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![Species richness [frugivore species 30 min −1 tree −1 ] (A), abundance [frugivore individuals 30 min −1 tree −1 ] (B) and fruits](profile/Nina-Farwig/publication/249656966/figure/fig1/AS:341391449313285@1458405472486/Species-richness-frugivore-species-30-min-1-tree-1-A-abundance-frugivore.png)
Species richness [frugivore species 30 min −1 tree −1 ] (A), abundance [frugivore individuals 30 min −1 tree −1 ] (B) and fruits
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![Fig. 2. Species richness [frugivore species 30 min −1 tree −1 ] (A),...](profile/Nina-Farwig/publication/249656966/figure/fig1/AS:341391449313285@1458405472486/Species-richness-frugivore-species-30-min-1-tree-1-A-abundance-frugivore_Q320.jpg)
So far, it is poorly understood how differential responses of avian seed dispersers and fruit predators to changes in habitat structure and fruit abundance along land-use gradients may translate into consequences for the seed dispersal of associated plants. We selected a gradient of habitat modification (forest, semi-natural, and rural habitat) cha...
Contexts in source publication
Context 1
... accounted for 67% and fruit predators accounted for 33% of visits to S. aucuparia trees (16% seed predators and 17% pulp predators). Species richness (F 2,15 = 8.42, p = 0.0035), abundance (F 2,15 = 7.46, p = 0.0056) and fruit removal rate (F 2,15 = 4.08, p = 0.039) of seed dispersers decreased from forest to semi-natural to rural habitats (Fig. 2). At the same time, species richness (F 2,15 = 0.30, p = 0.75), abundance (F 2,15 < 0.1, p = 0.93) and fruit removal rate (F 2,15 < 0.1, p = 0.92) of fruit predators did not vary among habitats. Consequently, the proportion of fruits removed by seed dispersers tended to decrease from 90% (+5.7/−7.6) (back- transformed mean ± SE) in ...
Context 2
... effects of fruit abundance and tree cover, we introduced these covariates into the preceding models. Species richness and abundance of seed dispersers increased with an increase in tree cover, while fruit removal rate and the proportion of fruits removed by seed dispersers increased with an increase in fruit abundance (see Appendix A: Table S1; Fig. S2). After inclusion of tree cover and fruit abundance, habitat was not significant anymore in explaining variation in any of the models (see Appendix A: Table S1). Com- parisons of all multiple models based upon AIC c revealed that tree cover best explained variation in species richness (r 2 = 0.52, F 1,16 = 17.5, p < 0.001) and ...
Context 3
... abun- dance of seed dispersers indirectly via its effect on tree cover, while fruit removal and the proportion of fruits removed by seed dispersers were influenced via the effect on fruit abun- dance. Species richness, abundance and fruit removal rate of fruit predators did not vary with fruit abundance or tree cover (see Appendix A: Table S1; Fig. ...
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Citations
... In this later case, the cost of transporting acorns from the shrubland to the forest (e.g., higher time, energy expenditure and predation risk during transport) probably does not compensate for the lower jay predation risk provided by the forest to hide acorns. As shown for other forest frugivorous species (García and Ortiz-Pulido, 2004;Albrecht et al., 2012), acorn dispersal in the shrubland by jays may be driven by acorn production because isolated trees usually have higher seed production than forest trees (Pausas et al., 2009;Morán-López et al., 2015). It is possible that habitat selection by jays and the spatial dispersal pattern observed in this study can also be influenced by acorn caching territories, mainly in the forest around theirs nests, as demonstrated in another corvid, the magpie (Martínez- Baroja et al., 2021). ...
Seed dispersal is key to forest regeneration and often depends on the behaviour of seed scatter-hoarding animals. However, our understanding of the decision-making of scatter-hoarders and how vegetation structure at different spatial scales affects dispersal patterns remains limited. We studied seed dispersal at the forest edge across multiple spatial scales (habitat, sub-habitat, microsites) between and within habitats with distinct vegetation structure. Our model system is an oak forest dominated by holm oak (Quercus ilex) and an adjacent shrubland dominated by the shrub Retama sphaerocarpa. For three years, we tracked the movement of acorns by a keystone scatter-hoarder, the Eurasian jay (Garrulus glandarius). At the coarse scale, jays did not show a preference for caching acorns either in the forest or in the shrubland when the source tree was within the forest. However, when the source tree was on the forest edge or was an isolated oak tree in the shrubland at < 200 m from the forest, jays showed a preference for caching in the forest. Conversely, when isolated oak trees were > 200 m from the forest, all acorns were dispersed in the shrubland. Dispersal distances were shorter within the forest than within the shrubland. At an intermediate scale, within the shrubland jays preferred to cache acorns under large retamas while avoiding gaps. In the forest, jays also avoided gaps and preferred certain woody species and vertical vegetation structures, although these preferences varied across feeders. At the finest scale, jays selected stones as cache microsites. Thus, the selection of acorn caching sites followed a hierarchical and selective top-down process across different spatial scales. The position of the source trees in the landscape determined habitat preference and dispersal distance. We detected different preferences in response to similar vegetation structure and composition, indicating that the decision-making process is flexible at an intermediate scale that generates diverse spatial patterns of dispersal. This study sheds light on the intricate decision-making process of seed caching by scatter-hoarders, and the consequences for the spatial patterns of seed dispersal as well as the expansion and regeneration of oak forests.
... In a foraging context, red can be a positive or negative signal. In fruits, red signals profitability (Schaefer and Schaefer 2006;Albrecht et al. 2012), but in insects, it can signal unprofitability, as with aposematic prey (Majerus 2016). Herein lies a problem for naive signal receivers-how to distinguish between profitability and unprofitability when the colour signal is the same. ...
Many animals express unlearned colour preferences that depend on the context in which signals are encountered. These colour biases may have evolved in response to the signalling system to which they relate. For example, many aposematic animals advertise their unprofitability with red warning signals. Predators' innate biases against these warning colours have been suggested as one of the potential explanations for the initial evolution of aposematism. It is unclear, however, whether unlearned colour preferences reported in a number of species is truly an innate behaviour or whether it is based on prior experience. We tested the spontaneous colour and shape preferences of dark-hatched, unfed, and visually naive domestic chicks (Gallus gallus). In four experiments, we presented chicks with a choice between either red (a colour typically associated with warning patterns) or green (a colour associated with palatable cryptic prey), volume-matched spheres (representing a generalised fruit shape) or frogs (representing an aposematic animal's shape). Chicks innately preferred green stimuli and avoided red. Chicks also preferred the shape of a frog over a sphere when both stimuli were green. However, no preference for frogs over spheres was present when stimuli were red. Male chicks that experienced a bitter taste of quinine immediately before the preference test showed a higher preference for green frog-shaped stimuli. Our results suggest that newly hatched chicks innately integrate colour and shape cues during decision making, and that this can be augmented by other sensory experiences. Innate and experience-based behaviour could confer a fitness advantage to novel aposematic prey, and favour the initial evolution of conspicuous colouration.
... Additionally, when there is greater production of fruits, more visits of fruit eaters are expected. So, it seems that it could be important in future studies to evaluate productivity as predictor of the amount of seed dispersion, as has been observed in other studies (Albrecht et al. 2012;Hampe, 2008). ...
Introduction: Much has been argued about the importance of the role that different types of frugivores play as seed dispersers in plant communities, but few studies have been actually carried out. Objective: We evaluated and compared diurnal and nocturnal seed dispersal in a primary and secondary sub-Andean forest in Southern Colombia. Methods: We estimated number and biomass (kg/ha) of seeds dispersed over one year (2017) using 60 fruit traps that were checked before sunrise and before sunset for 10 continuous days every two months. Results: We found that from 1 874 dispersed seeds, 55.8 % (10.9 kg/ha) were collected during the day and 44.2 % (6.39 kg/ha) at night. There were no significant differences between diurnal and nocturnal seed dispersal in number of seeds or biomass. We also found no difference in between seed dispersal that in the primary forest and secondary forest over time. Within diurnal organisms, primates and fruit-eating birds appear to be primarily responsible for this ecosystem service during the day; while bats, birds (e.g. oilbirds), and probably primates did so during the night. Conclusions: Diurnal and nocturnal dispersal seem to be equal in terms of number and weight of seeds, but not in the similarity of dispersed plant species. It remains a challenge to recognize the relative importance of different fruit-eating organisms as seed dispersers using fruit trap methods.
... Stumps in complex stands with lower average canopy heights further increased the probability of seed deposition. Frugivore assembly and habitat use, and associated seed deposition can be strongly influenced by changes in local habitat structure (Schupp et al., 2010;Albrecht et al., 2012). Habitats with higher bird densities generally have higher seed deposition (Garcia et al., 2010). ...
... Foliage height diversity is an important driver of bird abundance and richness (Baril et al., 2011;Sam et al., 2019), because structurally complex forests provide a greater variety of microhabitats that offer diverse roosting, foraging and nesting opportunities (MacArthur and MacArthur, 1961;Garcia et al., 2010). Also, fruit removal is often resource-driven (Albrecht et al., 2012). Stands of Norway spruce in our study area have low complexity and low berry production, and are therefore probably not the most attractive habitats for frugivorous birds. ...
Berry-producing Vaccinium shrubs are keystone species in boreal forest ecosystems and their berries provide an essential food source for many vertebrates. In Fennoscandia, both the abundance and cover of Vaccinium have decreased in forests, with intensive forestry practice as a main driver. Vaccinium seedling recruitment is constricted to recruitment windows of opportunity and appears to be infrequent, mainly due to seed dispersal limitation. Passerine birds are key players in seed dispersal, which can be directed towards perching points such as coarse woody debris. In this study, we investigated the potential for directed endozoochory by passerine birds towards cut stumps and if such stumps were viable recruitment windows for Vaccinium species, in an intensively managed boreal forest landscape of central Norway. We surveyed stump and paired forest floor microsites for passerine scat (i.e. potential seed rain) and Vaccinium seedlings. We collected passerine scat and conducted germination experiments to assess if they contained viable seed. We tested the microsite effect (i.e. forest floor/stump) on scat deposition and seedling establishment and then used modified ensemble classifiers to identify important environmental factors affecting scat deposition and seedling establishment patterns. We found that passerine scat was disproportionally deposited on stumps, and that the vast majority of scat contained viable Vaccinium seed. Stumps were also suitable recruitment windows for Vaccinium species, as a higher probability of seedling establishment occurred at stumps compared with the forest floor. However, scat deposition and seedling establishment at stumps were rather contextual and determined by environmental variables. The probability of scat deposition increased with higher complexity of the vertical forest structure and lower canopy cover, whereas seedling establishment required bryophyte cover and larger stumps, or alternatively smaller stumps with competition-free spaces. Our results highlight a pathway to successful sexual reproduction for Vaccinium species in managed forests: passerine birds direct endozoochorous seed dispersal towards tree stumps, which can offer suitable conditions for seedling establishment. However, the spatiotemporal variability both in forest stand structure and in stump conditions have a strong influence on the success of sexual recruitment via this pathway.
... We predicted that avian seed dispersal networks in the urban ecosystem are highly specialised and therefore weakly structured. Effectively, this means that avian seed dispersal networks in urban ecosystems are not robust to species extinction as compared to those reported in the wild tropical and subtropical ecosystems (Albrecht et al. 2012;Dugger et al. 2018). ...
... All fruit-eating birds on each focal fruiting plant were observed for a period of 30 min, before moving to the next plant within the 5 h' time per day (Albrecht et al. 2012). Thus, each plant was observed for a total of 1.5 h (i.e. 30 min/day × 3 observation days). ...
Animal seed dispersal processes are an important aspect of ecosystem services, as they shape the survival of seed dispersers and the balanced distribution of propagules for many plant communities. Several studies within tropical wild ecosystems have generally shown that seed dispersal processes are highly generalised and robust to extinction. Studies examining seed dispersal networks in highly built-up urban ecosystems and their robustness to species loss or extinction are rare. We examined avian seed dispersal networks across an urban ecosystem characterised by a high human settlement and infrastructure of the built environment in Zambia to determine their network specialisation, interaction evenness and interaction diversity, as these three parameters are critical in driving the resilience of these mutualisms’ interactions against extinction. A total of 405 individuals representing 11 species of birds were observed and recorded feeding on a total of 11 focal fleshy-fruiting plant species. Network specialisation was generally low and remained similar across study areas. Interaction evenness and interaction diversity were not only high but also remained similar across study areas. Low specialisation and high interaction evenness and diversity show that mutualistic interactions in these networks are equally highly generalised, suggesting a stable and robust coexistence of species in plant–frugivore communities within urban ecosystems. Generally, our results seem to broadly suggest that opportunities for conservation still exist in these ecosystems provided urbanisation is accompanied by promoting either the management of remnant fruiting plants or the cultivation of new ones to support the avian communities existing in these areas.
... Rowan seeds are dispersed by frugivorous animals, mainly birds (Raspé et al., 2000, Guitián & Munilla, 2010, Albrecht et al., 2012. Seed passage through bird guts increases rowan germination rate and seedling growth (Paulsen & Hogstedt, 2002). ...
The animal dispersal hypothesis predicts that mast seeding can increase dispersal rate of seeds by dispersers and enhance reproductive success of plants. However, in contrast to pollination efficiency and predator satiation hypothesis, the animal dispersal hypothesis has received mixed support.
Using 12‐year data on fruit production and seedling recruitment of a fleshy‐fruited tree rowan (Sorbus aucuparia, Rosaceae), we tested if an increase in the fruit production at the population level results in higher proportion of fruits recruiting into seedlings. Recruitment was recorded near (under rowans) and far (under heterospecifics) from conspecifics. Higher recruitment rates under rowans would support predator satiation hypothesis. Higher recruitment rates under heterospecific trees, where fruits can only arrive with animal assistance, would support animal dispersal hypothesis.
High population‐level fruit production increased the proportion of fruits recruiting into seedlings both near and far from rowans. In contrast, high individual‐level fruit production did not have a positive effect on the proportion of fruits recruiting into seedlings.
Synthesis. Population‐level synchronisation of fruit production is required to generate a more effective plant regeneration. Our findings show that masting enhances seedling recruitment through predator satiation and increased seed dispersal by frugivores. The results provide support for both animal dispersal and predator satiation hypotheses indicating that both mechanisms can operate simultaneously.
... First, we expected that individual plants would be more connected and less specialized (i.e., interact with more bird species) in neighborhoods with higher fruit density because of enhanced seed disperser attraction (Sargent 1990;Gleditsch et al. 2017). Second, because high infrastructure cover and low tree cover reduce frugivore diversity (Souza et al. 2019;Schneiberg et al. 2020) and impact habitat suitability and food and shelter availability for birds (Albrecht et al. 2012;Rey and Alcántara 2014), we expected decreased connectivity and increased specialization under such circumstances. Third, since smaller plants with lower fruit crops and shorter fruiting duration are less likely to be detected or attractive to birds (Levey 1988;Carr 1992;Schleuning et al. 2011;Suhonen and Jokimäki 2015), we expected individuals with such characteristics to present decreased connectivity and increased specialization. ...
While network analyses have stimulated a renewed interest in understanding patterns and drivers of specialization within communities, few studies have explored specialization within populations. Thus, in plant populations, causes and consequences of individual variation in their interactions with mutualistic animals remain poorly understood. Studying a Brazilian pepper (Schinus terebinthifolia) population, we measured the extent of individual variation in interactions with seed dispersers and tested whether connectivity (number of seed dispersers) and specialization (exclusiveness of partners) are associated with phenotypic and phenological traits of individuals and their spatial context. We found that: (i) individuals varied broadly in their connectivity and specialization on seed dispersers; (ii) phenotypic traits and spatial context matter more than fruiting duration in determining how many and how exclusive are seed dispersers of an individual; (iii) the individual-based network was nested and indicated that the less connected individuals were shorter, occurred in neighborhoods with fewer fruits, and tended to interact with a subset of the partners of more generalist individuals which, in turn, were taller and inserted in higher fruit density neighborhoods; (iv) modularity indicated the existence of subsets of individuals that interacted disproportionately with distinct groups of partners, which may occur due to differences in bird habitat use across the landscape. Our study underlines a remarkable interindividual variation that is overlooked when interactions are compiled to describe species-level interactions. Traits and spatial contexts that define variation among individuals may have important implications not only for fitness but also for sampling and description of interactions at species level.
... Bird foraging sampling was performed by two experienced ornithologists using binoculars (8 × 42 mm) and monocular (60 × 70 mm) in two foraging periods of 9:00-12:00 a.m. and 14:00-17:00. The observation frequency was once a week, we ensured that all plants in the ripening stage had 30 min bird foraging records in one observation period, and the cumulative observation effort of each species of plant was 3 h during the whole experimental period [45]. The two experienced ornithologists did not change during the whole experimental period to control systematic errors, and all the field surveys were carried out on windless days with no rain. ...
Interaction between animals and plants is an important way to maintain terrestrial biodiversity and ecosystem function, but little is known about the structure of reciprocal networks between fruit plants and frugivore birds in urban habitats. To explore the characteristics of the plant–frugivore network and network roles of species, we observed the fruit ripening phenology of 21 species of fruit plants and the interactions between these plants and 39 species of frugivore birds during the whole year in a large urban park. Then, we assessed the characteristics of the total plant–frugivore and seasonal networks, and analyzed the network roles of species and the relationship between their network roles and ecological traits. Fruit ripened mainly in autumn and winter, and interaction connections in the two seasons contributed 39.68% and 44.83% to the total network, respectively. The specialization (H2′), connectance (C), nestedness, and interaction evenness (eH2) of the network were lower in autumn and winter, while the interaction diversity was higher. Compared with the networks (N = 1000) generated by the null model, the observed network exhibited higher nestedness and interaction diversity (E2) and lower specialization (H2′), connectance (C), and interaction evenness (eH2). A correlation analysis combining ecological traits and network roles showed that plants with black fruit had higher effective partners and partner diversity, while other traits of plants and birds were not significantly correlated with their network parameters. The important plants (N = 6) and birds (N = 3) contributed to 71.78% and 67.55% of the total network connection, they were mainly evergreen plants with black and red drupes and omnivorous generalist birds with medium and large sizes. Our research highlighted the seasonal differences in urban plant–frugivore network and the value of important species in maintaining network structures and providing ecosystem services.
... Stumps in complex stands with lower average canopy heights further increased the probability of seed deposition. Frugivore assembly and habitat use, and associated seed deposition can be strongly influenced by changes in local habitat structure (Schupp et al., 2010;Albrecht et al., 2012). Habitats with higher bird densities generally have higher seed deposition (Garcia et al., 2010). ...
... Foliage height diversity is an important driver of bird abundance and richness (Baril et al., 2011;Sam et al., 2019), because structurally complex forests provide a greater variety of microhabitats that offer diverse roosting, foraging and nesting opportunities (MacArthur and MacArthur, 1961;Garcia et al., 2010). Also, fruit removal is often resource-driven (Albrecht et al., 2012). Stands of Norway spruce in our study area have low complexity and low berry production, and are therefore probably not the most attractive habitats for frugivorous birds. ...
... 우리가 관찰한 팥배나무 열매 는 종 내 변이의 범위 안에 속했으며 , 특히, 수백 년 간 지속된 도시화 과정에서 외곽 지역과 차별 되는 형태 변이 양상이 관찰되었다 (Bednorz, 2007). 관련 연구에서 자연 지역의 식물 종자가 더 무거웠으며 (Fontúrbel & Medel, 2017) (Albrecht et al., 2012;Blendinger et al., 2016;Obeso & Herrera, 1994;Sobral et al., 2010), 그리고 식생과 생물다양성 보전에 대한 실행 역량을 높여야 한다. ...
Understanding the functional traits of dominant species in urban ecosystems provides insight into species' trait adaptation and ecosystem function in response to fragmented and isolated urban vegetation and reduced biological interactions. This study compared means and variances of environmental factors (geographic, meteorological, and soil attributes) and 4 leaf traits (leaf area, specific leaf area, leaf dry mass content, and leaf shape index) and 7 reproductive traits (fruit width, fruit length, fruit shape, fruit dry weight, fruit dry matter content, seed weight, and seed ratio) measured of 40 Sorbus alnifolia individuals in four mountainous areas south of Seoul downtown, South Korea. We then performed the multivariate analysis of trait combinations. While the measured environmental factors indicated the individuality of the survey sites, the urban vegetation was drier and had a longer growth period. The leaves of S. alnifolia in the urban areas were smaller and heavier, and the fruits produced longer and lighter seeds, showing the traits affected by long urbanization. The study confirmed changes in the growth and reproduction mechanism of the S. alnifolia population under the urban environment, indicating reduced biological interaction due to vegetation fragmentation and isolation. This study provides limited but distinct ecological information about the function and persistence of key species in cities with a reduced scale of biological interactions and many negative environmental factors such as air pollution.
