Richard B. Chandler's research while affiliated with University of Georgia and other places

Publications (122)

Article
Peripheral populations of ruffed grouse Bonasa umbellus at the trailing edge of their range are likely to be at risk of population declines and potential extirpation from continued climate and habitat change. Accurate estimates of abundance and distribution are needed for peripheral populations to inform management decisions. We show that ruffed gr...
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Large carnivore restoration programs are often promoted as capable of providing ecosystem services. However, these programs rarely measure effects of successful restoration on other economically and ecologically important species. In South Florida, while the endangered Florida panther Puma concolor coryi population has increased in recent years due...
Article
Long‐term monitoring is an important component of effective wildlife conservation. However, many methods for estimating density are too costly or difficult to implement over large spatial and temporal extents. Recently developed spatial mark‐resight (SMR) models are increasingly being applied as a cost‐effective method to estimate density when data...
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Context Predation-risk and ecological disturbance regimes can both influence behavioral decisions by prey, yet few studies have simultaneously considered responses to these ecological pressures. Elucidating relationships between predation risk and the costs and benefits associated with multiple natural disturbances can contribute to a better unders...
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Studies of animal abundance and distribution are often conducted independently of research on movement, despite the important links between processes. Movement can cause rapid changes in spatial variation in density, and movement influences detection probability and hence estimates of abundance from inferential methods such as spatial capture‐recap...
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Bait is often used to increase wildlife harvest susceptibility, enhance viewing opportunities, and survey wildlife populations. The effects of baiting depend on how bait influences space use and resource selection at multiple spatial scales. Although telemetry studies allow for inferences about resource selection within home ranges (third-order sel...
Article
On the wintering grounds, wetland selection by waterfowl is influenced by spatiotemporal resource distribution. The ring-necked duck (Aythya collaris) winters in the southeastern United States where a disproportionate amount of Atlantic Flyway ring-necked duck harvest occurs. We quantified female ring-necked duck selection for wetland characteristi...
Article
Ecologists and conservation biologists increasingly rely on spatial capture‐recapture (SCR) and movement modeling to study animal populations. Historically, SCR has focused on population‐level processes (e.g., vital rates, abundance, density, and distribution), while animal movement modeling has focused on the behavior of individuals (e.g., activit...
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Recovery of grassland birds in agricultural landscapes is a global imperative. Agricultural landscapes are complex, and the value of resource patches may vary substantially among species. The spatial extent at which landscape features affect populations (i.e., scale of effect) may also differ among species. There is a need for regional‐scale conser...
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The northern bobwhite (Colinus virginianus) is an ecologically and economically valuable species in the United States. Managers rely on autumn density estimates to set harvest regulations, balancing the interests of hunters and long‐term bobwhite population viability. Spatial capture‐recapture (SCR) is a useful framework for estimating population s...
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Purpose of Review We review recent methodological advancements in estimation of distance-dependent landscape effects on terrestrial species. These methods address key theoretical elements from landscape and metapopulation ecology that were ignored in previous approaches. Models that treat landscapes as circles within which all land features are equ...
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Here we provide guidance for the application of a land sparing production system designed to conserve forest-dependent wildlife in coffee growing regions where environmental conditions preclude coffee cultivation with a land-sharing strategy. In an Integrated Open Canopy (“IOC”) coffee system, shade trees planted with coffee may be eliminated at th...
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Nearctic‐Neotropical migratory birds are considered priority species for conservation because they are subject to threats at distinct breeding, migratory and stopover locations throughout their annual cycle, and many species have undergone severe population declines. Research during the non‐breeding season has focused on identifying the locations a...
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1. Spatial capture-recapture (SCR) models have increasingly been used as a basis for combining capture-recapture data types with variable levels of individual identity information to estimate population density and other demographic parameters. Recent examples are the unmarked SCR (or spatial count model), where no individual identities are availab...
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Understanding how climate change impacts trailing-edge populations requires information about how abiotic and biotic factors limit their distributions. Theory indicates that socially mediated Allee effects can limit species distributions by suppressing growth rates of peripheral populations when social information is scarce. The goal of our researc...
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Science-based management strategies are needed to halt or reverse the global decline of amphibians. In many cases, sound management requires reliable models built using monitoring data. Historically, monitoring and statistical modeling efforts have focused on estimating occupancy using detection–nondetection data. Spatial occupancy models are usefu...
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Climate change is causing the ranges of many species to shift poleward and to higher elevations. Trailing-edge populations near the low-latitude edge of a shifting range are predicted to be at high risk of climate-induced extinction, but conservation efforts are hindered by a lack of information about the global distribution of trailing-edge popula...
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The Central Georgia Bear Population (CGP) is the least abundant and most isolated of Georgia's 3 American black bear (Ursus americanus) populations. Beginning in 2011, changes to regulations governing harvest of the CGP resulted in an increase in female bear harvest, creating concern that future harvest could be an important influence on population...
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Extreme climatic events (ECEs) are increasing in frequency and intensity and this necessitates understanding their influence on organisms. Animal behaviour may mitigate the effects of ECEs, but field studies are rare because ECEs are infrequent and unpredictable. Hurricane Irma made landfall in southwestern Florida where we were monitoring white-ta...
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Conservation of at‐risk species is aided by reliable forecasts of the consequences of environmental change and management actions on population viability. Forecasts from conventional population viability analysis (PVA) are made using a two‐step procedure in which parameters are estimated, or elicited from expert opinion, and then plugged into a sto...
Data
Corrigendum to "Generalized spatial mark–resight models with incomplete identification: An application to red fox density estimates"
Article
Despite advances in tracking technologies, migration strategies remain poorly studied for many small-bodied passerines. Understanding variation within a migration strategy is important as variation impacts a population’s resilience to environmental change. Timing, pathway, and stopovers vary based on intrinsic and extrinsic factors that impact indi...
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Recently introduced unmarked spatial capture–recapture (SCR), spatial mark–resight (SMR), and 2‐flank spatial partial identity models (SPIMs) extend the domain of SCR to populations or observation systems that do not always allow for individual identity to be determined with certainty. For example, some species do not have natural marks that can re...
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• The estimation of abundance of wildlife populations is an essential part of ecological research and monitoring. Spatially explicit capture–recapture (SCR) models are widely used for abundance and density estimation, frequently through individual identification of target species using camera‐trap sampling. • Generalized spatial mark–resight (Gen‐S...
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• Fear of predators can behaviorally mediate prey population dynamics, particularly when predation risk influences reproductive investment. However, the costs of reproductive investment may mitigate predation risk aversion relative to periods when the link between reproductive output and prey behavior is weaker. • We posit that intensity of reprodu...
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The Canada warbler (Cardellina canadensis) is a migratory neotropical warbler species of conservation concern. The 16,807 bp genome was sequenced and contains a 1224 bp control region, 37 genes, and has a nucleotide composition of 30.6% A, 23.7% T, 14.1% G, and 31.6% C. We constructed a phylogenetic tree of species in the order Passeriformes, which...
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Understanding and quantifying demographic parameters that influence population growth is necessary to effectively maintain population persistence in the presence of recent changes in climate and land use. We used a combination of capture–recapture and harvest information from a 42 yr dataset to create an integrated population model that estimates p...
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ContextCommon species important for ecosystem restoration stand to lose as much genetic diversity from anthropogenic habitat fragmentation and climate change as rare species, but are rarely studied. Salt marshes, valuable ecosystems in widespread decline due to human development, are dominated by the foundational plant species black needlerush (Jun...
Article
The winter range of the Bicknell's Thrush (Catharus bicknelli), a globally vulnerable Nearctic-Neotropical migratory songbird, is restricted to the Greater Antilles. Most birds occur on Hispaniola, where the species exhibits sexual habitat segregation, and where the loss of its preferred wet broadleaf habitats has been severe. Conservation of femal...
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1.Understanding the factors influencing recruitment in animal populations is an important objective of many research and conservation programs. However, eval‐uating hypotheses is challenging because recruitment is the outcome of birth and survival processes that are difficult to directly observe. Capture‐recapture is the most general framework for...
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Efforts to understand population dynamics and identify high-quality habitat require information about spatial variation in demographic parameters. However, estimating demographic parameters typically requires labor-intensive capture-recapture methods that are difficult to implement over large spatial extents. Spatially explicit integrated populatio...
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The effects of predicted declines and potential loss of individual populations on species-level genetic diversity is unclear. A number of taxa, including the Canada Warbler (Cardellina canadensis), share wide-ranging geographic distributions in North American boreal forests with trailing-edge populations extending into the southern Appalachian Moun...
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Animal migration has been the subject of intensive research for more than a century, but most research has focused on long‐distance rather than short‐distance migration. Altitudinal migration is a form of short‐distance migration in which individuals perform seasonal elevational movements. Despite its geographic and taxonomic ubiquity, there is rel...
Preprint
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1.Private lands contain much of the world's biodiversity. Conservation of private land, especially agricultural land, is urgent yet challenging because of the diverse priorities of landowners. Local effects of farmland conservation programmes have been evaluated thoroughly, but population-level response to these programmes may depend on effects tha...
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Metapopulation ecology and landscape ecology aim to understand how spatial structure influences ecological processes, yet these disciplines address the problem using fundamentally different modeling approaches. Metapopulation models describe how the spatial distribution of patches affects colonization and extinction, but often do not account for th...
Preprint
Full-text available
Recently introduced unmarked spatial capture-recapture (SCR), spatial mark-resight (SMR), and 2-flank spatial partial identity models (SPIM) extend the domain of SCR to populations or observation systems that do not always allow for individual identity to be determined with certainty. For example, some species do not have natural marks that can rel...
Article
Fire influences the distributions of cover and food resources for ungulates in frequently burned systems. Fire typically improves forage quality, and as a result, herbivores are often drawn to recently burned areas–a response termed the ‘magnet effect.’ Thus, fire can be an important tool for manipulating vegetation to benefit wildlife. However, mo...
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Monitoring vulnerable species is critical for their conservation. Thresholds or tipping points are commonly used to indicate when populations become vulnerable to extinction and to trigger changes in conservation actions. However, quantitative methods to determine such thresholds have not been well explored. The Louisiana black bear (Ursus american...
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Full-text available
1. Private lands contain much of the world's biodiversity. Conservation of private land, especially agricultural land, is urgent yet challenging because of the diverse priorities of landowners. Local effects of farmland conservation programmes have been evaluated thoroughly, but population-level response to these programmes may depend on effects th...
Article
Full-text available
The high cost associated with capture-recapture studies presents a major challenge when monitoring and managing wildlife populations. Recently developed spatial mark-resight (SMR) models were proposed as a cost-effective alternative because they only require a single marking event. However, existing SMR models ignore the marking process and make th...
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Global amphibian declines have been attributed to a number of factors including disease, invasive species, habitat degradation, and climate change. Reintroduction is one management action that is commonly used with the goal of recovering imperiled species. The success of reintroductions varies widely, and evaluating their efficacy requires estimate...
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Context Spatial variation in abundance is influenced by local- and landscape-level environmental variables, but modeling landscape effects is challenging because the spatial scales of the relationships are unknown. Current approaches involve buffering survey locations with polygons of various sizes and using model selection to identify the best sca...
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The Louisiana black bear (Ursus americanus luteolus) was reduced to a few small, fragmented, and isolated subpopulations in the Lower Mississippi Alluvial Valley by the mid-twentieth century resulting from loss and fragmentation of habitat. In 1992, the United States Fish and Wildlife Service (USFWS) granted the Louisiana black bear threatened stat...
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Gopher tortoise (Gopherus polyphemus) populations are declining range-wide primarily because of habitat loss, fragmentation, and degradation, but low recruitment due to nest predation also may be contributing to this decline. The relationship of nest location and nest survival is unknown. Therefore, our objective was to determine whether nest locat...
Article
Red imported fire ants (Solenopsis invicta; fire ants) are predators of turtle (Testudine) eggs and hatchlings, but little information is available indicating how and when fire ants detect turtle nests during incubation. Therefore, during 2014, we compared fire ant presence at gopher tortoise (Gopherus polyphemus) nests in burrow aprons in early an...
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Little is known about common bottlenose dolphin (Tursiops truncatus) seasonal migration along the United States southeastern Atlantic coast, or what factors influence migratory patterns. Therefore, our objectives were to: 1) document evidence for seasonal movement of dolphins in this region (that would indicate migratory behavior) and 2) determine...
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Invasive species, such as the Red Imported Fire Ant (Solenopsis invicta, hereafter, Fire Ant), impact native species via predation, competition for resources, and modifying prey behavior. However, relatively little is known about the effects of Fire Ants on oviparous reptiles. Therefore, we quantified nestling and hatchling survival and examined in...
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Models of population dynamics are frequently used for purposes such as testing hypotheses about density dependence and predicting species' responses to future environmental change or conservation actions. Fitting models of population dynamics to field data is challenging because most data sets are characterized by observation error, which can infla...
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1.The reintroduction of a species into its historic range is a critical component of conservation programmes designed to restore extirpated metapopulations. However, many reintroduction efforts fail, and the lack of rigorous monitoring programmes and statistical models have prevented a general understanding of the factors affecting metapopulation v...