit and slope of species–area curves. To do so, we subsampled our surveyed islands following both a 1) stratified and 2) non‐stratified random selection of 5, 10, 15, 20 and 25 islands covering 1) the full range in island size (0.45–1699 ha) and 2) only islands smaller than 100 ha, respectively. We also compiled 25 datasets from the literature to assess the generality of our findings. Island size explained ca half of the variation in species richness. The fit and slope of species–area curves were affected mainly by the range in island size considered, and to a very small extent by the number of islands surveyed. In our literature review, all datasets covering a range of patch sizes larger than 300 ha yielded a positive ISAR, whereas the number of patches alone did not affect the detection of ISARs. We conclude that 1) area per se plays a major role in explaining anuran species richness on forest islands within an Amazonian anthropogenic archipelago; 2) the inferential power of island species–area relationships is severely degraded by sub‐optimal sampling designs; 3) at least 10 habitat patches spanning three orders of magnitude in size should be surveyed to yield reliable species–area estimates in patchy systems.

Spatial Variation in Density of White-footed Mice Along Edges in Fragmented Habitat

Article

Jan 2018

The influence of forest fragmentation and associated habitat edges differentially affects forest-dependent organisms, particularly when certain species are able to use resources from surrounding matrix habitats. The white-footed mouse is a forest habitat generalist and is known to disperse among adjoining farmland habitats, including agricultural matrix, in fragmented agro-ecosystems. However, little is known about spatial variation in population density within adjoining farmland habitats or how this relationship varies seasonally. In addition quantifying the extent to which white-footed mice use agricultural matrix as habitat is important for inferring potential ecosystem services (predation of weed seed and waste grain) rendered within row-crop fields. We used spatially explicit capture-recapture models to estimate density of white-footed mice along a gradient of patch (forest fragment) interior to matrix (crop field) interior that spanned fragmented habitat edges. Spatial variation in population density within adjoining habitats was related to the distance from habitat edge, and the magnitude of this relationship (edge effect) varied among seasons and crop cycles within the agricultural matrix. Within-field densities were greater during periods of summer crop growth relative to spring crop emergence or following fall crop harvest. Populations of white-footed mice in forest fragments appear to seasonally spill over from patch habitat into surrounding agricultural matrix. Acquisition of resources from surrounding agricultural matrix may contribute to the inverse density-area relationship observed for white-footed mice within forested habitat in fragmented landscapes. Furthermore, seasonal foraging within matrix habitat likely provides weed seed predation ecosystem services in row-crop fields.

Avian Ecology in Latin American Cityscapes

Book

Jan 2017

This book gathers a representative sample of the relevant knowledge related to the ecology, behavior, and conservation of birds in urban Latin America. Latin America is one of the most biodiverse regions of the world, yet it is still understudied. Although it concentrates most of its population in rapidly growing cities under considerable economic, social, and environmental disparity, the study of the effects that urbanization has on biodiversity in Latin America is still insufficient. Among the best-studied wildlife groups, birds have been widely used as bioindicators in urban areas. Going from general to specific information regarding avian communities, populations, behavior, threats, and conservation issues, this book describes the state-of-the-art of avian urban ecology in the region. Such knowledge will hopefully promote the regional consolidation of the field and encourage future mechanistic studies that untangle the recorded patterns in order to have the required information to bridge the gap between evidence-based knowledge and practice in urban systems. Thus, the information included in this document will allow scientists, students, and even decision takers to relate with the current knowledge and gaps related to the topic, providing perspective for future studies and actions.

What’s New? An Updated Review of Avian Ecology in Urban Latin America

Chapter

Nov 2017

Among human activities, urbanization represents one of the most worrisome for biodiversity due to the intensity and long-term effects in the place where a city develops, as well as their indirect effect in its area of influence. Birds are one of the most studied groups to assess the impacts that urbanization has on biodiversity, but there is a lag in the knowledge of highly biodiverse regions like Latin America. This region is the most diverse in avian species, but at the same time is one of the most affected by poverty, social inequality, and population growth, representing a priority for studying urban bird responses to urbanization. In this chapter, we compare results of studies of urban birds in Latin American cities published in recent years with an earlier regional review. We found more than one-third of publications in the last six years than in the previous 35 years; however, there is still a bias in the knowledge toward most populated countries, while urban Central America remains understudied. Although there is a lack of information on the mechanistic processes molding urban avian communities, there are important advances in ecological topics, as novel resource use, urban noise, and urban avian diseases. We urge scientists of Latin American latitudes to join efforts in the understanding of avian communities in urban areas. Results of evidence-based studies ought to be communicated to decision-makers to generate strategies that improve urban management and planning.

Birds from Urban Latin America, Where Economic Inequality and Urbanization Meet Biodiversity

Chapter

Nov 2017

Following a massive migration toward cities, more than half of the total human population is now urban. Given the unbalanced metabolism of urban systems, urbanization has been recognized to be a major ecological driver with worrisome consequences at different spatial and temporal scales. Such an environmental issue has drawn the attention of ecologists from across the globe since the late 1990s, when urban ecology consolidated as a discipline. Although urban ecology has developed importantly in the last three decades, our comprehension of the effects of urbanization on wildlife communities is heavily biased toward developed countries, most of which are located in temperate regions. Woefully, there is a dearth of knowledge from highly biodiverse areas with increasing urbanization rates and major urban agglomerations. Latin America is not an exception, with most of its population in rapidly growing urban centers. Given that the region concentrates important biodiverse areas in a scenario of considerable economic and social disparity, understanding the effects that urbanization has on wildlife species is of special concern. Even though ecological studies performed in urban Latin America started in the 1970s, urban ecology in the region is still in the process of consolidation, with birds being the most studied group. Several ecological patterns hold in urban Latin America when contrasted with those from other regions; yet, important differences have been identified, making evident the need to understand the response of wildlife species in the region. In this book, we gathered regional experts to set the state-of-the-art of bird studies in urban Latin America. Starting with an updated review, the book transits across topics such as urban bird species richness, composition, abundance, demography, population dynamics, behavior, threats, and conservation, as well as their relationships with ‘green’ and ‘gray’ infrastructures. After reviewing the specific topics with information from across the globe, each chapter contrasts the global findings with those from Latin America, identifying knowledge gaps and research needs to suggest future directions. The gathered information sets the foundation for the study of birds in urban Latin America, hopefully promoting the consolidation of the field in the region and encouraging future mechanistic studies that untangle the recorded patterns to have the required information to bridge the gap between evidence-based knowledge and practice in urban systems.

Spatiotemporal variations in migratory bird diversity and abundance along the coast of Gochang getbol

Article

Full-text available

May 2024
PLOS ONE

Tidal flats provide critical habitat for migratory waterbird species; however, populations of migratory waterbirds have significantly declined due to tidal flat loss and degradation caused by human activities, particularly in Asia. Gochang getbol is one of tidal flats located on the southwest coast of South Korea and a center of clam production. Using bird monitoring data collected at five zones (zone1 to zone5) established across Gochang getbol and near coastal area, we examined distribution patterns of migratory bird diversity and conservation-related species along the coast of Gochang getbol. The intensity of human activity ‒ mudflat culture (mostly bivalve) and aquaculture was relatively high at zone2 and zone3, occupying > 30% of 2km circular area surrounding most sample points of these zones. Zone1 and particularly zone4 contained more natural/semi-natural habitats (less disturbed mudflats and wetlands) and zone5 had smallest mudflat than others. Shannon diversity, species richness, and abundance of migratory birds differed between zones (Anova test, P ≤ 0.02) except Shannon diversity in winter. In fall, all values were higher at zone4 than zone3 and zone5. In winter, zone1 showed greatest species richness and higher abundance than zone2, zone3, and zone5. In spring, while most differences were found between zone4 and zone5, abundance at zone4 was somewhat higher than zone2. The results from the fourth corner analysis indicated that abundance of species foraging at mudflat level was positively associated with zone1 (winter) but negatively with zone3 (fall). Sandpipers were positively associated with zone4. Abundance distribution maps of conservation-related species, created by inverse distance-weighted interpolation modeling, also showed high abundance of most conservation-related species at zone4 and 1. The findings of our study suggest the importance of natural/semi-natural habitat, and the possible link between human activity and distribution patterns of migratory birds in Gochang getbol. While we need further investigation on direct response of migratory birds to human activity, areas with low human activity with more natural/semi-natural habitat, e.g., zone4 and zone1 may be crucial for the conservation of migratory birds.

3D habitat structure drives avian functional and trait diversity across North America

Preprint

Full-text available

May 2024

Understanding how 3D habitat structure drives biodiversity patterns is key to predicting how habitat alteration and loss will affect species and community-level patterns in the future. To date, few studies have contrasted the effects of three-dimensional (3D) habitat composition with those of 3D habitat configuration on biodiversity, with existing investigations often limited to measures of taxonomic diversity (i.e., species richness). Here, we examined the influence of Light Detecting and Ranging (LiDAR)-derived 3D habitat structure–both its composition and configuration–on multiple facets of bird diversity. Specifically, we used data from the National Ecological Observatory Network (NEON) to test the associations between eleven measures of 3D habitat structure and avian species richness, functional and trait diversity, and phylogenetic diversity. We found that 3D habitat structure was the most consistent predictor of avian functional and trait diversity, with little to no effect on species richness or phylogenetic diversity. Functional diversity and individual trait characteristics were strongly associated with both 3D habitat composition and configuration, but the magnitude and the direction of the effects varied across the canopy, subcanopy, midstory, and understory vertical strata. Our findings suggest that 3D habitat structure influences avian diversity through its effects on traits. By examining the effects of multiple aspects of habitat structure on multiple facets of avian diversity, we provide a broader framework for future investigations on habitat structure. Posted on 24 May 2024 | The copyright holder is the author/funder. All rights reserved. No reuse without permission. | https://doi.org/10.22541/au.171654107.71445289/v1 | This is a preprint and has not been peer-reviewed. Data may be preliminary.

Assessing bird habitat occupancy from gradient‑based landscape metrics and principal polar spectral indices in the colombian andean region

Article

Feb 2023
LANDSCAPE ECOL

Assessing bird habitat occupancy from gradient-based landscape metrics and principal polar spectral indices in the colombian andean region

Article

Full-text available

Feb 2023
LANDSCAPE ECOL

Context The patch-mosaic model (PMM) is the most common way to describe the landscape in ecological research. Despite this, the gradient model (GM) was proposed as a more accurate representation of the heterogeneity of landscapes; however, little has been explored on the behavior and performance of continuous variables and surface-based metrics from GM under different analytical scenarios. Objectives We address the question: which landscape metrics, patch-based or surface-based, best explain habitat occupancy patterns of six bird species with different ecological preferences? Methods We generated detection histories for six bird species in a fragmented Andean landscape from Colombia. We obtain patch-based metrics from a land cover classification and surface-based metrics from the principal polar spectral indices (PPSi) to describe the landscape. Finally, we fitted dynamic occupancy models using variables derived from landscape models and compared their performance using quasi-AIC for each species. Results We obtained 909 detections for the six selected bird species. We found that PPSi and surface-based metrics were more informative when assessing occupancy patterns for five of the six species studied. In addition, surface-based metrics allowed to detect interspecific differences between species beyond an affinity for a particular cover type. Conclusions Surface-based metrics can be an alternative for assessing species response to landscape heterogeneity, particularly those that may be more sensitive to fine-scale changes in vegetation cover. However, there is no single “best” model to describe the landscape for all cases. PPSi can be very useful for land cover analysis in landscape ecology studies as an alternative to more popular vegetation indices.

Matrix quality determines the strength of habitat loss filtering on bird communities at the landscape scale

Article

Full-text available

Aug 2022
J APPL ECOL

Habitat loss represents a major threat to biodiversity, however, the modulation of its effects by the nonhabitat matrix surrounding habitat patches is still undervalued. The landscape matrix might change community assembly in different ways. For example, low‐quality matrices can accentuate environmental filtering by reducing resource availability and/or deteriorating abiotic conditions but they may also excessively limit dispersal of organisms and make communities more prone to ecological drift. To understand how matrix quality modulates the effects of habitat loss, we quantified the relative importance of environmental filter and ecological drift in bird communities across more local (400 m buffer around sampling sites) and broader (2 km focal landscapes) gradients of habitat loss embedded in low‐ and high‐quality matrices. We used a trait‐based approach to understand habitat loss filtering effects on occurrences of forest specialist and habitat generalist birds. We found that low‐quality matrices, composed mainly of low‐productive pasturelands, increased the severity of habitat loss filtering effects for forest specialist birds, but only at the landscape scale. Bird occurrences were in general higher in high‐quality matrices, that is, more heterogeneous and with low‐contrasting edges, indicating the role of the matrix quality in attenuating species extinction risks at the landscape scale, probably due to mass effect. Moreover, forest specialists presented a strong negative response to habitat loss filtering across different functional traits, while generalists presented a high variability in traits response to habitat loss. Synthesis and applications: We raised evidence in supporting that landscape habitat loss filtering may be relaxed or reinforced depending on the quality of the matrix, evidencing that matrix quality has a strong impact in modulating community assembly processes in fragmented landscapes. In practical terms, it means that improving matrix quality may help in maintaining the high diversity of birds even without any increase in native forest cover.

Complex landscapes stabilize farm bird communities and their expected ecosystem services

Article

Full-text available

Jan 2022
J APPL ECOL

Birds play many roles within agroecosystems including as consumers of crops and pests, carriers of pathogens and beloved icons. Birds are also rapidly declining across North America, in part due to agricultural intensification. Thus, it is imperative to identify how to manage agroecosystems to best support birds for multi‐functional outcomes (e.g. crop production and conservation). Both the average amounts of services/disservices provided and their temporal stability are important for effective farm planning. Here, we conducted point count surveys for 4 years across 106 locations on 27 diversified farms in Washington and Oregon, USA. We classified birds as ecosystem service or disservice providers using indices spanning supporting, regulating, provisioning and cultural services/disservices. We then examined service/disservice index pairwise correlations and assessed the relative importance of local, farm and landscape complexity on the average and temporal stability of avian service/disservice provider indices. Generally, service provider indices (production benefitting birds, grower appreciation and conservation scores) were positively correlated with each other. Foodborne pathogen risk, grower disapproval and identity/iconic value indices were also positively correlated with each other. However, the crop damaging bird index generally had low correlations with other indices. Farms that implemented more conservation‐friendly management practices generally had higher average service provider indices, but farm management did not impact disservice provider indices, except for grower disapproval. Average disservice provider indices were lower on farms in complex landscapes. Local vertical vegetation complexity tended to increase the temporal stability of service provider indices but did not affect the disservice provider indices. Greater landscape complexity was generally associated with increased temporal stability of service and disservice provider indices. Increased landscape complexity may stabilize bird communities by increasing bird community evenness, which in turn, positively predicted temporal stability of all service/disservice provider indices. Policy implications. Our results suggest that farmers can effectively manage their farms to harness ecosystem services from birds through farm diversification. Disservices provided by birds, however, appear to be most negatively impacted by landscape‐level complexity. Thus, greater incentives for farmers to increase semi‐natural cover at the landscape scale are likely necessary to achieve multifunctional outcomes for conservation and agriculture.

Impact of Vegetation Cover Structure on Birds' Community at Tianfu National Wetland Park in Jiangsu Kunshan, China

Preprint

Full-text available

Sep 2021

Background: Vegetation cover has an essential role in wetland habitats in controlling avian populations throughout the world. The vegetation cover structure in grassland systems varies dramatically among seasons on the same sites. Variation in vegetation cover-abundance richness and diversity has been studied through one hundred forty-seven quadrate samples during summer and autumn, 2019, winter, and spring 2020. Avian species richness and diversity were recorded during the same period. Results: The correlation analysis results confirmed that: (1) there was no apparent seasonal difference in the abundance of vegetation cover while avian abundance was statistically different. (2) Plant abundance in summer was positively correlated with the number of avian, while in autumn it was negatively correlated. Plant and avian abundance at the genus level showed a positive correlation while maintaining a negative correlation at the species level (p < 0.05). However, during summer and autumn, a strong linear relationship exists between vegetation coverage and avian. The Shannon diversity index and Simpson diversity index have a positive linear relationship between vegetation coverage and avian families and genera. Conclusions: We conclude that vegetation coverage richness significantly impact avian communities. We suggest further research into the relationship between other biological communities and farming practices in the wetlands.

Impact of Vegetation Cover Structure on Birds' Community at Tianfu National Wetland Park in Jiangsu Kunshan, China

Preprint

Full-text available

Sep 2021

Vegetation cover has an essential role in wetland habitats in controlling avian populations throughout the world. The vegetation cover structure in grassland systems varies dramatically among seasons on the same sites. Variation in vegetation cover-abundance richness and diversity has been studied through one hundred forty-seven quadrate samples during summer and autumn, 2019, winter, and spring 2020. Avian species richness and diversity were recorded during the same period. Meanwhile, correlation analysis results confirmed that: (1) there was no apparent seasonal difference in the abundance of vegetation cover while avian abundance was statistically different. (2) Plant abundance in summer was positively correlated with the number of avian, while in autumn it was negatively correlated. Plant and avian abundance at the genus level showed a positive correlation while maintaining a negative correlation at the species level (p < 0.05). However, during summer and autumn, a strong linear relationship exists between vegetation coverage and avian. The Shannon diversity index and Simpson diversity index have a positive linear relationship between vegetation coverage and avian families and genera. Therefore, we conclude that vegetation coverage and richness significantly impact avian communities. We suggest further research into the relationship between other biological communities and farming practices in the wetlands

Effects of Soil Management Practices on Soil Physical Properties and Water Cycle in a Multifactorial Field Experiment

Chapter

Sep 2021

In the last few decades, Bengaluru’s rapid urban expansion and associated population growth brought about profound changes in farming practices, reflected in an increase in irrigated land compared to rainfed land and a growing use of mineral fertilizers. Since it is not clear how intensification of land use due to urbanisation is affecting physical soil properties and field water cycle, we attempt to clarify this at two experimental sites established at the University of Agricultural Sciences Bangalore (UASB). The results show higher bulk densities, lower air capacities, and lower saturated hydraulic conductivity (Ksat) values in the rainfed field compared to the irrigated field. Soil moisture was observed to be higher in deeper layers of several plots with low N-level treatments in both experiments. However, it was not significant in other plots. Further statistical investigations and comparisons especially of model simulations are required to assess the effect of land use intensifications. Here the experimental approach and some preliminary results are presented.

Biodiversity of Birds Along the Rural–Urban Interface of the Indian Megacity Bengaluru

Chapter

Sep 2021

Urban areas are increasing in number and extent worldwide. Few other anthropogenic land uses alter landscapes in a more persistent fashion; however, the effects of urbansiation on biodiversity remain poorly studied. Here, we studied bird communities along the rural–urban interface of the Indian megacity Bengaluru. Birds were assessed with point counts on 36 vegetable-growing farms situated within three urbanisation stages (urban, peri-urban and rural) and across three seasons (monsoon, winter, summer). We recorded 4617 individuals comprising 149 species. Bird richness was highest in peri-urban farms and lowest in rural areas, while urban areas were intermediate. Bird abundance did not differ among urbanisation stages. Increasing amount of impervious area in the surrounding landscape reduced bird richness and abundance, with the greatest effect up to 20% impervious area, levelling off beyond this threshold. Bird community composition on urban farms was distinct from rural areas, while peri-urban areas supported species from both species pools. In conclusion, urbanisation and particularly impervious areas threaten Bengaluru’s bird diversity. Peri-urban areas that mark the transition from rural to urban areas are hotspots of bird diversity. City planning should aim to retain green areas and avoid densification, particularly in the peri-urban interface where urbanisation happens most rapidly.

Effects of landscape context on mammal richness in the urban forest mosaic of EThekwini Municipality, Durban, South Africa

Article

Full-text available

Mar 2020

The loss and fragmentation of natural habitats is a major threat to biodiversity globally. In fragmented landscapes, species are not only affected by patch-level attributes but also by the influence of the whole mosaic of landscape elements surrounding habitat patches. Therefore, it is important to understand the simultaneous effects of local and landscape-level attributes on biodiversity. In this study, we determined the influence of landscape context on species richness of forest mammals in an urban-forest mosaic of the EThekwini Municipality Area, Durban, South Africa. We determined presence/absence of mammals in 28 patches using remote-triggered camera traps over two sampling periods. We applied generalised linear modelling within an information-theoretic framework to quantify the effects of within-patch, isolation, matrix, and landscape level attributes on species richness. The results showed the importance of landscape context for occurrence patterns of mammals in fragmented landscapes. In particular, they showed that patch size, shape complexity, habitat amount in the immediate environment, habitat proximity and road density were the most important factors influencing mammalian richness patterns. Overall, the results stressed the importance of habitat area (patch size, habitat amount in the immediate environment, and habitat proximity) and its spatial configuration to faunal preservation and suggest that management efforts in this landscape should be aimed at protecting fragments from further loss and disturbance and matrix improvement to increase landscape connectivity.

Predicting Bird Guilds Using Vegetation Composition and Structure on a Wild and Scenic River in Arizona

Article

Sep 2020

Riparian areas are among the most ecologically diverse terrestrial ecosystems but make up <2% of landscape area in southwestern USA. Many species of resident and neotropical migratory birds utilize riparian habitats for breeding, foraging, and nesting. We quantified vegetation composition and structure to predict bird guilds on Wild and Scenic portions of the Verde River, Arizona. We grouped plant species into guilds based on similar functional traits to describe composition. We surveyed birds during the breeding and migrating season to determine abundance and categorized species into guilds using preferences of breeding habitat, foraging substrate, and nest placement. Riparian obligate and facultative breeding guilds were most common. Both vegetation composition and structure were useful predictors of birds. Vegetation structure was most complex in gallery riparian forest. Abundance of riparian-obligate birds in the breeding guild were positively associated with vegetation structure of dense, multi-canopy canopy and tall trees. Abundance of most bird guilds were positively associated with composition of tall trees (Populus fremontii, Salix gooddingii) and drought tolerant shrubs (Prosopis velutina, Celtis reticulata). Our findings show complex riparian habitat important to wildlife is created by both composition and structure of near-stream vegetation that is tied to hydrology and sensitive to flow change.

Avifauna of the region of the Volta Grande Hydroelectric Power Plant in Southeast Brazil

Article

Full-text available

Jun 2020

The Volta Grande region in the Brazilian state of Minas Gerais is classified as of “High Biological Importance” for the conservation of birds in the state. Despite this, the avifauna of the region has yet to be adequately sampled, as evidenced by the few papers on the region in ornithological literature. The results of an avifaunal inventory conducted between March 2013 and January 2014 in five sites located throughout the region of the Volta Grande Hydroelectric Power Plant in Southeast Brazil are presented. Point-counts, ad libitum observations and mist-nets recorded 224 species for the region, with insectivorous and omnivorous being the predominant feeding habits. Species that are “independent” of forest habitats comprised 52% of the recorded species. Three species are endemics of the Cerrado, 83 are migratory and 32 are under some degree of threat of extinction. These findings demonstrate that the region of the Volta Grande Hydroelectric Power Plant is important for bird conservation. Additional inventories, adequate management plans and public policies aimed the preserving species are needed for more effective conservation of the biodiversity of the studied region.

Effects of a regenerating matrix on the survival of birds in tropical forest fragments

Article

Full-text available

Mar 2020

Background Vast areas of lowland neotropical forest have regenerated after initially being cleared for agricultural purposes. The ecological value of regenerating second growth to forest-dwelling birds may largely depend on the age of the forest, associated vegetative structure, and when it is capable of sustaining avian demographics similar to those found in pristine forest. Methods To determine the influence of second growth age on bird demography, we estimated the annual survival of six central Amazonian bird species residing in pristine forest, a single 100 and a single 10 ha forest fragment, taking into consideration age of the surrounding matrix (i.e. regenerating forest adjacent to each fragment) as an explanatory variable. Results Study species exhibited three responses: arboreal, flocking and ant-following insectivores ( Willisornis poecilinotus , Thamnomanes ardesiacus and Pithys albifrons ) showed declines in survival associated with fragmentation followed by an increase in survival after 5 years of matrix regeneration. Conversely, Percnostola rufifrons , a gap-specialist, showed elevated survival in response to fragmentation followed by a decline after 5 years of regeneration. Lastly, facultative flocking and frugivore species ( Glyphorynchus spirurus and Dixiphia pipra , respectively) showed no response to adjacent clearing and subsequent regeneration. Conclusions Our results in association with previous studies confirm that the value of regenerating forest surrounding habitat patches is dependent on two factors: ecological guild of the species in question and second growth age. Given the rapid increase in survival following succession, we suggest that the ecological value of young tropical forest should not be based solely on a contemporary snapshot, but rather, on the future value of mature second growth as well.

Highly diversified crop-livestock farming systems reshape wild bird communities

Data

Oct 2019

Agricultural intensification is a leading threat to bird conservation. Highly diversified farming systems that integrate livestock and crop production might promote a diversity of habitats useful to native birds foraging across otherwise-simplified landscapes. At the same time, these features might be attractive to nonnative birds linked to a broad range of disservices to both crop and livestock production. We evaluated the influence of crop-livestock integration on wild bird richness and density along a north-south transect spanning the U.S. West Coast. We surveyed birds on 52 farms that grew primarily mixed vegetables and fruits alone or integrated livestock into production. Crop-livestock systems harbored higher native bird density and richness relative to crop-only farms, a benefit more pronounced on farms embedded in nonnatural landscapes. Crop-livestock systems bolstered native insectivores linked to the suppression of agricultural pest insects but did not bolster native granivores that may be more likely to damage crops. Crop-livestock systems also significantly increased the density of nonnative birds, primarily European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus) that may compete with native birds for resources. Models supported a small, positive correlation between nonnative density and overall native bird density as well as between nonnative density and native granivore density. Relative to crop-only farms, on average , crop-livestock systems exhibited 1.5 times higher patch richness, 2.4 times higher density of farm structures, 7.3 times smaller field sizes, 2.4 times greater integration of woody crops, and 5.3 times greater integration of pasture/hay habitat on farm. Wild birds may have responded to this habitat diversity and/or associated food resources. Individual farm factors had significantly lower predictive power than farming system alone (change in C statistic information criterion (DCIC) = 80.2), suggesting crop-livestock systems may impact wild birds through a suite of factors that change with system conversion. Collectively, our findings suggest that farms that integrate livestock and crop production can attract robust native bird communities , especially within landscapes devoted to intensified food production. However, additional work is needed to demonstrate persistent farm bird communities through time, eco-physiological benefits to birds foraging on these farms, and net effects of both native and non-native wild birds in agroecosystems.

Highly diversified crop–livestock farming systems reshape wild bird communities

Article

Full-text available

Dec 2019
ECOL APPL

Agricultural intensification is a leading threat to bird conservation. Highly diversified farming systems that integrate livestock and crop production might promote a diversity of habitats useful to native birds foraging across otherwise‐simplified landscapes. At the same time, these features might be attractive to nonnative birds linked to a broad range of disservices to both crop and livestock production. We evaluated the influence of crop–livestock integration on wild bird richness and density along a north‐south transect spanning the U.S. West Coast. We surveyed birds on 52 farms that grew primarily mixed vegetables and fruits alone or integrated livestock into production. Crop–livestock systems harbored higher native bird density and richness relative to crop‐only farms, a benefit more pronounced on farms embedded in nonnatural landscapes. Crop–livestock systems bolstered native insectivores linked to the suppression of agricultural pest insects but did not bolster native granivores that may be more likely to damage crops. Crop–livestock systems also significantly increased the density of nonnative birds, primarily European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus) that may compete with native birds for resources. Models supported a small, positive correlation between nonnative density and overall native bird density as well as between nonnative density and native granivore density. Relative to crop‐only farms, on average, crop–livestock systems exhibited 1.5 times higher patch richness, 2.4 times higher density of farm structures, 7.3 times smaller field sizes, 2.4 times greater integration of woody crops, and 5.3 times greater integration of pasture/hay habitat on farm. Wild birds may have responded to this habitat diversity and/or associated food resources. Individual farm factors had significantly lower predictive power than farming system alone (change in C statistic information criterion (ΔCIC) = 80.2), suggesting crop–livestock systems may impact wild birds through a suite of factors that change with system conversion. Collectively, our findings suggest that farms that integrate livestock and crop production can attract robust native bird communities, especially within landscapes devoted to intensified food production. However, additional work is needed to demonstrate persistent farm bird communities through time, ecophysiological benefits to birds foraging on these farms, and net effects of both native and nonnative wild birds in agroecosystems.

The traits that predict the magnitude and spatial scale of forest bird responses to urbanization intensity

Article

Full-text available

Jul 2019
PLOS ONE

As humans continue moving to urban areas, there is a growing need to understand the effects of urban intensification on native wildlife populations. Forest species in remnant habitat are particularly vulnerable to urban intensification, but the mechanisms behind these effects are poorly understood. An understanding of how species traits, as proxies for mechanisms, mediate the effects of urban intensification on forest species can help fill this knowledge gap. Using a large point count dataset from the Second Pennsylvania Breeding Bird Atlas, we tested for the effects of species traits on the magnitude and spatial scale of the responses of 58 forest bird species to urbanization intensity in landscapes surrounding count locations. Average urbanization intensity effect size across species was -0.36 ± 0.49 (SE) and average scale of effect of urbanization intensity was 4.87 ± 5.95 km. Resident forest bird species that are granivorous or frugivorous, cavity-nesting, and have larger clutch sizes and more fledglings per clutch had more positive associations with increasing urbanization intensity in landscapes. In addition, the effect of urbanization intensity on forest birds manifested most strongly at larger spatial scales for granivorous, frugivorous, or omnivorous species that are cavity-nesting, have larger clutch sizes and longer wingspans, and flock in larger numbers. To our knowledge, the present study represents the first direct tests of the effects of species traits on both the magnitude and spatial scale of the effect of urbanization on forest birds, as well as the first evidence that migratory status, clutch size, wingspan, and fledglings per clutch are important determinants of the responses of forest birds to urbanization. We discuss the possible mechanisms underlying our results and their implications for forest bird conservation in urbanizing landscapes.

Organic farms conserve a dung beetle species capable of disrupting fly vectors of foodborne pathogens

Article

Jul 2019

Matrix type and landscape attributes modulate avian taxonomic and functional spillover across habitat boundaries in the Brazilian Atlantic Forest

Article

Full-text available

Jun 2019

Land use intensification drives biodiversity loss worldwide. In heterogeneous landscape mosaics, both overall forest area and anthropogenic matrix structure induce changes in biological communities in primary habitat remnants. However, community changes via cross‐habitat spillover processes along forest‐matrix interfaces remain poorly understood. Moreover, information on how landscape attributes affect spillover processes across habitat boundaries are embryonic. Here, we quantify avian α and β‐diversity (as proxies of spillover rates) across two dominant types of forest‐matrix interfaces (forest‐pasture and forest‐eucalyptus plantation) within the Atlantic Forest biodiversity hotspot in southeast Brazil. We also assess the effects of anthropogenic matrix type and landscape attributes (forest cover, edge density and land‐use diversity) on bird taxonomic and functional β‐diversity across forest‐matrix boundaries. Alpha taxonomic richness was higher in forest edges than within both matrix types, but between matrix types, it was higher in pastures than in eucalyptus plantations. Although significantly higher in forests edges than in the adjacent eucalyptus, bird functional richness did not differ between forest edges and adjacent pastures. Community changes (β‐diversity) related to species and functional replacements (turnover component) were higher across forest‐pasture boundaries, whereas changes related to species and functional loss (nested component) were higher across forest‐eucalyptus boundaries. Forest edges adjacent to eucalyptus had significant higher species and functional replacements than forest edges adjacent to pastures. Forest cover negatively influenced functional β‐diversity across both forest‐pasture and forest‐eucalyptus interfaces. We show the importance of matrix type and the structure of surrounding landscapes (mainly forest cover) on rates of bird assemblage spillover across forest‐matrix boundaries, which has profound implications to biological fluxes, ecosystem functioning and land‐use management in human‐modified landscapes. This article is protected by copyright. All rights reserved.

Interactive effects of land use, grazing and environment on frogs in an agricultural landscape

Article

Sep 2019
AGR ECOSYST ENVIRON

Improved management of human-modified landscapes must be part of global efforts to combat biodiversity loss. We aimed to identify which land management types and environmental factors influenced the use of grazing landscapes by frogs. We surveyed frog assemblages in remnant vegetation, four different paddock types (pasture, linear planting, coarse woody debris addition and fence), and two grazing regimes (continuous and rotational). Frogs were surveyed using pitfall and funnel traps in twelve grazing farms in south-eastern Australia. We found that grazed agricultural landscapes provide important habitats for a variety of species of frogs and that frog assemblages were influenced by both farm management type and environmental variables, and their interactions. Total frog abundance increased with proximity to water more strongly in remnants compared to paddocks. This difference in response may be due to different traits and behaviours of frogs in remnants compared to frogs in open paddocks. Rare frog species richness and abundance of a common species (Limnodynastes tasmaniensis) increased with taller ground cover in remnants but no such relationship occurred in paddocks. Different types of predation risk in remnants compared to paddocks may result in greater ground cover shelter requirements in remnants, as vegetation structure can strongly influence predation. Total frog species richness increased more rapidly with higher rainfall in continuously grazed versus rotationally grazed farms. Higher rainfall was associated with taller ground cover. Continuously grazed farms had shorter average ground cover than rotationally grazed farms and the increased ground cover height associated with more rain may bring ground cover to a height better able to provide shelter and reduce desiccation risk for frogs. Our study highlights the importance of both land management practices and environmental conditions and their interaction in shaping frog assemblages. Improved frog biodiversity conservation may be achieved in grazing landscapes by retaining patches of remnant vegetation, maintaining water bodies such as farm dams, and maintaining tall ground cover within vegetation remnants.

Countryside Biogeography: the Controls of Species Distributions in Human-Dominated Landscapes

Article

Full-text available

Jun 2019

Purpose of Review Countryside biogeography seeks to explain the distribution of wildlife in human-dominated landscapes. We review the theoretical and empirical progress towards this goal, assessing what forces control the presence, abundance, and richness of species in anthropogenic and natural habitats, based on characteristics of the landscape and the species themselves. Recent Findings Recent modifications of species-area relationships that incorporate multiple habitat types have improved understanding of species diversity in countryside landscapes. Attempts to understand why species affiliate with human-modified habitats have been met with only partial success. Though traits frequently explain associations with human-modified habitats within studies, explanatory traits are only rarely shared between studies, regions, or taxa. Nonetheless, greater attention to the regional and climatological context of countryside landscapes has uncovered that (i) species that associate with human-modified habitats within landscapes tend to occur primarily in warm and/or dry biomes at regional scales and (ii) species that rely exclusively on human-modified habitats in cool or wet regions may be restricted to natural habitats in warm or dry regions. Summary There remains a pressing need to determine how biodiversity can best be supported within landscapes to preserve nature and maximize ecosystem service benefits for humans. Future work in countryside biogeography must identify how land-use change interacts with other global stressors (e.g., climate change), determine how extinction debt and population sinks influence diversity, quantify the cascading effects of community changes on ecosystem services, and elucidate the evolutionary history and origins of species that today dwell in the countryside.

Multiscale analysis of canopy arthropod diversity in a volcanically fragmented landscape

Article

Full-text available

Apr 2019

Habitat fragmentation resulting in habitat loss and increased isolation is a dominant driver of global species declines. Habitat isolation and connectivity vary across scales, and understanding how connectivity affects biodiversity can be challenging because the relevant scale depends on the taxa involved. A multiscale analysis can provide insight in biodiversity patterns across spatial scale when information on dispersal ability is not available, in particular for community‐level studies focusing on multiple taxa. In this study, we examine the relationship between arthropod diversity, patch area, and connectivity using a multiscale approach. We make use of a natural experiment on Hawai‘i Island, where historic volcanic activity has transformed contiguous native forests to lava matrix and discrete forest patches. This landscape of patches has persisted for 150 yr, and we selected 10,000 ha consisting of 863 patches to analyze landscape connectivity using a graph theory approach. We collected arthropod samples from Metrosideros polymorpha tree canopies in 34 forest patches during multiple years. We analyzed the relationship of arthropod diversity with area, as well as with connectivity across increasing scales, or dispersal threshold distances. In contrast to well‐established ecological theory as well as prior work on birds and fungi in this system, we did not find support for a canonical species–area relationship. Next, we calculated connectivity across spatial scales and found lower Shannon diversity with higher connectivity at small scales, but no effect at increased dispersal threshold distances. We examined the landscape structure and found all habitat patches connected into three subnetworks at a 350 m threshold distance. All patches were connected at 700 m threshold distance, indicating structural dispersal limitation only at small scales. Our findings suggest that canopy arthropods are not dispersal limited at scales shown to impact both soil fungi and birds in this system. Instead, Hawaiian canopy arthropods may perceive the landscape as a connected area where discrete forest patches and the early‐successional matrix contribute resources that vary spatially with regard to habitat quality. We argue for the utility of multiscale approaches, and the importance of examining maintenance of biodiversity in fragmented landscapes that persist for hundreds of years.

A review of the introduced smooth-billed ani Crotophaga ani in Galápagos

Article

Full-text available

Nov 2018
BIOL CONSERV

The smooth-billed ani (Crotophaga ani) is a widespread introduced bird species in the biologically important archipelago of Galápagos. Many scientists and local people consider it to be a damaging invasive, and it is possible that it impacts native species and ecosystems via multiple mechanisms. However, evidence for this is largely anecdotal and research on smooth-billed anis in Galápagos is limited. Despite this, there have been repeated attempts to control or eradicate the population over the past few decades, all without long-term success. These attempts continue, but no official plan of action regarding this species currently exists. This review brings together all available information on smooth-billed anis in Galápagos. We use both published and unpublished research to answer the following questions: 1. What is known about the history of the smooth-billed anis' introduction to Galápagos? 2. What are the possible impacts of smooth-billed anis in Galápagos? 3. What attempts have been undertaken to control or eradicate smooth-billed anis in Galápagos and what were their outcomes? In answering these questions, we highlight numerous knowledge gaps, in both the current understanding of the impacts of this introduced species and the effectiveness of potential control or eradication methods. We find an urgent need for further research before considered, resource-efficient decisions can be made regarding smooth-billed anis in Galápagos.

Butterflies in Swedish grasslands benefit from forest and respond to landscape composition at different spatial scales

Article

Full-text available

Dec 2018
LANDSCAPE ECOL

Context Loss and fragmentation of semi-natural grasslands has critically affected many butterfly species in Europe. Habitat area and isolation can have strong effects on the local biodiversity but species may also be strongly affected by the surrounding matrix. Objectives We explored how different land cover types in the landscape explained the occurrence of butterfly species in semi-natural grasslands. Methods Using data from 476 semi-natural grasslands in Sweden, we analysed the effect of matrix composition on species richness and occurrence. Additionally, we analysed at which spatial scales butterflies responded to matrix types (forests, semi-natural grasslands, arable land and water). Results Forest cover showed the strongest positive effect on species richness, followed by semi-natural grasslands. Forest also had a positive effect on red-listed species at local scales. Responses to matrix composition were highly species-specific. The majority of the 30 most common species showed strong positive responses to the amount of forest cover within 200–500 m. There was a smaller group of species showing a positive response to arable land cover within 500–2000 m. Thirteen species showed positive responses to the amount of semi-natural grasslands, generally at larger scales (10–30 km). Conclusions Our study showed that surrounding forest is beneficial for many grassland butterfly species and that forests might mitigate the negative effects of habitat loss caused by agricultural intensification. Also, semi-natural grasslands were an important factor for species richness at larger spatial scales, indicating that a landscape consisting mainly of supporting habitats (i.e. forests) are insufficient to sustain a rich butterfly fauna.

Response of diurnal raptor communities to hurricane disturbance

Conference Paper

Aug 2018

The response of birds to hurricane disturbance may differ among functional groups, but little is known regarding the response of birds of prey to these disturbances. We aimed to evaluate the influence of Hurricane Patricia on the diversity of diurnal raptors in tropical dry forest in Mexico. We conducted raptor surveys at 13 sites located within the eyewall radius of maximum hurricane winds along the hurricane’s path, and 16 sites outside this area. We compared density and species richness among four habitats of deciduous and semi-deciduous forest, mangroves and agricultural fields, within the hurricane eyewall and outside the eyewall. We observed a reduction in raptor density in forests within the eyewall. Raptor density was significantly lower in deciduous forests within the eyewall compared to deciduous forests outside this area. Species richness was similar among habitats and conditions, but mangroves within the eyewall had significant higher species richness compared to mangroves outside this area. We found a significant increase in species evenness, and decrease in similarity of raptor communities in mangroves and deciduous forests within the eyewall, compared to mangroves outside the eyewall. Reduced density of raptors in forest within the path of the hurricane probably reflects the impact of winds on forest structure, whereas the increase in evenness and species richness in mangroves within the hurricane eyewall suggests that these habitats could provide refuge for raptors following hurricanes. Our results highlight the importance of maintaining landscape heterogeneity to provide alternate habitats for wildlife communities and facilitate their resilience following major disturbances.

Ecological traits modulate bird species responses to forest fragmentation in an Amazonian anthropogenic archipelago

Article

Full-text available

Jan 2018

Aim We assessed patterns of avian species loss and the role of morpho‐ecological traits in explaining species vulnerability to forest fragmentation in an anthropogenic island system. We also contrasted observed and detectability‐corrected estimates of island occupancy, which are often used to infer species vulnerability. Location Tucuruí Hydroelectric Reservoir, eastern Brazilian Amazonia. Methods We surveyed forest birds within 36 islands (3.4–2,551.5 ha) after 22 years of post‐isolation history. We applied species–area relationships to assess differential patterns of species loss among three data sets: all species, forest specialists and habitat generalists. After controlling for phylogenetic non‐independence, we used observed and detectability‐corrected estimates of island occupancy separately to build competing models as a function of species traits. The magnitude of the difference between these estimates of island occupancy was contrasted against species detectability. Results The rate of species loss as a function of island area reduction was higher for forest specialists than for habitat generalists. Accounting for the area effect, forest fragmentation did not affect the overall number of species regardless of the data set. Only the interactive model including natural abundance, habitat breadth and geographic range size was strongly supported for both estimates of island occupancy. For 30 species with detection probabilities below 30%, detectability‐corrected estimates were at least tenfold higher than those observed. Conversely, differences between estimates were negligible or non‐existent for all 31 species with detection probabilities exceeding 45.5%. Main conclusions Predicted decay of avian species richness induced by forest loss is affected by the degree of habitat specialisation of the species under consideration, and may be unrelated to forest fragmentation per se. Natural abundance was the main predictor of species island occupancy, although habitat breadth and geographic range size also played a role. We caution against using occupancy models for low‐detectability species, because overestimates of island occupancy reduce the power of species‐level predictions of vulnerability.

Flocking the City: Avian Demography and Population Dynamics in Urban Latin America

Chapter

Full-text available

Nov 2017

We here provide a general overview of the study of bird abundance, demography, and populations in urban environments with special attention on those from Latin America. We found that studies focused on bird abundance and demography were more common in Argentina, Brazil, and Mexico. We classified those species taken into account in four or more studies according to their response to urbanization. In general, specialist birds are negatively related with urbanization, whereas two invasive exotics, the Rock Pigeon (Columba livia) and House Sparrow (Passer domesticus), are present in most of the reviewed urbanized areas along Latin America. Although scarce, studies of bird demography revealed, in general, higher bird survival in urban environments, possibly due to lower predator density. However, anthropogenic causes have been identified to affect bird populations in urban areas (e.g., window and vehicle collisions, nest predation, predation by domestic cats and dogs). Future studies will importantly add to our knowledge of urban bird ecology in Latin America by continuing to quantify bird numbers and assess demography patterns, as well as identifying the factors that mold them. Birds, as highly informative and charismatic bioindicators, could play a crucial role in adding evidence-based knowledge for decision-makers to take action in building bird-friendly and livable cities.

Tracking wetland community evolution using Diptera taxonomic, functional and phylogenetic structure

Article

Nov 2017

Different processes drive spatial variation in community composition. Standard measures of composition are useful in species‐based conservation and ecology, but they may be less informative in the context of evolutionary history and functional diversity. Functional and phylogenetic approaches are increasingly used to test mechanisms driving biodiversity patterns. We studied 28 families of flies (Diptera) with a range of functional characteristics in three wetland classes (bogs, swamps, marshes) in Quebec, Canada. We examined taxonomic, phylogenetic and functional structure of communities and assessed whether rarity is deterministic or stochastic. Beta‐ and phylobeta‐diversity were also examined for relatedness to local environmental conditions, patch area, and/or surrounding landscape. Phylogenetic community structure analyses had high value and complementarity to standard measures. Environmental filtering acted on bog communities during assembly, as they emerged from a slow peat accumulation process and the plant composition is characteristic as few species can survive in these acidic and low nutrient conditions. Subsequently, community assembly happened randomly. Neutral processes of community assembly are more important in marshes and swamps, as dispersal limitation explained species abundance dynamics of small and common Diptera species. The assembly of marsh communities is a balance between neutral processes and environmental filtering, while assembly in swamps can be seen as neutral. Clustering increased with environmental extremes, indicating environmental filtering. Rare species tended to be less closely related to common species. They have unique habitat requirements, and the high diversity is maintained by temporal turnover of species with similar traits filtered by the environment.

Land use types influenced avian assemblage structure in a forest–agriculture landscape in Ghana

Article

Full-text available

Sep 2017

The conservation of biodiversity within tropical forest regions does not lie only in the maintenance of natural forest areas, but on conservation strategies directed toward agricultural land types within which they are embedded. This study investigated variations in bird assemblages of different functional groups of forest-dependent birds in three agricultural land types, relative to distance from the interior of 34 tropical forest patches of varying sizes. Point counts were used to sample birds at each study site visited. Data from counts were used to estimate species richness, species evenness, and Simpson's diversity of birds. Mean species richness, evenness, and diversity were modeled as responses and as a function of agricultural land type, distance from the forest interior and three site-scale vegetation covariates (density of large trees, fruiting trees, and patch size) using generalized linear mixed-effect models. Mean observed species richness of birds varied significantly within habitat types. Mean observed species richness was highest in forest interior sites while sites located in farm centers recorded the lowest mean species richness. Species richness of forest specialists was strongly influenced by the type of agricultural land use. Fallow lands, density of large trees, and patch size strongly positively influenced forest specialists. Insectivorous and frugivorous birds were more species-rich in fallow lands while monoculture plantations favored nectarivorous birds. Our results suggest that poor agricultural practices can lead to population declines of forest-dependent birds particularly specialist species. Conservation actions should include proper land use management that ensures heterogeneity through retention of native tree species on farms in tropical forest-agriculture landscapes.

Seuils écologiques et conservation des oiseaux forestiers dans des forêts de chênes Tunisiennes

Thesis

Full-text available

May 2016

Moez Touihri

L’objectif de la première partie de ma thèse était de déterminer les effets de la perte d’habitat, sa configuration et la composition du paysage sur certains patrons biologiques, notamment la richesse totale des oiseaux nicheurs, celle des différentes guildes et l’occurrence de cinq espèces cibles. Mes résultats ont montré que ces trois processus étaient impliqués à différents degrés. A l’échelle des communautés, la richesse spécifique totale des oiseaux nicheurs était plus fortement corrélée à la quantité de maquis haut et à la longueur de la lisière dans le paysage qu’à la réduction de la proportion de forêt. En effet, les forêts continues abritent moins d’espèces d’oiseaux nicheurs que les fragments (de 2 à 80 ha). Cependant, l’examen de la composition des assemblages d’espèces a montré une différence entre les massifs de vieilles forêts matures et les fragments. Les oiseaux cavicoles étant les espèces les plus dépendantes des grands arbres comme substrat de nidification n’étaient pas toujours absents des fragments. Certes, leur probabilité d’occurrence diminuait mais sous certaines conditions, elles pouvaient persister dans les fragments en complétant leurs besoins (ex. le Pic épeiche et le Pic de Levaillant) par des ressources trouvées dans le maquis haut ou en utilisant plusieurs fragments de forêts rapprochés pour supplémenter leurs besoins, le cas du Pic épeichette. Par contre, les espèces inféodées à une strate de végétation buissonnante profitaient de la dégradation de la forêt, par exemple par l’abattage des grands arbres, pour occuper les stations perturbées où les buissons prolifèrent. Toutefois, elles étaient totalement absentes des sites localisés à l’intérieur de la forêt, où la densité des grands arbres est très élevée et le sous-bois est absent. Le faible nombre d’espèces d’oiseaux spécialistes des forêts dans notre avifaune régionale serait aussi à l’origine de la faible richesse de l’assemblage d’oiseaux des vieilles forêts. Cet assemblage d’espèces est plus homogène et composé de plus d’espèces spécialistes que celui des fragments. A l’échelle des guildes, les nicheurs cavicoles (Fig.1) montraient une réponse positive à la quantité de forêt et à sa configuration (ex. indice de proximité) dans le paysage. Par contre, ils ont montré une réponse négative à la quantité de maquis haut. Cependant, la guilde des nicheurs en sous-bois n’a répondu significativement qu’à la perte de la forêt et à la composition du paysage. Quant à eux, les oiseaux nicheurs de la canopée n’ont montré aucune réponse significative à ces trois processus. A une échelle plus fine, celle des espèces, la réponse à la perte de forêt, sa configuration et la composition du paysage était variable. Par exemple, l’occurrence du Pic épeichette était prédite par la configuration de la forêt tandis que celles du Pic de Levaillant et du Pic épeiche répondaient plutôt à la composition du paysage. L’occurrence du Grimpereau des jardins et du Gobemouche de l’Atlas, quant à elle, était liée à la quantité de forêt à l’échelle locale et celle du paysage. La réponse positive du Pic épeiche et du Pic de Levaillant à la matrice suggère que cette dernière n’est pas complètement hostile. Nous devons donc tenir compte d’une possible complémentation à partir de la matrice chez certaines espèces (fig.2). Le maquis haut joue ainsi un rôle qui ne devrait pas être négligé dans le développement des cibles de la conservation. Toutefois, la réponse négative du Pic épeichette, du Grimpereau des jardins et du Gobemouche de l’Atlas envers le maquis haut ne devrait pas être sous-estimée non plus (fig.2). Par rapport au maquis haut, le maquis bas a un effet négatif sur l’occurrence de toutes les espèces cavicoles. Seules quelques espèces de fauvettes comme la Fauvette pitchou, à lunette, passerinette et grisette ont montré une affinité pour la végétation buissonnante basse et dense. Ces deux types de maquis partagent plusieurs espèces végétales. La différence est principalement due à la hauteur de la végétation et la présence de certains pieds d’arbres isolés dans le maquis haut. L’amélioration du maquis bas par la plantation des arbres et la réduction du pâturage qui exerce une pression continue sur ce milieu atténuerait le contraste du paysage. La présence d’effets de lisière et de la proximité de la forêt (fragmentation au sens strict) d’intensité variable selon les guildes devrait être prise en considération. Par exemple, dans le cas du Pic épeichette, la seule espèce qui a répondu significativement à l’indice de proximité, planter de petites parcelles de forêt dans le maquis (marche-pieds), même si les densités des arbres ne soient pas élevées, devrait améliorer la connectivité structurale et aider cette espèce à persister dans les fragments d’habitat isolés. Le deuxième volet de ma thèse avait pour objectif de contribuer au développement d’outils nécessaires à la conservation des forêts de chênes du nord-ouest tunisien en se focalisant sur la réponse des espèces les plus sensibles à la dégradation de l’habitat forestier à l’échelle locale. Par dégradation, je référais à la collecte de bois mort, à l’abattage des grands arbres et au pâturage par le bétail. Je me suis basé sur la notion des seuils écologiques pour quantifier les besoins des espèces d’oiseaux les plus exigeants termes d’habitat forestiers. Les valeurs obtenues m’ont permis de proposer aux gestionnaires des valeurs pratiques qui pourraient être utilisées comme référence pour l’identification et la gestion des parcelles forestières. Ainsi, les seuils de 650 tiges ha-1 d'arbres (dhp >30 cm), 207 tiges ha-1 de chicots (fig.3), 213 tiges ha-1 de bois mort par terre et une canopée maintenue à 75 % devrait être respectés lors de l’application d’un éventuel traitement sylvicole. Ces chiffres correspondaient aux seuils les plus élevés des différentes espèces cibles notamment (le Pic épeiche, Pic de Levaillant, Pic épeichette, le Gobe mouche de l’Atlas et Grimpereau des jardins) assurant une détectabilité de 0,9. Les parcelles forestières ayant des valeurs plus élevées que ces dernières pourraient être exploitées tout en respectant les besoins des espèces les plus sensibles. Les seuils de nidification peuvent être plus élevés que ceux liés à la simple occurrence des espèces. Je me suis donc intéressé aux choix de la réponse biologique pour exprimer les seuils. Est-il plus prudent de se fier aux besoins de nidification plutôt qu’à ceux liés à la simple occurrence ? Cette question a été abordée à travers la modélisation de l’habitat de nidification de deux espèces de pic notamment le Pic épeiche et le Pic de Levaillant. Bien que ces deux espèces, préfèrent le bois mort et les grands arbres dhp > 40 cm comme substrat de nidification (fig.5), j’ai trouvé une différence concernant la quantité de ces éléments. Le Pic épeiche est plus exigent que le Pic de Levaillant dans la sélection de la zone de nidification. En effet, les sites de nidification ont une densité plus importante de grands arbres que les sites où l’espèce a été simplement détectée. Par conte aucune différence entre les deux types de sites n’a été trouvée chez le Pic de Levaillant. Ce résultat complique la tâche des gestionnaires dans la mesure où on ne peut pas vraiment trancher. D’une part, les seuils de nidification ne sont pas toujours plus élevés que ceux liés à l’occurrence (cas du Pic de Levaillant) et d’autre part, on doit en tenir compte puis qu’une différence a été trouvée. Cette tâche pourrait être plus complexe si on s’intéresse à d’autres paramètres biologiques comme le succès reproducteur. En tenant compte de l’effort déployé pour la mesure des différents paramètres biologiques et du choix de l’espèce cible, je pense que se fier aux besoins de nidification des espèces cibles serait plus sécuritaire pour la conservation des écosystèmes forestiers. J’encourage aussi l’utilisation de plusieurs espèces sensibles plutôt qu’une seule espèce afin de minimiser le risque de sous-estimer les besoins des espèces les plus sensibles.

Forest disturbance has negative consequences for the persistence of Jamaica’s threatened and endangered bird species in Cockpit Country

Article

Dec 2017

Herlitz Davis

Cockpit Country is a globally important area for Jamaica’s threatened and endangered bird species. But habitat disturbance and degradation due to lumber and yam stick extraction, small-scale agriculture, and bauxite mining threaten to disrupt the sensitive ecological processes that maintain both the species and the habitat. Analysis of anthropogenic forest disturbance and point count survey data for birds suggests an association between forest disturbance and bird distribution patterns in Cockpit Country. Threatened and endangered birds such as Plain Pigeon (Patagioenas inornata exigua), Crested Quail- Dove (Geotrygon versicolor), and Jamaican Blackbird (Nesopsar nigerrimus) had greater association with undisturbed forest than species of least conservation concern such as Common Ground-Dove (Columbina passerina) and Gray Kingbird (Tyrannus dominicensis). Although the observed distribution patterns revealed a suite of bird species that could be utilized for monitoring forest disturbance, the approach used in this study needs to be better developed before implementation in Cockpit Country. The results also have implications for the persistence of threatened and endangered bird species given the lack of clarity about boundaries, proper forest management and enforcement, and ongoing efforts to mine bauxite in the area. Keywords: birds, Cockpit Country, endangered, forest disturbance, threatened Resumen: El disturbio forestal tiene consecuencias negativas para la subsistencia de las aves amenazadas y en peligro de Jamaica en Cockpit Country—Cockpit Country es un área de importancia mundial para las especies de aves amenazadas y en peligro de Jamaica. Sin embargo, la degradación y el disturbio de hábitat producto de la tala y la extracción de ñame, la agricultura a pequeña escala y la explotación de bauxita amenazan con interrumpir los sensibles procesos ecológicos que mantienen tanto a las especies como al hábitat. El análisis de los disturbios forestales por causas antropogénicas y los datos de muestreos de puntos de conteo de aves sugiere una asociación entre el disturbio forestal y los patrones de distribución de aves en Cockpit Country. Especies amenazadas y en peligro como Patagioenas inornata exigua, Geotrygon versicolor y Nesopsar nigerrimus tuvieron una mayor asociación con bosques no perturbados que especies de menor preocupación como Columbina passerina y Tyrannus dominicensis. Aunque los patrones de distribución observados revelan que podría utilizarse un grupo de aves para el monitoreo del disturbio forestal, el enfoque empleado en este estudio necesita ser desarrollado mejor antes de su implementación en Cockpit Country. Los resultados también tienen implicaciones para la subsistencia de especies de aves amenazadas y en peligro dada la falta de claridad sobre los límites, la aplicación de la ley la presencia de un manejo forestal adecuado, así como los esfuerzos en curso para la extracción de bauxita en el área. Palabras clave: amenazadas, aves, Cockpit Country, disturbio forestal, en peligro Résumé: Conséquences négatives des perturbations des forêts pour le maintien des espèces d’oiseaux menacées et en danger à Cockpit Country en Jamaïque—Cockpit Country est une aire d’importance mondiale pour les espèces d’oiseaux menacées et en danger de la Jamaïque. Toutefois, la perturbation et la dégradation des habitats en raison de l’exploitation du bois et de l’igname, l’agriculture à petite échelle et les mines de bauxite menacent de modifier les processus écologiques sensibles qui maintiennent les espèces et les habitats. L’analyse des perturbations d’origine anthropique de la forêt et des comptages des oiseaux par points suggère l’existence d’un lien entre la perturbation de la forêt et les modèles de répartition des oiseaux à Cockpit Country. Les oiseaux menacés et en danger comme le Pigeon simple (Patagioenas inornata exigua), la Colombe versicolore (Geotrygon versicolor), et le Carouge de la Jamaïque (Nesopsar nigerrimus) sont plus fortement associés à la forêt non perturbée que les espèces dont la conservation est moins préoccupante telles que la Colombe à queue noire (Columbina passerina) et le Tyran gris (Tyrannus dominicensis). Bien que les schémas de répartition observés aient mis en évidence une série d’espèces d’oiseaux qui permettrait de suivre les perturbations forestières, l’approche utilisée dans cette étude doit être développée davantage avant une mise en oeuvre à Cockpit Country. Les résultats ont également des implications pour le maintien des espèces d’oiseaux menacées et en danger, compte tenu du manque de clarté quant aux limites, à la bonne gestion des forêts, et à l’application des lois, ainsi qu’aux efforts actuels d’extraction de la bauxite dans la région. Mots clés: Cockpit Country, espèces en danger, espèces menacées, oiseaux, perturbation des forêts

Climate-driven variation in dispersal ability predicts responses to forest fragmentation in birds

Article

Full-text available

May 2023
Nat. Ecol. Evol.

Species sensitivity to forest fragmentation varies latitudinally, peaking in the tropics. A prominent explanation for this pattern is that historical landscape disturbance at higher latitudes has removed fragmentation-sensitive species or promoted the evolution of more resilient survivors. However, it is unclear whether this so-called extinction filter is the dominant driver of geographic variation in fragmentation sensitivity, particularly because climatic factors may also cause latitudinal gradients in dispersal ability, a key trait mediating sensitivity to habitat fragmentation. Here we combine field survey data with a morphological proxy for avian dispersal ability (hand-wing index) to assess responses to forest fragmentation in 1,034 bird species worldwide. We find that fragmentation sensitivity is strongly predicted by dispersal limitation and that other factors—latitude, body mass and historical disturbance events—have relatively limited explanatory power after accounting for species differences in dispersal. We also show that variation in dispersal ability is only weakly predicted by historical disturbance and more strongly associated with intra-annual temperature fluctuations (seasonality). Our results suggest that climatic factors play a dominant role in driving global variation in the impacts of forest fragmentation, emphasizing the need for more nuanced environmental policies that take into account local context and associated species traits.

The effect of flight efficiency on gap‐crossing ability in Amazonian forest birds

Article

May 2022

The ability to move across the landscape is a fundamental property of species that can determine their chances of persistence in fragmented landscapes and in rapidly changing environments. Despite its importance, empirical evidence showing the effect of movement capacity on patterns of movement across fragmented landscapes is limited. In this study, we examine the role of flight efficiency on the likelihood of crossing a man‐made habitat gap. We used data from the Biological Dynamics of Forest Fragments Projects on recaptures of banded birds in an Amazonian forest bisected by a road. For a total of 45 species, we estimated flight efficiency using the hand‐wing index (a proxy for the wing's aspect ratio) and used it as a predictor of the probability of road crossing in phylogenetic binomial regression models. We found that flight efficiency was a strong predictor of road‐crossing probability: species with high hand‐wing indices crossed the road more frequently than those with low hand‐wing indices. In contrast, other characteristics such as body mass, diet, flocking behavior, and foraging stratum did not show significant associations with road‐crossing probability. Our results suggest that proxies of flight efficiency such as the hand‐wing index can be powerful tools for predicting the vulnerability of bird species to forest fragmentation. Abstract in Spanish is available with online material

Trait‐habitat associations explain novel bird assemblages mixing native and alien species across New Zealand landscapes

Article

Full-text available

Nov 2021
DIVERS DISTRIB

Aim Species introductions have reshaped island faunas for the last 200 years, often threatening native biodiversity. Approximately equal numbers of native and alien species currently co‐occur in the New Zealand avifauna, but they show distinct habitat use. Antagonistic interactions, habitat affinities and legacies of introduction history may concur to explain their segregation along habitat gradients. To investigate these processes, we explored how habitat, ecological traits and introduction history relate with the current composition of bird assemblages. Location New Zealand Taxon Birds Methods We analysed 917 bird point counts spread along habitat and elevation gradients in the Canterbury region, South Island and related 10 ecological traits to landscape composition using a three‐table ordination method known as “RLQ analysis”, accounting for spatial autocorrelation and phylogeny. We tested whether alien species’ positions in the RLQ were related to proxies of introduction history. Results Eighteen endemic, 11 native and 19 alien species were distributed along a gradient from forest to open‐habitat assemblages, in relation to foraging mode, nesting site and body size. A second gradient segregated species between native and exotic forests according to territoriality, sedentarity and diet. Traits accounted for the separation of native and alien bird species in forests, but not in open habitats. Phylogenetic signals emerged from the separation of native and alien species by forest type, and spatial structures suggested a landscape‐level, rather than regional or local determinism. These correlations were independent of introduction history, although open‐habitat assemblages tended to host alien species introduced later in time. Main conclusions Habitat type and resource availability explain the spatial partitioning of New Zealand bird assemblages between native and alien species more consistently than competitive exclusion. We conclude that trait‐mediated ecological differences among species have likely played a predominant role in species’ segregation among landscapes, while maintaining endemic bird assemblages in native forests.

Impact of Vegetation Cover Structure on Birds' Community at Tianfu National Wetland Park in Jiangsu Kunshan, China

Preprint

Full-text available

Sep 2021

Vegetation cover has an essential role in wetland habitats in controlling avian populations throughout the world. The vegetation cover structure in grassland systems varies dramatically among seasons on the same sites. Variation in vegetation cover-abundance richness and diversity has been studied through one hundred forty-seven quadrate samples during summer and autumn, 2019, winter, and spring 2020. Avian spe cies richness and diversity were recorded during the same period. Meanwhile, correlation analysis results confirmed that: (1) there was no apparent seasonal difference in the abundance of vegetation cover while avian abundance was statistically different. (2) Plant abundance in summer was positively correlated with the number of avian, while in autumn it was negatively correlated. Plant and avian abundance at the genus level showed a positive correlation while maintaining a negative correlation at the speci es level (p < 0.05). However, during summer and autumn, a strong linear relationship exists between vegetation coverage and avian. The Shannon diversity index and Simpson diversity index have a positive linear relationship between vegetation coverage and a vian families and genera. Therefore, we conclude that vegetation coverage and richness significantly impact avian communities. We suggest further research into the relationship between other biological communities and farming practices in the wetlands.

Effects of forest fragmentation on bird communities in NW Ethiopia

Preprint

Full-text available

Dec 2014

Anthropogenic disturbance regimes in areas that were once large continuous habitats have been major drivers of habitat fragmentation and loss which in turn form the largest worldwide threat to avian biodiversity. Studies suggest that functional trait based approaches provide better understanding of fragmentation effects on ecological processes in human-modified landscapes. However, research on these thematic areas is limited in many tropical regions, such as Ethiopia. In this study, we evaluated sensitivity of bird communities and functional groups to fragmentation processes in Ethiopia. Standard point counts were used to survey birds in 16 remnant forest patches of variable sizes and degrees of isolation. The information theoretic model selection approach was used for precise understanding of avian functional group responses to habitat loss and fragmentation. Results showed strong impacts of forest loss and fragmentation on forest specialists, insectivores, frugivores, open nesters, understorey nesters and resident birds. Protection and restoration of the remnant forest patches may help mitigate the negative effects of fragmentation on such specialist bird functional groups.

Forest disturbance has negative consequences for the persistence of Jamaica's threatened and endangered bird species in Cockpit Country A Special Issue on the Status of Caribbean Forest Endemics

Preprint

Full-text available

Dec 2017

Herlitz Davis

Análisis comparativo de las aves entre dos zonas boscosas de Pueblo Viejo, Chiapas, México

Article

Full-text available

Sep 2018

La falta de información básica sobre poblaciones de aves, ha limitado realizar propuestas de conservación local. Por lo anterior, el objetivo fue comparar la avifauna de dos localidades, ubicadas entre los municipios de las Las Rosas y Comitán de Domínguez, en Chiapas, México. El registro de individuos se realizó en 80 puntos de conteo, a las especies registradas se les asignó estatus de temporalidad de residencia y riesgo, de sensibilidad a disturbios provocados por actividades humanas y gremio trófico, además se realizaron análisis de abundancia relativa y de números de Hill, para reconocer especies raras. También se estimó la diversidad beta y complementariedad de especies, entre localidades. Se registraron 113 especies, 86 residentes, 22 migratorias invernales, una migratoria de verano y cuatro transitorias. La más alta riqueza y abundancia de especies se registró en Candelaria en la temporada de secas, siendo la mayoría rara. Candelaria tiene 15 especies en riesgo, 55 tienen baja sensibilidad a disturbios, 44 media y dos alta. En Guadalupe Palmira el registro de especies fue menor en todas las categorías. Las especies fueron principalmente insectívoras (56 especies) y omnívoras arbóreas (19 especies), la diversidad beta fue del 39% y la complementariedad del 56%.

Who Is Who in the City? Bird Species Richness and Composition in Urban Latin America

Chapter

Nov 2017

Urban ecology in Latin America still lags behind temperate developed countries; yet, knowledge in the region has increased remarkably in the last decade. Based on previously published literature, including major global and regional reviews, we underline the prominent patterns of bird species richness and composition recorded in urban Latin America, summarizing the main factors influencing such patterns and contrasting them with those found in other regions of the world. To obtain an updated set of publications focused on bird species richness and composition in Latin America, we performed a search in the Web of Science for literature published up to 2015. After filtering out publications not considering bird species richness and/or composition, a total of 464 remained. We classified the assessed publications in relation to the study area (region and country), publication year, general aims, and main findings. We found notable similarities and differences between patterns described in studies from across the globe and from those described in previous literature reviews focused on Latin American studies. Some of the most recent publications support previously identified patterns, providing a more comprehensive understanding of how birds are responding to urbanization and its associated processes. Finally, we highlight some areas of research opportunity that could broaden our comprehension of bird ecology in relation to urbanization in Latin America. In sum, we recommend further studies assessing bird species richness and composition in urban Latin America to consider more comprehensive and comparative approaches that account for the variability of conditions occurring within urban areas, including highly developed and depauperated sites at different geographical and temporal scales.

Trait-based indicators of bird species sensitivity to habitat loss are effective within but not across datasets

Article

Oct 2017

Species’ traits have been widely championed as the key to predicting which species are most threatened by habitat loss, yet previous work has failed to detect trends that are consistent enough to guide large-scale conservation and management. Here we explore whether traits and environmental variables predict species sensitivity to habitat loss across two datasets generated by independent avifaunal studies in the Atlantic Forest of Brazil, both of which detected a similar assemblage of species, and similar species-specific responses to habitat change, across an overlapping sample of sites. Specifically, we tested whether 25 distributional, climatic, ecological, behavioral and morphological variables predict sensitivity to habitat loss among 196 bird species, both within and across studies, and when data were analysed as occurrence or abundance. We found that 4-9 variables showed high explanatory power within a single study or dataset, but none performed as strong predictors across all datasets. Our results demonstrate that the use of species traits to predict sensitivity to anthropogenic habitat loss can produce predictions that are species- and site-specific and not scalable to whole regions or biomes, and thus should be used with caution. This article is protected by copyright. All rights reserved.

A Removal Model for Estimating Detection Probabilities From Point-Count Surveys

Article

Full-text available

Apr 2002

Use of point-count surveys is a popular method for collecting data on abundance and distribution of birds. However, analyses of such data often ignore potential differences in detection probability. We adapted a removal model to directly estimate detection probability during point-count surveys. The model assumes that singing frequency is a major factor influencing probability of detection when birds are surveyed using point counts. This may be appropriate for surveys in which most detections are by sound. The model requires counts to be divided into several time intervals. Point counts are often conducted for 10 min, where the number of birds recorded is divided into those first observed in the first 3 min, the subsequent 2 min, and the last 5 min. We developed a maximum-likelihood estimator for the detectability of birds recorded during counts divided into those intervals. This technique can easily be adapted to point counts divided into intervals of any length. We applied this method to unlimited-radius counts conducted in Great Smoky Mountains National Park. We used model selection criteria to identify whether detection probabilities varied among species, throughout the morning, throughout the season, and among different observers. We found differences in detection probability among species. Species that sing frequently such as Winter Wren (Troglodytes troglodytes) and Acadian Flycatcher (Empidonax virescens) had high detection probabilities (∼90%) and species that call infrequently such as Pileated Woodpecker (Dryocopus pileatus) had low detection probability (36%). We also found detection probabilities varied with the time of day for some species (e.g. thrushes) and between observers for other species. We used the same approach to estimate detection probability and density for a subset of the observations with limited-radius point counts.

Classification and regression trees: A powerful yet simple technique for ecological data analysis

Article

Full-text available

Jan 2002

Effects of forest fragmentation by agriculture on avian communities in the southern boreal mixedwoods of western Canada

Article

Full-text available

Sep 2000
Wilson Bull

Little is known about the effects of forest fragmentation on bird communities in the boreal forests of western North America. Assessing the impact of forest fragmentation on bird communities has been complicated by the fact that few studies have applied statistical analyses that account for the possibility that individuals are randomly dispersed within landscapes. From 1993-1997, we contrasted bird communities in contiguous forest (54 sites) and nearby forest fragments surrounded by agricultural land (106 sites, 0.2-123 ha). Species were divided into groups based on migratory strategy (resident, short-distance migrant, long-distance migrant, and irruptive) and edge-sensitivity (edge, edge-interior, and interior). For each group, we tested whether richness and abundance were different from what would be expected if birds were distributed randomly across landscapes. Species richness was higher than expected in contiguous forest for interior species, whereas edge and short-distance migratory species were more common in the fragmented landscape. Similarly, the total abundance of interior and long-distance migratory birds was higher in contiguous forest, whereas edge birds were more abundant in the fragmented landscape. Brown Creeper (Certhia americana), Swainson's Thrush (Catharus ustulatus), Tennessee Warbler (Vermivora peregrina), Magnolia Warbler (Dendroica magnolia), Blackburnian Warbler (Dendroica fusca), Black-throated Green Warbler (Dendroica virens), and Bay-breasted Warbler (Dendroica castanea) were virtually absent from the fragmented landscape, yet were common in contiguous forest. Within the fragmented landscape, forest fragment size had little effect on species richness but was significantly correlated with abundance of all migratory and edge-sensitivity groups except edge and short-distance migrants. Probability of occurrence, controlling for random placement, was positively correlated with forest fragment size, percent forest cover within 5 km, or the interaction between size and cover for 19 species, most of which were associated with forest interiors. Predation and brood parasitism were higher on nests of ground and shrub nesting birds in the fragmented landscape than in contiguous forest. Fragmentation of contiguous forest in the southern boreal mixedwood zone of western Canada has a negative impact on the abundance of several resident and long-distance migratory species.

Effect of natural and anthropogenic landscape matrices on the abundance of subandean bird species

Article

Full-text available

Feb 2001

Luis Miguel Renjifo

The nature of the landscape matrix can control the capacity of forest organisms to move among forest patches. Some matrices may constitute foraging or breeding habitat and, as a result, could influence the local abundance of forest organisms and their persistence in fragmented landscapes. This study represents a first approach to examining the effect of natural vs. anthropogenic landscape matrices on the abundance of neotropical birds in forest sites. The influence of three contrasting matrices on the relative abundance of 113 bird species in a subandean region was evaluated. Species were grouped into categories showing the same response to the matrix, and these groups were then examined to determine whether ecological characteristics or taxonomic affinities were associated with responses to surrounding matrices. The abundance of individual species in forest plots within a continuous forest matrix was compared with their abundance in forest fragments embedded in pastures or exotic-tree plantations. The matrix surrounding forest areas was a major factor influencing bird abundance: 65.5% of the species showed significant differences in abundance among sites surrounded by different matrices. The most important explanatory factors in the variation in abundance within fragments were: abundance within continuous forest, presence in the anthropogenic matrices, migratory strategy, and habitat association. Species with small geographic ranges and species of terrestrial insectivores had low tolerance to fragmentation. Responses were highly species specific and largely independent of foraging strata, trophic group, and taxonomic affinities. Several lines of evidence indicate an increased connectivity among forest remnants surrounded by exotic-tree plantations compared to pastures. Landscape supplementation by the exotic-tree plantation matrix was observed for a hummingbird species. These results suggest that structurally complex anthropogenic matrices have potential as management tools for bird conservation by complementing habitat protection and restoration.

A Fixed-radius Point Count Method for Nonbreeding and Breeding Season Use

Article

Full-text available

Jul 1986
AUK

We provide a detailed description of a fixed-radius point count method that carries fewer assumptions than most of the currently popular methods of estimating bird density and that can be used during both the nonbreeding and breeding seasons. The method results in three indices of bird abundance, any of which can be used to test for differences in community composition among sites, or for differences in the abundance of a given bird species among sites. These indices are (1) the mean number of detections within 25 m of the observer, (2) the frequency of detections within 25 m of the observer, and (3) the frequency of detections regardless of distance from the observer. The overall ranking of species abundances from a site is similar among the three indices, but discrepancies occur with either rare species that are highly detectable at great distances or common species that are repulsed by, or inconspicuous when near, the observer. We argue that differences in the behavior among species will preclude an accurate ranking of species by abundance through use of this or any other counting method in current use.

Cumulative Effects of Barriers on the Movements of Forest Birds

Article

Full-text available

Jan 2001
ECOL SOC

"Although there is a consensus of opinion that habitat fragmentation has deleterious effects on animal populations, primarily by inhibiting dispersal among remaining patches, there have been few explicit demonstrations of the ways by which degraded habitats actually constrain individual movement. Two impediments are primarily responsible for this paucity: it is difficult to separate the effects of habitat fragmentation (configuration) from habitat loss (composition), and conventional measures of fragmented habitats are assumed to be, but probably are not, isotropic. We addressed these limitations by standardizing differences in forest cover in a clearly anisotropic configuration of habitat fragmentation by conducting a homing experiment with three species of forest birds in the Bow Valley of Banff National Park, Canada. Birds were translocated (1.2-3.5 km) either parallel or perpendicular to four/five parallel barriers that are assumed to impede the cross-valley travel of forest-dependent animals. Taken together, individuals exhibited longer return times when they were translocated across these barriers, but differences among species suggest a more complex interpretation. A long-distance migrant (Yellow-rumped Warbler, Dendroica coronata) behaved as predicted, but a short-distance migrant (Golden-crowned Kinglet, Regulus satrapa) was indifferent to barrier configuration. A resident (Red-breasted Nuthatch, Sitta canadensis) exhibited longer return times when it was translocated parallel to the barriers. Our results suggest that an anisotropic arrangement of small, open areas in fragmented landscapes can have a cumulative barrier effect on the movement of forest animals, but that both modelers and managers will have to acknowledge potentially counterintuitive differences among species to predict the effect that these may have on individual movement and, ultimately, dispersal."

Classification and Regression Trees: A Powerful Yet Simple Technique for Ecological Data Analysis

Article

Full-text available

Nov 2000

Classification and regression trees are ideally suited for the analysis of complex ecological data. For such data, we require flexible and robust analytical methods, which can deal with nonlinear relationships, high-order interactions, and missing values. Despite such difficulties, the methods should be simple to understand and give easily interpretable results. Trees explain variation of a single response variable by repeatedly splitting the data into more homogeneous groups, using combinations of explanatory variables that may be categorical and/or numeric. Each group is characterized by a typical value of the response variable, the number of observations in the group, and the values of the explanatory variables that define it. The tree is represented graphically, and this aids exploration and understanding. Trees can be used for interactive exploration and for description and prediction of patterns and processes. Advantages of trees include: (1) the flexibility to handle a broad range of response types, including numeric, categorical, ratings, and survival data; (2) invariance to monotonic transformations of the explanatory variables; (3) ease and robustness of construction; (4) case of interpretation; and (5) the ability to handle missing values in both response and explanatory variables. Thus, trees complement or represent an alternative to many traditional statistical techniques, including multiple regression, analysis of variance, logistic regression, log-linear models, linear discriminant analysis, and survival models. We use classification and regression trees to analyze survey data from the Australian central Great Barrier Reef, comprising abundances of soft coral taxa (Cnidaria: Octocorallia) and physical and spatial environmental information. Regression tree analyses showed that dense aggregations, typically formed by three taxa, were restricted to distinct habitat types, each of which was defined by combinations of 3-4 environmental variables. The habitat definitions were consistent with known experimental findings on the nutrition of these taxa. When used separately, physical and spatial variables were similarly strong predictors of abundances and lost little in comparison with their joint use. The spatial variables are thus effective surrogates for the physical variables in this extensive reef complex, where information on the physical environment is often not available. Finally, we compare the use of regression trees and linear models for the analysis of these data and show how linear models fail to find patterns uncovered by the trees.

Tropical countryside bird assemblages: Richness, composition, and foraging differ by landscape context

Article

Full-text available

Feb 2003

In tropical regions worldwide, large tracts of native rain forest have been replaced by agricultural systems. Appropriate management of these systems may contribute to biodiversity conservation, but we have limited knowledge of the effect of different management strategies on species persistence. We examined the capacity of tropical country ide in southern Costa Rica to provide resources for avian frugivores. Bird assemblages visiting fruiting Miconia trees were recorded in five landscape contexts: sites near (<2 km from) a large (227-ha) rain forest remnant, split between high and low agricultural intensity; sites far (5-8 km) from the remnant, similarly split; and the remnant itself.. Across all landscape contexts, 73 native bird species were observed taking fruit from Miconia. The composition of frugivore assemblages differed significantly among agricultural landscape contexts. Species richness was highest in near, low-intensity sites (21.5 +/- 1.79, mean +/- 1 SE) and lowest in far, high-intensity sites (14.1 +/- 0.89). The visitation rates of frugivores did not differ among landscape contexts for all species combined, but there were significant differences in the frequency of visits for 10 individual species. Large, socially dominant frugivores were common visitors to trees in far, high-intensity agricultural sites, whereas the visitation rates of many smaller, subordinate frugivores (e.g., small tanagers) declined with distance from the large rain forest remnant or in high-intensity sites. Also, some forest-dependent species (e.g., White-ruffed Manakin, Corapipo altera) were infrequently recorded at fruiting trees in high-intensity and far sites. However, trees in far sites provided resources to species that use both forest and agricultural habitats. Isolated fruiting trees in our study area appear to be an important resource for many avian frugivores. Use of these trees by a wide range of species is enhanced by their proximity to relatively large areas of native rain forest. Low-intensity agriculture that incorporates fruiting trees as part of live fences, windbreaks, or shade and allows for the preservation of rain forest remnants, would be beneficial to biodiversity conservation in the tropics and may facilitate the regeneration of bird-dispersed rain forest plants.

Effect of Natural and Anthropogenic Landscape Matrices on the Abundance of Subandean Bird Species

Article

Full-text available

Feb 2001

Luis Miguel Renjifo

Forest cover and deforestation in Jamaica: An analysis of forest cover estimates over time

Article

Full-text available

Dec 2003

Forest cover and related deforestation data published in reputable international forest assessment documents during the past decade have characterised the island of Jamaica as having one of the world's highest rates of deforestation. An analysis of pre-1990 land use data together with a detailed study of 1989 and 1998 LANDSAT TM imagery of the island revealed that there were fundamental errors in the data used during the 1990s. A study by the Forestry Department and the Trees for Tomorrow Project found that the annual rate of deforestation for the period 1989-1998 was 0.1%, much less than had been previously estimated. This paper seeks to explain the variation in existing forest cover data, its change over time and to point to the need for more accurate and reliable data to be developed internally, based on a rigorous forest cover definition, forest type classification and monitoring methodology.

Effects of Residential Development on Forest-Dwelling Neotropical Migrant Songbirds

Article

Full-text available

Dec 1995
CONSERV BIOL

Many bird species are in local or regional decline because of habitat loss or degradation. We attempted to disentangle the effects of residential development from the effects of forest size on forest-bird communities, with particular emphasis on Neotropical migrant species. Two variables were examined for their influence on avian diversity and abundance: forest size and the number of houses outside a forest within 100 m of the edge. We found that Neotropical migrants consistently increased in number and abundance as forest size increased. Of greater interest, we found that the number of houses surrounding a forest severely undermined its suitability for Neotropical migrants. Neotropical migrants consistently decreased in diversity and abundance as the level of adjacent development increased, regardless of forest size. The effects of development were striking: 4-ha woodlots without any nearby houses had on average a richer, more abundant Neotropical community than did 25-ha urban woodlots. No predictable pattern of change concerning development or forest size was observed for short-distance migrants or permanent residents. Current planning regulations generally permit housing right up to forest edges. This practice may prevent protection of ecological features within the forest. Threshold distances for housing developments around forests need to be determined to prevent or minimize adverse effects on features and functions within the forests.

The Effects of Edge Permeability and Habitat Geometry on Emigration from Patches of Habitat

Article

Full-text available

Apr 1987

Edge permeability, phi, reflects the tendency of a disperser reaching the edge of a habitat patch to cross the boundary and emigrate; edge permeability is positively related to emigration for any given habitat patch. The edge-to-size ratio (ESR), its the proportion of home ranges at the edge of a habitat patch; for any degree of edge permeability greater than zero, the ESR is positively related to emigration. When habitats have relatively hard edges (e.g., 0 = or < phi = or < 0.1), edge permeability is a more important determinant of emigration than is the ESR. When habitats have relatively soft edges (phi > 0.1), the ESR is the more important determinant. -from Authors

Habitat Loss and Population Decline: A Meta-Analysis of the Patch Size Effect

Article

Full-text available

Mar 1998

We evaluated the conditions under which patch size effects are important determinants of local population density for animals living in patchy landscapes. This information was used to predict when patch size effects will be expected to occur following habitat loss and fragmentation. Using meta-analysis, we quantitatively reviewed the results of 25 published studies that tested for a relationship between patch size and population density. Patch size effects were strong for edge and interior species (negative and positive patch size effects, respectively), but negligible for generalist species that use both edge and interior habitat. We found significant differences in mean patch size effects between migratory and residential species, between herbivores and carnivores, and among taxonomic groups. We found no evidence that patch size effects were related to landscape characteristics such as the proportion of landscape covered by habitat, median patch size, or the scale at which a study was conducted. However, species in the Western Hemisphere tended to have larger absolute effect sizes, and eastern species tended to be more variable in their response. For landscapes undergoing habitat loss and fragmentation, our results predict the following: (1) among generalist species that use both the edge and the interior of a habitat patch, the decline in population size associated with habitat destruction should be accounted for by pure habitat loss alone; (2) for interior species, the decline in population size associated with habitat fragmentation per se will be greater than that predicted from pure habitat loss alone; (3) for edge species, the decline in population size will be less than that predicted by pure habitat loss alone; (4) these relative effects will not be influenced by the extent of habitat loss, but they will be affected by the pattern of habitat when large or small patches are preferentially removed; and (5) as loss and fragmentation increase within a landscape, migratory species will generally suffer less of a decline in population size than resident species.

Corvid Density and Nest Predation in Relation to Forest Fragmentation: A Landscape Perspective

Article

Full-text available

Jun 1992

Henrik Andrén

The abundance and distribution of corvids (Common Raven, Corvus corax; Hooded Crow, C. corone; Jackdaw, C. monedula; Black-billed Magpie, Pica pica; and European Jay, Garrulus glandarius) were studied across a gradient from a landscape dominated by agricultural land to a landscape dominated by forest in south-central Sweden. The total density and the predation rate on dummy nests increased as the proportion of agricultural land increased. This supports the suggestion that the density of corvids increases as forest becomes fragmented and intermixed with agricultural land, causing an increase in nest predation in small forest fragments. However, the different species responded differently to the proportion of forest in the landscape. The two forest-living corvids, the Jay and Raven, were absent from small forest fragments in a matrix of agricultural land and mainly preyed upon dummy nests inside the large forest fragments. Thus, both of these species were habitat specialists restricted to forests. Three corvids basically inhabit agricultural land, the Hooded Crow, Jackdaw, and Magpie. The Jackdaw and the Magpie showed a strong preference for agricultural land and they mainly preyed upon dummy nests in agricultural land. On the other hand, the density of Hooded Crows was higher in landscapes with a mixture of agricultural land and forest than in landscapes dominated by either agricultural land or forest, indicating a use of both agricultural land and forest. Further, Hooded Crows regularly preyed upon nests in both forest habitat and agricultural land; it is a habitat generalist. Therefore, the Hooded Crow was the most important species in the corvid family, causing increased predation pressure close to forest-farmland edges and in small forest fragments surrounded by agricultural land.

Forty-Seventh Supplement to the American Ornithologists' Union Check-List of North American Birds

Article

Jul 2006

Resampling-Based Multiple Testing: Examples and Methods for p-Value Adjustment.

Article

Dec 1994

The Analysis of Contingency Tables

Article

May 1993

How Habitat Edges Change Species Interactions

Article

Feb 1999

Traditionally, ecologists interested in habitat edges have focused on edge‐related gradients in patterns of species richness or abiotic variables. Here, however, we take a different perspective, attempting to synthesize recent empirical results concerning the effects of habitat edges on population dynamics with contemporary theoretical developments to outline the ways in which species interactions, and the dynamics of the communities in which they are embedded, can be changed by habitat edges. We find a striking convergence between empirical notions of a patch's core area and analytical results from partial differential equation models. A review of both empirical and theoretical studies suggests four general classes of mechanisms through which habitat edges can have similar impacts on dissimilar types of species interactions. Specifically, we focus on edges' roles as dispersal barriers or filters, edges' influences on mortality, edges' involvement in spatial subsidies (in which dispersers' intrapatch impacts are maintained by their activities in other habitats), and edges' roles as generators of novel interactions. For each class of edge‐mediated effects, we provide examples of how one can use spatial modeling to address the relevant questions on these topics, which together form a key link between community dynamics and landscape structure.

Conservation and controversy: National forest management, 1960-95

Article

Jan 1997

L. Ruth

The Theory of Island Biogeography

Article

Jan 1967

This book had its origin when, about five years ago, an ecologist (MacArthur) and a taxonomist and zoogeographer (Wilson) began a dialogue about common interests in biogeography. The ideas and the language of the two specialties seemed initially so different as to cast doubt on the usefulness of the endeavor. But we had faith in the ultimate unity of population biology, and this book is the result. Now we both call ourselves biogeographers and are unable to see any real distinction between biogeography and ecology.

The Theory of Island Biogeography

Article

Jan 1967

Biometry: the principles and practice of statistics in biological research

Article

Jan 1985

Climax vegetation in tropical America

Article

Jan 1944

J.S. Beard

Effects of human settlement on bird communities in lowland riparian areas of Colorado (USA)

Article

Aug 2003

Riparian areas in western North America have been characterized as centers of avian diversity, yet little is known about the ways that native species in streamside habitats are affected by development nearby. To address this issue, we examined patterns of habitat use by birds during the 1995-1997 breeding seasons at 16 lowland riparian sites representing an urban-to-rural gradient. As development increased, riparian woodlands tended to have fewer native trees and shrubs, less ground and shrub cover, higher tree densities, and greater canopy closure. Bird species richness also declined as urbanization increased in the surrounding landscape. Canonical correspondence analysis (CCA) revealed that measures of settlement intensity best explained variation in habitat use by riparian birds, although some residual variation was accounted for by differences in woodland understory features. Migrant and low-nesting species were associated with lower-than-average levels of development, whereas resident and cavity-nesting species tended to increase with urbanization. In partial CCA analyses, however, local habitat variables explained twice the variation that measures of settlement did; nearly half of all explained variation could be attributed to local and landscape variables simultaneously. For avian guilds based on migratory, nesting, and foraging behavior, regression analyses showed that the best variables for explaining patterns of habitat use were usually those that reflected levels of urbanization, particularly at broad scales. When the effects of local habitat variation were removed, however, the best variables for explaining residual variation in habitat use tended to describe development at relatively fine scales, especially for species that nested or foraged low for insects or seeds. These species were also the most sensitive to human trail use. Our analyses indicated that bird communities and local habitat conditions in riparian areas were both affected by development in the surrounding landscape. It may be possible to mitigate the negative impacts of human settlement on native birds in streamside woodlands by maintaining or restoring vegetation structure and composition, and by imposing limits on human recreational activity in these habitats.

Jamaica: Test Case for Tropical Deforestation?

Article

Jan 1987

L.A. Eyre

Deforestation in Jamaica, according to the United Nations (FAO/UNEP) and other sources, is occurring at an annual rate of about 3%. The Ministry of Agriculture claims that the national forested area is actually increasing rapidly. A survey of humid tropical forests in Jamaica, carried out by the author in 1986, indicates a 3.3% per annum rate of deforestation for 1980-1986. But, despite significant commercial lumber production, large clear fellings are rare and most modification of the forest is due to expansion of small-scale farming (including Cannabis sativa) and pastoral activity. As uncontrolled deforestation is adversely affecting watersheds and inducing serious flooding, some form of control and management is urgently required.-from Author

Butterfly Metapopulation Dynamics

Chapter

Dec 1995

This chapter discusses butterfly metapopulation dynamics. The metapopulation concept is swiftly spreading into common usage in population and conservation biology. The term “metapopulation” itself is not new, as it was coined by Richard Levins, 25 years ago. It took 20 years before biologists at large began to employ it. The model is based on a generalized incidence function and it provides a simple yet realistic and practical means of modeling real metapopulations. Melitaea cinxia is one of the many European butterflies that have declined during the past decades. More than half of the species not forming local populations failed also to satisfy the second condition, because they have large “mainland” populations. During the past 10 years the metapopulation approach has been applied in several butterfly studies in both North America and Europe. Migration between habitat patches is a key process in metapopulation dynamics. It is not generally agreed that metapopulation dynamics in the sense described in this chapter are often critical for long-term persistence of butterflies and other taxa. It is difficult to disagree about rampant environmental changes, and it is equally clear that many populations have been exterminated because the habitat became unsuitable. Melitaea cinxia may be exceptional, but until a score of other equally comprehensive studies have been completed, there is no reason to rush to a general conclusion.

Data analysis and graphics using R – An example-based approach, Third edition

Book

Jan 2007

Discover what you can do with R! Introducing the R system, covering standard regression methods, then tackling more advanced topics, this book guides users through the practical, powerful tools that the R system provides. The emphasis is on hands-on analysis, graphical display, and interpretation of data. The many worked examples, from real-world research, are accompanied by commentary on what is done and why. The companion website has code and datasets, allowing readers to reproduce all analyses, along with solutions to selected exercises and updates. Assuming basic statistical knowledge and some experience with data analysis (but not R), the book is ideal for research scientists, final-year undergraduate or graduate-level students of applied statistics, and practising statisticians. It is both for learning and for reference. This third edition expands upon topics such as Bayesian inference for regression, errors in variables, generalized linear mixed models, and random forests. © Cambridge University Press 2003 and John Maindonald and W. John Braun 2007, 2010.

Effects of Forest Fragmentation on Understory Hummingbirds in Amazonian Brazil

Article

Oct 1995

We sampled understory hummingbirds in Amazonian forest fragments from before isolation through nine yeats after isolation We recorded 377 captures of eight species in five I-ha fragments and four 10-ha fragments. The three species netted before isolation Phaethornis superciliosus, Phaethornis bourcieri, and Thalurania furcata, were nearly equally abundant at that time. After isolation abundance of P. bourcieri and T. furcata did not change, but P. superciliosus became nearly twice as common. Five additional species that were netted only after isolation represented about 10% of the post-isolation sample. The species recorded only after isolation were forest species usually found above the levels of nets;fragments were not colonized by nonforest species. Use of fragments did not differ between 1- and 10-ha fragments. The landscape surrounding the fragments included active cattle pasture, abandoned pasture, and Cecropia-dominated second growth, but this variation had little effect on use of fragments by hummingbirds. The results suggest that these understory hummingbirds can persist in a matric of fragments, secondary growth, and large forest patches. This response is much different than that of the insectivorous birds that dominate the understory bird community at the site, which are much more vulnerable to fragmentation.

Variation in Local-Scale Edge Effects: Mechanisms and Landscape Context

Article

Oct 1997

Ecological processes near habitat edges often differ from processes away from edges. Yet, the generality of ''edge effects'' has been hotly debated because results vary tremendously. To understand the factors responsible for this variation, we described nest predation and cowbird distribution patterns in forest edge and forest core habitats on 36 randomly selected plots in three states in the midwestern United States. We tested four hypotheses that may explain the variation and mechanisms responsible for edge effects among the 36 plots: (1) the landscape context, (2) the local predator community, (3) the local bird (host-prey) community, and (4) the nest site microhabitat structure. We used artificial nests baited with quail and clay eggs to determine nest predation patterns and predators and used point count surveys to determine cowbird and host abundance in forest edge and forest core habitats. Raccoons, opossums, canids, and birds accounted for most predation of artificial nests. Neither local host abundance nor mean nest concealment of artificial nests significantly influenced nest predation rates in habitat edge or in habitat core. Nest predation was significantly greater in highly fragmented landscapes than in unfragmented landscapes and was significantly higher in edge habitats than in core habitats. However, detection of edge effects varied, depending upon landscape type. Higher predation rates in edge habitats were detected in highly and moderately fragmented landscapes, but not in unfragmented landscapes. Both mammalian and avian predator groups contributed to higher predation rates along edges in highly and moderately fragmented landscapes. Cowbird abundance was significantly related to host abundance, but the effect of hosts varied depending upon habitat type. In edge habitats, cowbird abundance was negatively associated with host abundance in all three landscapes studied. By contrast, cowbird abundance was positively associated with host abundance in core habitats. Once the effects of host abundance were removed, cowbird abundance in core habitat was greater in highly fragmented landscapes than in moderately and unfragmented landscapes, but did not differ between the latter two. In edge habitat, cowbird abundance did not differ between landscapes, but abundance in edges tended to be highest in the highly fragmented landscape and lowest in the unfragmented landscape. Cowbird abundance did not vary between edge and core habitat in any of the landscapes studied. We suggest that the first approximation to predicting the impact of agricultural or permanently managed edges on forest songbird reproductive success is to assess habitat characteristics at the landscape scale. Given geographic location, local factors such as host abundance and predator composition should be assessed.

The Analysis of Contingency Tables

Article

Aug 1978

Land Mosaics: The Ecology of Landscapes and Regions.

Article

Oct 1996

Bird Activity and Seed Dispersal of a Montane Forest Tree (Dunalia arborescens) in Jamaica

Article

Jun 1981

Alexander Cruz

The dispersal system of the neotropical tree Dunalia arborescens (Solanaceae) was examined in a montane mist forest in Jamaica. A total of 16 species of birds representing 14 genera and eight families were recorded feeding on D. arborescens fruits. The most common species feeding were the stripe-headed tanager (Spindalis zena), greater antillean bullfinch (Loxigilla violacea), and the rufous-throated solitaire (Myadestes genibarbis), accounting for 66 percent of the total visits. Intraspecific encounters dominated actions, and interspecific interactions were minimal, the latter was probably due to a superabundance of food and, to a lesser degree, to differences in foraging and feeding behavior. In general, birds arrived and left the feeding tree as individuals or as groups of several individuals of one species. No mixed species flocks were observed arriving or leaving the fruiting tree. Observations on color-marked individuals and on all species feeding on D. arborescens showed that the amount of fruit dependency varied from almost 100 percent in the stripe-headed tanager and the greater antillean bullfinch to less than 30 percent in the greater antillean elaenia (Elaenia fallax) and the jamaican oriole (Icterus leucopteryx). The birds involved exploited a variety of fruits throughout the year, but at any one time ate fruit of a few species. What determined the diet at any one time depended on the fruiting phenology, commonness of tree, large crop size, and individual preferences. The fruiting period of the different feeding trees in the study area ranged from complete overlap to no overlap; as the number of fruits of one species decreased, the number of another species increased. Staggered fruiting may enable these trees to take advantage of the same bird populations at different times and thus relieve competition for seed dispersers. The high reproductive potential of D. arborescens expressed in the abundance of fruits with many seeds, and the presence of a number of different dispersers of widely different sizes, degree of dependency on fruits and foraging behavior suggest that this tree is opportunistic in nature. It is a species found in forest edges, clearings, and other habitats that are spatially unpredictable. Premium is placed in the dispersal of seeds as widely as possible by the greatest variety of dispersers, because the tree's survival depends upon the rapidity with which it can colonize bare ground and gaps in the primary forest.

Structure and Organization of an Amazonian Forest Bird Community

Article

Jun 1990

To help fill the gap in detailed knowledge of avian community structure in tropical forests, we undertook a census of a 97-ha plot of floodplain forest in Amazonian Peru. The plot was censused over a 3-mo period spanning the 1982 breeding season. The cooperative venture entailed @?12 person-months of effort. Conventional spot-mapping was the principal method used, but several additional methods were required to estimate the numbers of non-territorial and group-living species: direct counts of the members of mixed flocks, saturation mist-netting of the entire plot, opportunistic visual registrations at fruiting trees, determination of the average size of parrot flocks, color banding of colonial icterids, etc. Two hundred forty-five resident species were found to hold territories on the plot, or to occupy all or part of it. Seventy-four additional species were detected as occasional-to-frequent visitors, wanderers from other habitats, or as migrants from both hemispheres. By superimposing territory maps or the areas of occupancy of individual species, we determined that point (alpha) diversities exceeded 160 species in portions of the plot. About 1910 individual birds nested in 100 ha of this floodplain forest, making up a biomass conservatively estimated at 190 kg/km^2. The total number of breeding birds was equivalent to that in many temperate forests, but the biomass was about five times as great. Predominantly terrestrial granivores contributed the largest component of the biomass (39%), followed by largely arboreal frugivores (22%). Considering only insectivores, the biomass (34 kg/km^2) is somewhat less than that in the forest at Hubbard Brook, New Hampshire (40 kg/km^2), although it is greater (55 kg/km^2) if one includes omnivores. The number of insectivores was considerably less than at Hubbard Brook, due to their 60% larger average body size (32 vs. 20 g). Even though a large majority of the species were patchily distributed, the 97-ha plot was found to include 99% of the bird species that regularly occupy mature floodplain forest at Cocha Cashu. The most abundant species occupied territories of 4-5 ha, and 84 species (26%) had population densities of @<1 pair per square kilometre. Of these, 33 (10% of the total community) were judged to be constitutively rare (i.e., having low population densities everywhere), rather than being merely locally rare. Many of these are predicted to be vulnerable to forest fragmentation and disturbance. Comparison of these results with those from other tropical forests proved difficult due to a lack of standardized methodology.

Land-Use Choices: Balancing Human Needs and Ecosystem Function

Article

Jun 2004

Conversion of land to grow crops, raise animals, obtain timber, and build cities is one of the foundations of human civilization. While land use provides these essential ecosystem goods, it alters a range of other ecosystem functions, such as the provisioning of freshwater, regulation of climate and biogeochemical cycles, and maintenance of soil fertility. It also alters habitat for biological diversity. Balancing the inherent trade-offs between satisfying immediate human needs and maintaining other ecosystem functions requires quantitative knowledge about ecosystem responses to land use. These responses vary according to the type of land-use change and the ecological setting, and have local, short-term as well as global, long-term effects. Land-use decisions ultimately weigh the need to satisfy human demands and the unintended ecosystem responses based on societal values, but ecological knowledge can provide a basis for assessing the trade-offs.

Numerical Ecology

Book

Jan 1998

The chapter introduces the idea that the relationships between natural conditions and the outcome of an observation may be deterministic, random, strategic or chaotic, and that numerical ecology addresses the second type of data; it describes the role of numerical ecology among the various phases of an ecological research. The chapter includes discussion of the following topics: spatial structure, spatial dependence, and spatial correlation (independent observations, independent descriptors, linear independence, independent variable of a model, independent samples, origin of spatial structures, tests of significance in the presence of spatial correlation, and classical sampling and spatial structure), statistical testing by permutation (classical tests of significance, permutation tests, alternative types of permutation tests), computer programs and packages, ecological descriptors (i.e. variables: mathematical types of descriptors, and intensive, extensive, additive, and non-additive descriptors), descriptor coding (linear transformation, nonlinear transformations, combining descriptors, ranging and standardization, implicit transformation in association coefficients, normalization, dummy variable coding, and treatment of missing data (delete rows or columns, accommodate algorithms to missing data, estimate missing values). The chapter ends on a description of relevant software implemented in the R language.

Influence of Landscape Composition on Avian Community Structure and Associated Mechanisms

Article

Dec 2001

Many recent studies have addressed the effects of patch size and isolation on bird communities in highly fragmented landscapes, but the importance of landscape composition in more forested landscapes remains poorly understood. The objectives of our study were (1) to determine the effects of two structurally and temporally distinct disturbance types (agriculture and silviculture) and extent of disturbance (percentage of disturbance within 1.0 km) on avian community structure within forested landscapes, and (2) to investigate underlying mechanisms responsible for associations between landscape composition and avian communities. Differences in microhabitat, microclimate, and nesting success among landscapes were examined as possible mechanisms. Breeding bird communities in central Pennsylvania (USA) were surveyed twice per year during 1997-1999 at 34 sites within contiguous mature forest, which represented a range of disturbance extent (4-59% nonforest cover within 1.0 km). Each site was in a forested landscape containing predominantly agricultural or silvicultural disturbances (n = 17 each). Our results indicate that type of disturbance within landscapes influenced bird community composition and relative abundance more than extent of disturbance. Compared to forests within landscapes disturbed by silviculture, forests within landscapes disturbed by agriculture, irrespective of the extent of disturbance, had fewer forest-associated species, long-distance migrants, forest-canopy and forest-understory-nesting species, and greater numbers of edge-associated species, including avian nest predators and Brown-headed Cowbirds (Molothrus ater). Fewer species and guilds were associated with the extent of disturbance within a landscape or interactions between disturbance type and extent. Abundances of edge-associated species, residents, and forest-canopy nesters increased with increasing amounts of disturbance within forested landscapes. Local variation in microhabitat and microclimate among landscapes did not explain observed differences in avian community structure. However, nesting success was greater and numbers of some avian and small mammalian nest predators were lower in stands within forested landscapes disturbed by silviculture than in forested landscapes disturbed by agriculture. Nesting success was not associated with the extent of a given disturbance type within landscapes. These results demonstrate that, even within forested landscapes, the types of disturbance can influence avian community structure and, thus, should be considered in conservation and forest management plans. In particular, agricultural disturbances within forested landscapes seemed to negatively affect bird communities in adjacent forests more than silvicultural disturbances. Both species richness and abundance of forest-associated species were greater on sites with higher levels of nesting success. Thus, differences in nesting success resulting from altered interactions between nest predators and nesting birds may be an important underlying mechanism of avian community structure and organization at the landscape scale.

The Vegetation of Jamaica

Article

Oct 1953

The Classification of Tropical American Vegetation-Types

Article

Jan 1955

J. S. Beard

Avian Ecology and Conservation in An Urbanizing World

Book

Jan 2001

Permutation Methods: A Distance Function Approach

Book

Jan 2007

The Importance of Land Uses within the Landscape Matrix

Article

Jun 2003

Amanda D. Rodewald

Significant changes in land-use practices, combined with increasing levels of fragmentation within the last century, have made the landscape an important and relevant scale for studies of wildlife ecology and management. However, relatively few landscape-level investigations have explicitly addressed characteristics of the landscape matrix. Even fewer studies have examined how specific land uses within the matrix affect wildlife, and most of these confound the amount and type of disturbances within study designs. Recent research demonstrates that land uses can differ markedly in their effects on wildlife in near-by forests or grasslands-even in landscapes with comparable amounts of habitat. In particular, urban or residential development within the matrix can alter diversity or abundance of some species and can depress avian nesting success even in large forest tracts. Simply the presence of certain land uses, such as agricultural openings, within forested regions can negatively impact some animal communities. Collectively, these studies provide strong evidence that land uses within forested and fragmented landscapes are important influences on wildlife populations and communities. Consequently, biologists and managers involved in the design and management of natural areas, parks, reserves, and other public lands should carefully consider types of land uses occurring within or adjacent to their boundaries.

Hanski I. Metapopulation dynamics. Nature 396: 41-49

Article

Nov 1998

Ilkka Hanski

Metapopulation biology is concerned with the dynamic consequences of migration among local populations and the conditions of regional persistence of species with unstable local populations. Well established effects of habitat patch area and isolation on migration, colonization and population extinction have now become integrated with classic metapopulation dynamics. This has led to models that can be used to predict the movement patterns of individuals, the dynamics of species, and the distributional patterns in multispecies communities in real fragmented landscapes.

vegan: Community Ecology Package. R Package Version 1.13-2

Article

Jan 2008

Model Selection and Multimodel Inference: A Practical Information-Theoretic Approach

Book

Jan 2002

Not seeing the ocean for the islands: The mediating influence of matrix-based processes on forest fragmentation effects

Article

Jan 2006
GLOBAL ECOL BIOGEOGR

The pervasive influence of island biogeography theory on forest fragmentation research has often led to a misleading conceptualization of landscapes as areas of forest/habitat and 'non-forest/non-habitat' and an overriding focus on processes within forest remnants at the expense of research in the human-modified matrix. The matrix, however, may be neither uniformly unsuitable as habitat nor serve as a fully-absorbing barrier to the dispersal of forest taxa. In this paper, we present a conceptual model that addresses how forest habitat loss and fragmentation affect biodiversity through reduction of the resource base, subdivision of populations, alterations of species interactions and disturbance regimes, modifications of micro- climate and increases in the presence of invasive species and human pressures on remnants. While we acknowledge the importance of changes associated with the forest remnants themselves (e.g. decreased forest area and increased isolation of forest patches), we stress that the extent, intensity and permanence of alterations to the matrix will have an overriding influence on area and isolation effects and emphasize the potential roles of the matrix as not only a barrier but also as habitat, source and conduit. Our intention is to argue for shifting the examination of forest fragmentation effects away from a patch-based perspective focused on factors such as patch area and distance metrics to a landscape mosaic perspective that recognizes the importance of gradients in habitat conditions.

Twenty years of understorey bird extinctions from Amazonian rain forest fragments: Consistent trends and landscape-mediated dynamics

Article

Jan 2009

Aim We analysed presence/absence data for understorey bird species in rain forest fragments sampled from 1979 through 2001. Here we consider extinctions between 1992, when most fragments had been isolated for at least 8 years, and 2001. Our objectives were to determine whether high extinction rates documented soon after isolation continued through up to 20 years after isolation, and to examine fragment size and landscape effects on extinction. Location Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. Methods Through 1992, birds were surveyed with standardized mist net sampling in ten 1- to 100-ha fragments. We repeated the mist net protocol in 2000–01. We also added remote taping of the dawn chorus and tape playback surveys for species captured in 1991–92 but not in 2000–01. Results Between 1992 and 2001, 37 species went extinct in at least one fragment. As expected, extinction rate decreased with increasing fragment size. Over 30% of species went extinct in 1-ha fragments, compared to about 5% in 100-ha fragments. Extinction followed a predictable pattern: most species lost from 100-ha fragments between 1992 and 2001 had already gone extinct in smaller fragments before 1992. Despite extinctions, fragments gained species between 1992 and 2001, apparently due to species moving through the developing second growth matrix. Fragments surrounded by old second growth had lower extinction rates than predicted based on fragment size alone. Main conclusions Sequential extinctions occurred for at least 20 years. Some additional species previously lost from smaller fragments may continue to go extinct in 100-ha fragments. At the same time, species assemblages in 1- and 10-ha fragments mostly reflect second-growth dynamics by 20 years after isolation. High species loss predicted from the first few years after isolation has not occurred, almost certainly because of recolonization.

Ecological Correlates of Extinction Proneness in Australian Tropical Rain Forest Mammals

Article

Mar 1991
CONSERV BIOL

William F. Laurance

There is a dire need to predict the vulnerability of tropical forest biotas to habitat fragmentation I tested the efficacy of seven ecological traits (body size Iongeuity, fecundity, trophic level, dietary specialization, natural abundance in rain forest and abundance in the surrounding habitat matrix) for predicting responses of 16 nonflying mammal species to rain forest fragmentation in tropical QueenslaM Australia An ordination analysis revealed that most (84%) of the variation in traits was described by two axes, the first separating rand K‐selected species, and the second discriminating rare species with specialized diets from common species with generalized diets. Using multiple regression analysis, the two ordination axes explained 51.7% of variation in mammal extinction proneness (F = 9.96 P = 0.009). Howem, univariate tests revealed tbat a single trait abundance in the mawas a betterpredictor of vulnerability (r ² = 63.8%, F = 24.69, P < 0.001). Partial correlations demonstrated that once the effects of matrix abundance tuete remove4 no other traits or ordination axes were significant predictors of extinction proneness. These results highlight the importance of tolerance of modijied habitats in determining survival of nonpying mammals in tropical forest fragments. Species tbat traverse or exploit modaxied habitats tend to remain stable or inmase in fragments whereas those tbat avoid these habitats often disappem The implications of these findings for hopical forest conservation are discussed.

Habitat area requirements of breeding forest birds of the middle Atlantic states USA

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Jan 1989
WILDLIFE MONOGR

A Guide to The Birds of the West Indies

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Jan 1998

Demographic responses to habitat fragmentation

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Jan 2006
Acta Zoolog Sin

Landscape matrix and species traits mediate responses of Neotropical resident birds to forest fragmentation in Jamaica

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