Brian D. Gerber

United States Geological Survey | USGS · Cooperative Research Units Program

Harvested wildlife populations should ideally be monitored to inform harvest policies and decision‐making to help achieve management objectives. When the age of harvested individuals can be obtained, these data (i.e., age‐at‐harvest data) can be used to estimate trends of abundances, demographic rates, and harvest probabilities by the statistical r...

Spatial heterogeneity in the local densities of terrestrial carnivores is driven by multiple interacting biotic and abiotic factors. Space-use patterns of large carnivores reflect the competing demands of resource selection (e.g., exploitation of habitats with abundant prey) and minimization of risks arising from human interactions. Estimating the...

SNAPSHOT USA is a multicontributor, long‐term camera trap survey designed to survey mammals across the United States. Participants are recruited through community networks and directly through a website application (https://www.snapshot-usa.org/). The growing Snapshot dataset is useful, for example, for tracking wildlife population responses to lan...

Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amo...

The social system of animals involves a complex interplay between physiology, natural history, and the environment. Long relied upon discrete categorizations of “social” and “solitary” inhibit our capacity to understand species and their interactions with the world around them. Here, we use a globally distributed camera trapping dataset to test the...

How animals use the diel period (24‐h light–dark cycle) is of fundamental importance to understand their niche. While ecological and evolutionary literature abound with discussion of diel phenotypes (e.g. diurnal, nocturnal, crepuscular, cathemeral), they lack clear and explicit quantitative definitions. As such, inference can be confounded when ev...

The proliferation of forest edges and invasive predators have been identified as two primary threats to carnivore populations globally. These threats often occur in unison, facilitated by anthropogenic activities (e.g., fragmentation), and together may pose a greater influence than when they occur separately. Targeted conservation actions for fores...

Anthropogenic developments alter the environment and resources available to wildlife communities. In response to these real or perceived threats from this development, species may adjust their spatial occurrence. Additionally, wildlife species may adjust when in diel time (24‐h light–dark cycle) they occupy sites on the landscape to adapt to changi...

How animals use the diel period (24-hour light-dark cycle) is of fundamental importance to understand their niche. While ecological and evolutionary literature abound with discussion of diel phenotypes (e.g., diurnal, nocturnal, crepuscular, cathemeral), they lack clear and explicit quantitative definitions. As such, inference can be confounded whe...

Identifying conservation actions to recover threatened species can be challenging due to many ecological uncertainties. For example, major threats to a species' conservation are commonly known or suspected, but the specific impacts on population or metapopulation dynamics can be uncertain. This is frequently the case with emerging infectious diseas...

Ongoing declines in the imperiled New England cottontail Sylvilagus transitionalis have coincided with the introduction and expansion of the closely related eastern cottontail Sylvilagus floridanus. These paired population trends have led to the inference of competition between the two species. Competition between native and introduced species has...

Tropical forests are the most species‐rich biomes in the world but suffer high rates of logging and conversion. Tropical tree‐dwelling (arboreal and semi‐arboreal) mesomammals reliant on old‐growth forest structures are especially vulnerable. The degree of behavioral arboreality of semi‐arboreal mammals can be related to forest structure and percei...

Managing wildlife populations in the face of global change requires regular data on the abundance and distribution of wild animals, but acquiring these over appropriate spatial scales in a sustainable way has proven challenging. Here we present the data from Snapshot USA 2020, a second annual national mammal survey of the USA. This project involved...

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has caused bird-population declines. Despite little change in o...

The exclusion or local extirpation of native species by exotic or introduced carnivores is a burgeoning issue for conservation. Exotic carnivores may indeed present a serious threat as they have the potential to negatively influence and/or interact with native wildlife via exploitative or interference competition, intraguild predation and/or transm...

Reduced food availability is implicated in declines in avian aerial insectivores, but the effect of nutritional stress on mammalian aerial insectivores is unclear. Unlike birds, insectivorous bats provision their young through lactation, which might protect nursing juveniles when prey availability is low but could increase the energetic burden on l...

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has caused bird-population declines. Despite little change in o...

Wildlife road mortality tends to aggregate spatially at locations commonly referred to as road mortality hotspots. Predictive models can be used to identify locations appropriate for mitigation measures that reduce road mortality. However, the influence of imperfect detection (e.g., false absences) during road mortality surveys can lead to inaccura...

Current methods to model species habitat use through space and diel time are limited. Development of such models is critical when considering rapidly changing habitats where species are forced to adapt to anthropogenic change, often by shifting their diel activity across space. We use an occupancy modeling framework to specify the multi-state diel...

Madagascar is a threatened global biodiversity hotspot and conservation priority, yet we lack broad‐scale surveys to assess biodiversity across space and time. To fill this gap, we collated camera trap surveys, capturing species occurrences within Madagascar into a single standardized database. This data set includes nine distinct protected areas o...

Time is a fundamental component of ecological processes. How animal behavior changes over time has been explored through well-known ecological theories like niche partitioning and predator-prey dynamics. Yet, changes in animal behavior within the shorter 24-hour light-dark cycle have largely gone unstudied. Understanding if an animal can adjust the...

Human developments have detrimental effects on wildlife populations globally with carnivores being particularly sensitive. The bobcat (Lynx rufus) is often considered an adaptable mesocarnivore that occurs throughout varied landcover types within its wide distribution and may be less susceptible to the negative effects of development. Our objective...

Tropical biodiversity is threatened globally by anthropogenic disturbances, particularly forest degradation and overhunting. Where large mammals have been extirpated, smaller bodied “mesomammals” may play an important ecological role (e.g., as seed dispersers). However, these species are disproportionally affected by overhunting for wildlife trade...

Habitat selection is a fundamental animal behavior that shapes a wide range of ecological processes, including animal movement, nutrient transfer, trophic dynamics and population distribution. Although habitat selection has been a focus of ecological studies for decades, technological, conceptual and methodological advances over the last 20 yr have...

Lynx rufus (Bobcat) is a wide-ranging and highly adaptable predator whose populations are increasing throughout much of its natural range including in the New England states, yet there are only limited empirical ecological studies there. How Bobcats are responding to the unique modern landscape of southern New England with its highly forested lands...

Time is a fundamental component of ecological processes. How animal behavior changes over time has been explored through well-known ecological theories like niche partitioning and predator-prey dynamics. Yet, changes in animal behavior within the shorter 24-hour light-dark cycle have largely gone unstudied. Understanding if an animal can adjust the...

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition via reliance on monoculture tree plantations. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has affected bird...

Current methods to model species habitat use through space and diel time are limited. Development of such models is critical when considering rapidly changing habitats where species are forced to adapt to anthropogenic change, often by shifting their diel activity across space. We use an occupancy modeling framework to develop a new model, the mult...

With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the Unite...

Anthropogenic habitat modification is a major driver of global biodiversity loss. In North America, one of the primary sources of habitat modification over the last 2 decades has been exploration for and production of oil and natural gas (hydrocarbon development), which has led to demographic and behavioral impacts to numerous wildlife species. Dev...

en • Madagascar’s native carnivorans are an endemic monophyletic group of eight extant species belonging to the family Eupleridae. The International Union for Conservation of Nature (IUCN) currently classifies seven of the species as threatened (Vulnerable or Endangered), as their populations are in decline due to intensifying anthropogenic pressu...

Ranging behavior is one important strategy by which nonhuman primates obtain access to resources critical to their biological maintenance and reproductive success. As most primates live in permanent social groups, their members must balance the benefits of group living with the costs of intragroup competition for resources. However, some taxa live...

ABSTRACT: Madagascar is an island nation renowned for its biodiversity and species endemism, yet it is still largely understudied, despite intense anthropogenic threats, including forest loss and edge effects. Anjanaharibe-Sud Special Reserve is a recently expanded rainforest protected area that is lacking detailed surveys and assessments of the na...

Theory predicts that species requiring multiple habitat types simultaneously should have heightened sensitivity to anthropogenic pressures, yet tests of this prediction are especially rare. We tested whether breeding site occupancy of the threatened marbled murrelet (Brachyramphus marmoratus) was driven by the synergistic effects of nesting habitat...

Significance Climate change is altering the seasonal environmental conditions to which animals have adapted, but the outcome may differ between seasons for a particular species. Demographic responses therefore need disentangling on a seasonal basis to make accurate forecasts. Our study shows that climate change is causing seasonally divergent demog...

Studies of elusive carnivores often rely on passive sampling when investigating either spatial or temporal interactions. However, inference on behavioral mechanisms are usually lacking. We present an analysis that combines previously published spatial co-occurrence estimates and temporal kernel density estimates to explore spatiotemporal interspeci...

Avian electrocutions on power poles affect raptor populations globally. Mitigation strategies in the USA are typically bottom-up, combining risk assessments for individual poles into a utility-specific avian protection plan. This approach is usually reactive, relying on incidental documentation of electrocutions for initiation, and can allow uncoor...

Ranging behavior is one important strategy by which nonhuman primates obtain access to resources critical to their biological maintenance and reproductive success. As most primates live in permanent social groups, their members must balance the benefits of group living with the costs of intragroup competition for resources. However, some taxa live...

Studies of elusive carnivores often rely on passive sampling when investigating either spatial or temporal interactions. However, inference on behavioral mechanisms are usually lacking. We present an analysis that combines previously published spatial co-occurrence estimates and temporal kernel density estimates to explore spatiotemporal interspeci...

Resource selection is often studied by ecologists interested in the environmental drivers of animal space use and movement. These studies commonly produce spatial predictions, which are of considerable utility to resource managers making habitat and population management decisions. It is thus paramount that predictions from resource selection studi...

Javan Rhinos are interesting and mysterious creatures. These rhinos used to live all throughout Northeast India and Southeast Asia. But, the rainforests they need are disappearing. This loss of their habitat, in addition to human development and hunting, are the main reasons they are now only in one spot in the world. A few scientists put on their...

Animal site fidelity structures space use, population demography and ultimately gene flow. Understanding the adaptive selection for site fidelity patterns provides a mechanistic understanding to both spatial and population processes. This can be achieved by linking space use with environmental variability (spatial and temporal) and demographic para...

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The distribution of mammals is determined by a suite of endogenous and exogenous factors. In territorial, polygynous species like tigers (Panthera tigris), males often center their space-use around female territories, repelling competitors from these areas. Competition among males for females leads to increased mortality of both sexes and infantici...

Background Characterizing animal space use is critical for understanding ecological relationships. Animal telemetry technology has revolutionized the fields of ecology and conservation biology by providing high quality spatial data on animal movement. Radio-telemetry with very high frequency (VHF) radio signals continues to be a useful technology b...

Political borders and natural boundaries of wildlife populations seldom coincide, often to the detriment of conservation objectives. Transnational monitoring of endangered carnivores is rare, but is necessary for accurate population monitoring and coordinated conservation policies. We investigate the benefits of collaboratively monitoring the abund...

Conservation and management decision making in natural resources is challenging due to numerous uncertainties and unknowns, especially relating to understanding system dynamics. Adaptive resource management (ARM) is a formal process to making logical and transparent recurrent decisions when there are uncertainties about system dynamics. Despite wid...

Characterizing animal space use is critical to understand ecological relationships. Despite many decades of using radio-telemetry to track animals and make spatial inference, there are few statistical options to handle these unique data and no synthetic framework for modeling animal location uncertainty and accounting for it in ecological models. W...

Understanding patterns of species occurrence and the processes underlying these patterns is fundamental to the study of ecology. One of the more commonly used approaches to investigate species occurrence patterns is occupancy modeling, which can account for imperfect detection of a species during surveys. In recent years, there has been a prolifera...

Animation of relationship between normal prior distributions on logit and probability scales. Probability density on probability (top panel) and untransformed (bottom panel) scale for normal priors with different values of σ2 (black boxes). (PDF)

Depiction of transformation between logit and probability scale. For each value on the x-axis, which are untransformed, the y-axis is the corresponding value that has been transformed to the probability scale. (PDF)

Supplemental results for analysis of avian occupancy. Value of variance (σ2) for mean 0 Normal prios on α and β or prior used, and posterior medians for α, β for the mature forest covariate, β for the distance (dist.) to edge covariate, and p for occupancy models fit to data from gray jays (GRJA), Steller’s jays (STJA) and song sparrows (SOSP) in t...

Supplemental results for gray jay analysis. Posterior distributions (solid lines) of α from Bayesian occupancy models with different values for σ2 on the prior for α fit to gray jay data. Maximum likelihood estimate is shown by the dashed vertical line. Panel A presents the posteriors transformed to the probability scale, which equals the estimate...

Example JAGS code to fit occupancy model with covariates. (PDF)

Example JAGS code to fit occupancy model with no covariates. (PDF)

Example JAGS code to fit occupancy model with covariates with a logistic distribution. (PDF)

Emerging infectious diseases (EIDs) are a salient threat to many animal taxa, causing local and global extinctions, altering communities and ecosystem function. The EID chytridiomycosis is a prominent driver of amphibian declines, which is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). To guide conservation policy, we developed...

Sparse detections in camera trap surveys commonly hinder density estimation for threatened species. By combining detections across multiple surveys, or using informative priors in Bayesian model fitting, researchers can improve parameter estimation from sparse capture–recapture data. Using a spatial mark–resight model that incorporates site‐level h...

1. Madagascar is home to the smallest primates in the world, the mouse lemurs (Microcebus species). Twenty-four species of mouse lemur are currently recognised and are found in variable ecosystems, from dry forests and spiny deserts to humid forests. Due to their widespread distribution and the large number of sympatric species, mouse lemurs can be...

Protected areas (PA) aim to eliminate many of the threats that species face on the greater landscape. In the last three decades, PA's have expanded considerably; however, quantitative assessments of how well they have mitigated threats to habitat and biodiversity are very limited. Habitat bordering PA's and the wildlife that use it are threatened b...

Understanding patterns of species occurrence and the processes underlying these patterns is fundamental to the study of ecology. One of the more commonly used approaches to investigate species occurrence patterns is occupancy modeling, which can account for imperfect detection of a species during surveys. In recent years, there has been a prolifera...

The effect of climate on the population dynamics of rainforest vertebrates is known only for a limited subset of species and study locations. To extend this knowledge, we carried out an 8-year population study of a Viverrid (Malay civet Viverra tangalunga) in the Wallacea biogeographical region (Buton Island, Sulawesi). Civets were trapped annually...

The Javan rhino (Rhinoceros sondaicus) is one of the most threatened mammals on Earth. The only remaining individuals live as part of a small population isolated in a single protected area, Ujung Kulon National Park, Java, Indonesia. Despite almost a century of studies, little is known about the factors that affect Javan rhino demography and distri...

Monitoring animal populations can be difficult. Limited resources often force monitoring programs to rely on unadjusted or smoothed counts as an index of abundance. Smoothing counts is commonly done using a moving average estimator to dampen sampling variation. These indices are commonly used to inform management decisions, although their reliabili...

Biological invasions can represent important threats to endemic species, including those within the invaders’ food webs. The Asian common toad (Duttaphrynus melanostictus) was introduced to Madagascar in 2011. This introduction presents a potentially dangerous prey item to a relatively naı¨ve, highly diverse endemic carnivore fauna. Using a multiva...

Decision-analytic models provide forecasts of how systems of interest will respond to management. These models can be parameterized using empirical data, but sometimes require information elicited from experts. When evaluating the effects of disease in species translocation programs, expert judgment is likely to play a role because complete empiric...

Raptor and corvid electrocutions cause continental conservation concerns for breeding, migrating, and wintering birds. Although concerns are widespread, mitigation is implemented primarily at local scales of individual electric utilities. By not considering landscape-scale patterns, conservation strategies may fail to focus mitigation where efforts...

Managing wild animal populations can be challenging. There are often uncertainties about population dynamics, the short- and long-term effects of management actions, and challenges to logistically and financially monitoring key population parameters, which can lead to uncertainty about the meaning of parameters that are monitored and result in many...

1.Prediction is fundamental to scientific inquiry and application; however, ecologists tend to favor explanatory modeling. We discuss a predictive modeling framework to evaluate ecological hypotheses and to explore novel/unobserved environmental scenarios to assist conservation and management decision makers. We apply this framework to develop an o...

Madagascar's Eupleridae carnivores are perhaps the least studied and most threatened family of Carnivora. Investigating potential direct and indirect competition among these native species and sympatric exotic carnivores is necessary to better direct conservation actions. From 2008 to 2013, we photographically surveyed a diverse rainforest landscap...

Mouse lemurs (Microcebus spp.) are an exciting new primate model for understanding human aging and disease. In captivity, Microcebus murinus develops human-like ailments of old age after five years (e.g., neurodegeneration analogous to Alzheimer's disease) but can live beyond 12 years. It is believed that wild Microcebus follow a similar pattern of...

Field-based primate studies often make population inferences using count-based indices (e.g., individuals/plot) or distance sampling; the first does not account for the probability of detection and thus can be biased, while the second requires large sample sizes to obtain precise estimates, which is difficult for many primate studies. We discuss ph...

Motion-activated cameras are a versatile tool that wildlife biologists can use for sampling wild animal populations to estimate species occurrence. Occupancy modelling provides a flexible framework for the analysis of these data; explicitly recognizing that given a species occupies an area the probability of detecting it is often less than one. Des...