Biology subjects

Alston, J. M.

Publications and source records attributed to Alston, J. M..

14 recordsLinked to original sources

bioRxiv2026

Crop raiding as an emerging threat to giraffes: drivers and perceived effectiveness of countermeasures

Giraffes, unlike other large mammals, typically pose minimal risk to humans, their animals, and crops, so they are traditionally not involved in human-wildlife conflict. Tree crops, however, are expanding across Africa, resulting in crop raiding by giraffes and retaliatory snaring, poaching, and killing of giraffes in response. The dynamics of giraffe crop raiding, however, are poorly understood, making effective interventions difficult to implement. To better understand key factors for humans and giraffes that mediate crop raiding, we used a multi-method approach to estimate giraffe abundance and activity, understand farmers perceptions and decisions, and test countermeasures around Garissa Giraffe Sanctuary in eastern Kenya. We hypothesized that 1) giraffe farm invasion would occur in dry seasons, 2) farms growing mangoes would be more likely to be invaded, 3) reducing invasion with only physical barriers would be less effective than adding behavior-based countermeasures, 4) perceptions would match giraffe activity and 5) countermeasure adoption would be driven by cost. We found that invasion and crop raiding primarily occur during the dry season and are associated with mangoes. Farmers are using many countermeasures. Effective countermeasures target giraffe behavior combined with physical barriers. Countermeasures are most effective when negative associations with humans are reinforced. Floodlights and speakers that play predator calls both reduce invasion, but only if used consistently. Overall, farmers perceptions matched giraffe dynamics. Availability was the most important factor in farmers willingness to try a countermeasure. Our results suggest that conflict can be reduced and there is interest from farmers in doing so, but use of countermeasures should be consistently applied and supported by making necessary equipment and instructions available.

ecology↗

bioRxiv2026

A holistic survey of small mammal diversity across an iconic Madrean Sky Island (Santa Catalina Mountains, Arizona, USA)

The Santa Catalina Mountains are an iconic member of the Madrean Sky Islands, rising above Tucson, Arizona, USA, where the Catalina Highway connects Sonoran desertscrub to stands of conifer forest nearly 2,800 meters in elevation. As one of the [~]54 forested mountain areas in this system, the Santa Catalinas host unique biotic communities relative to the surrounding lowlands. However, most of these sky islands lack the surveys of resident small mammals (either historical or recent) needed for studying biodiversity in the context of changing climate and habitat use. From 2021 to 2023, we surveyed 10 localities on the north and south slopes of the Santa Catalina Mountains using holistic sampling methods to document terrestrial small mammal diversity and preserve multiple tissue types. Here we summarize these new collections relative to previous voucher specimens and human observations, identifying gaps for future work to address. Our survey recorded the presence of 15 species, preserved 150 voucher specimens paired with a suite of flash-frozen tissues, and non-lethally sampled another 219 individuals (ear tissue, feces, ectoparasites, and measurements) to provide populational data from sites where vouchering occurred. Despite the road accessibility and long history of sampling in the Santa Catalina Mountains, our surveys extended the known elevational range for 8 species, including the first known specimen of Reithrodontomys fulvescens from the area. Our use of a transect-based survey design, which maximizes species diversity across biotic communities, paired with holistic specimen preservation techniques, provides a model for surveying patterns of population genetic and parasite sharing relationships across other Madrean Sky Islands, bridging a [~]40 year lull in specimen preservation while adding new data dimensions that promote integrative studies of small mammal biodiversity. With more complete sampling, other mountains will offer promising replicates for studying eco-evolutionary impacts of the regions episodic habitat connectivity. Teaser textSurveying the terrestrial small mammals of the Santa Catalina Mountains, part of the Madrean Sky Islands, we analyze modern occurrences relative to previous records and demonstrate the potential value of holistically surveying sky island small mammals.

zoology↗

bioRxiv2026

Patchy distribution of a Madrean Sky Island squirrel shaped by historical habitat configuration

Sky islands, mountain-top forests isolated by surrounding lowlands, offer unique opportunities to test how past and present landscapes shape species distributions. We examined the distribution of the Arizona gray squirrel (Sciurus arizonensis) across the Madrean Archipelago to test the constraint-based dynamic island biogeography (C-DIB) model, which posits that current occupancy in the sky islands reflects historical habitat size and connectivity. Using verified specimen records, we modeled climatically suitable habitats across four time periods: the Last Glacial Maximum (LGM), Mid-Holocene (MH), Present, and Future. For each mountain, we quantified suitable habitat area and estimated least-cost dispersal distances to assess both persistence and colonization potential. Our results suggest that species presence is best explained by LGM habitat metrics, which marginally outperformed models based on current conditions. Mountains that were large or well-connected during the LGM continue to support S. arizonensis, whereas historically isolated ranges remain unoccupied despite suitable contemporary habitat. These findings indicate a legacy of Pleistocene connectivity and reveal patterns of distributional disequilibrium. Furthermore, climatically suitable habitat for S. arizonensis has shifted both elevationally and geographically through time, reflecting long-term responses to climatic change. Together, these results emphasize the importance of protecting historically connected refugia, restoring riparian corridors that facilitate dispersal, and developing mountain range-specific management strategies that account for elevational shifts and potential downslope habitat recovery under future climate scenarios.

ecology↗

bioRxiv2026

Using bobcat (Lynx rufus) movement patterns to inform strategies for road mitigation

O_LIEven for wildlife species that often persist in urban and suburban areas, vehicle collisions remain a common source of mortality, and roads can fragment and degrade habitat. Quantifying animal behavior near roads can help wildlife managers develop management strategies to reduce mortality from vehicles while maintaining connectivity. C_LIO_LITo determine how roads affect movement of bobcats (Lynx rufus)--a common mesopredator in urban and suburban areas of North America--we analyzed GPS tracking data from bobcats using continuous-time movement analyses. Our study focused on three questions regarding bobcat movement near roads: (1) Are roads barriers to bobcat movement? (2) How often do bobcats use wildlife crossing structures to cross roads? (3) How does bobcat movement behavior change when bobcats are closer to roads? C_LIO_LIWe found that bobcats crossed roads 11% less frequently than expected from random chance, and this effect was largely driven by interstates and major local roads. We found little evidence that bobcats selectively used culverts or underpasses to cross roads, or that bobcat movement behavior (i.e., speed or home range size) varied with road density, although daily distance traveled increased with road density. C_LIO_LISynthesis and applications: Managers attempting to reduce bobcat mortality from vehicle collisions must do more than simply building wildlife crossing structures. Fences to funnel bobcats toward crossing structures, rumble strips to scare bobcats from roads, reduced speed limits, and wildlife warning signs for drivers may be more effective tools for reducing bobcat-vehicle collisions. This study also provides a rigorous framework for considering the implications of movement behavior for lack of connectivity and mortality as distinct but not mutually exclusive threats posed by roads for wildlife. C_LI

animal behavior and cognition↗

bioRxiv2025

Human shields alter antipredator behavior in Guenther's dik-dik (Madoqua guentheri)

Human activities affect landscape use by wildlife, with many predators actively avoiding areas near humans. In human-occupied areas, prolonged habituation to human activity could therefore lead to relaxed antipredator behavior by prey species, which can be detrimental when predators return or if individuals are translocated to new areas that host predators. We conducted behavioral trials to test whether exposure of Guenthers dik-dik (Madoqua guentheri) to human activity affected habituation to humans and, by extension, response to predation cues. We hypothesized that dik-diks living in areas with higher levels of human activity would exhibit shorter flight initiation distances and spend less time responding to predation cues than those in areas with less human activity, but would respond more strongly to non-specific predation cues (i.e., alarm calls from white-browed sparrow-weavers, a locally common bird) than to cues associated with predators that avoid human activity (i.e., hyena vocalizations). Flight initiation distance and responses to both sparrow-weaver alarm calls and hyena vocalizations varied predictably with differences in human activity: dik-diks living in areas with more human activity had shorter flight initiation distances and spent less time responding to predation cues than those living in areas with less human activity, but responded more strongly to the sparrow-weaver alarm calls than hyena vocalizations in the area with the highest level of human activity. As human populations expand and overlap increasingly with predators, human settlements and activities may increase susceptibility of prey to predators by increasing prey naivety to predators that avoid humans. These results are particularly relevant for ecotourism in working landscapes and translocation of habituated animals, both of which may increase prey naivety.

animal behavior and cognition↗

bioRxiv2025

How many mammal species are there now? Updates and trends in taxonomic, nomenclatural, and geographic knowledge.

The Mammal Diversity Database (MDD) is an open-access resource providing up-to-date taxonomic, nomenclatural, and geographic data for global mammal species. Since its launch in 2018, the MDD has transformed the traditionally static process of updating mammalian taxonomy into regular online releases reflecting the latest published research. To build on this foundation, we here present version 2.0 of the MDD (MDD2), which catalogues 6,759 living and recently extinct mammal species, representing net increases of 4.1% and 24.8% over MDD version 1.0 and Mammal Species of the World, 3rd edition (MSW3), respectively. Additionally, we identify a net increase of 68.8% (+2,754; 3,149 splits + de novo, 395 lumps) species since 1980 at a rate of [~]65 species/year based on past totals from 14 mammalian compendia, leading to projections of [~]7,084 species by 2030 and [~]8,382 by 2050 if these trends continue. Key updates in MDD2 include: (i) codings of US state, country, continent, and biogeographic realm geographic categories for each species; (ii) a comprehensive nomenclatural dataset for 50,230 valid and synonymous species-rank names, curated with type locality and specimen information for the first time; and (iii) integration between the MDD and the databases Hesperomys and Batnames for greater data accuracy and completeness. These updates bridge critical gaps in the taxonomic and nomenclatural information needed for ongoing revisions and assessments of mammalian species diversity. Using these data, we evaluate temporal and geographic trends over the past 267 years, identifying four major time periods of change in mammalian taxonomy and nomenclature: (i) the initial monographic description of traditionally charismatic species (1758-1880); (ii) the peak of descriptive taxonomy, describing subspecies, and publishing in journals (1881-1939); (iii) the shift toward revisionary taxonomy and polytypic species (1940- 1999); and (iv) the current technology-driven period of integrative revisionary taxonomy (2000- present). Geographically, new species recognition since MSW3 has been concentrated in equatorial, mountainous, and island regions, highlighting areas of high mammal endemism (e.g., Madagascar, Philippines, Andes, East Africa, Himalayas, Atlantic Forests). However, gaps in 21st century taxonomic activity are identified in West and Central Africa, India, and some parts of Indonesia. Currently lagging conservation assessments are alarming, with 25% of the MDD2-recognized mammal species allocated to the understudied conservation threat categories of Data Deficient (11%) or Not Evaluated (14%), underscoring the need for greater taxonomic integration with conservation organizations. Governance advancements in MDD2 include the establishment of external taxonomic subcommittees to guide data collection and curation, a rewritten website that improves access and scalability, a cross-platform application that provides offline access, and new partnerships to continue linking MDD data to global biodiversity infrastructure. By providing up-to-date mammalian taxonomic and nomenclatural data--including links to the text of original name descriptions, type localities, and type specimen collections--the MDD provides an integrative resource for mammalogists and conservationists to more easily track the status of their study organisms. Teaser Text: The Mammal Diversity Database 2.0, listing 6,759 mammal species and 50,230 species-level synonyms, unifies 267 years of taxonomic, nomenclatural, and geographic data to track global mammal biodiversity and provide a continually updated resource for the mammalogical community. Teaser Image: Figure 3. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/640393v1_fig3.gif" ALT="Figure 3"> View larger version (34K): org.highwire.dtl.DTLVardef@1012e67org.highwire.dtl.DTLVardef@8d99d7org.highwire.dtl.DTLVardef@6f21b9org.highwire.dtl.DTLVardef@f23fd_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 3.C_FLOATNO Type locality locations for species-rank mammal taxa described from 1 January 2000 to 15 August 2024. Map gray-scale country coloration represents the total number of currently valid species type localities found per country described within this period. Colored dots represent the exact georeferenced type locality of all currently valid species (red circles) and names currently considered synonyms and subspecies (blue diamonds) in MDD2. Most coordinates were generated from the original description of each name when included directly in publication, while others were georeferenced using GeoLocate or WikiMedia GeoHack place coordinates when not included in the original description publication. The georeferenced localities were mapped and both programmatically and visually vetted for accuracy. Latitude and longitude in decimal degrees is included for each of the names mapped here in the MDD2 synonym list, Supplementary Data SD2. C_FIG

zoology↗

bioRxiv2025

Impacts of climate change on the movement ecology of an imperfect homeotherm

Rapid, human-induced climate change has posed significant challenges to wildlife. One key strategy animals use to cope with environmental temperature fluctuations is behavioral thermoregulation. Understanding how climate change is expected to influence animal behavior is crucial for assessing its impact on species survival and informing effective conservation efforts. Giant anteaters have been found to exhibit conspicuous behavioral responses to temperature changes. Despite their broad thermal neutral zone (15 - 36{degrees}C), climate projections indicate that this vulnerable mammal is increasingly likely to experience heat stress. We used GPS tracking and continuous-time analyses to investigate how environmental temperature influences the movement ecology of giant anteaters. We integrated our findings with climate change projections to link giant anteaters responses to present weather conditions with those expected under future climate scenarios. Giant anteaters movement speed exhibited a negative quadratic response to temperature, peaking at 23.7{degrees}C. 95% of their movement occurred between 15.0 - 32.3{degrees}C, which aligns with their thermal neutral zone. The increasing temperature led giant anteaters to increase selection for native forests, but had no effect on selection for exotic tree plantations. This shows the importance of native forests as these thermal shelters help to mitigate the negative consequences of high temperatures on anteaters movement. However, the warmer temperatures predicted for Brazil throughout the rest of the 21st century indicate that giant anteaters may experience a reduction of up to 84% in their movement speed. This would hinder the acquisition of sufficient energy resources and threaten the species persistence. We emphasize the need for conservation efforts that account for the impacts of climate change on species survival and stress the importance of preserving forests as essential refuges that help wildlife to cope with rising temperatures.

ecology↗

bioRxiv2024

Home range spillover in habitats with impassable boundaries: Causes, biases, and corrections using autocorrelated kernel density estimation

O_LIAn animals home range plays a fundamental role in determining its resource use and overlap with conspecifics, competitors and predators, and is therefore a common focus of movement ecology studies. Autocorrelated kernel density estimation addresses many of the shortcomings of traditional home range estimators when animal tracking data is autocorrelated, but other challenges in home range estimation remain. C_LIO_LIOne such issue is known as spillover bias, in which home range estimates do not respect impassable movement boundaries (e.g., shorelines, fences), and occurs in all forms of kernel density estimation. While several approaches to addressing spillover bias are used when estimating home ranges, these approaches introduce bias throughout the remaining home range area, depending on the amount of spillover removed, or are otherwise inaccessible to most ecologists. Here, we introduce local corrections to home range kernels to mitigate spillover bias in (autocorrelated) kernel density estimation in the continuous time movement model (ctmm) package, and demonstrate their performance using simulations with known home range extents and distributions, and a real world case study. C_LIO_LISimulation results showed that local corrections minimised bias in bounded home range area estimates, and resulted in more accurate distributions when compared to commonly used post-hoc corrections, particularly at small-intermediate sample sizes. C_LIO_LIComparison of the impacts of local vs post-hoc corrections to bounded home ranges estimated from lake trout (Salvelinus namaycush) demonstrated that local corrections constrained bias within the remaining home range area, resulting in proportionally smaller home range areas compared to when post-hoc corrections are used. C_LI

ecology↗

bioRxiv2023

Symbiotic acacia ants drive nesting behavior by birds in an African savanna

Mutualisms between plants and ants are common features of tropical ecosystems around the globe and can have cascading effects on interactions with the ecological communities in which they occur. In an African savanna, we assessed whether acacia ants influence nest site selection by tree-nesting birds. Birds selected nest sites in trees inhabited by ant species that vigorously defend against browsing mammals. Future research could address the extent to which hatching and fledging rates depend on the species of ant symbiont, and why ants tolerate nesting birds but not other tree associates (especially insects).

ecology↗

bioRxiv2022

Clarifying space use concepts in ecology: range vs. occurrence distributions

Quantifying animal movements is necessary for answering a wide array of research questions in ecology and conservation biology. Consequently, ecologists have made considerable efforts to identify the best way to estimate an animals home range, and many methods of estimating home ranges have arisen over the past half century. Most of these methods fall into two distinct categories of estimators that have only recently been described in statistical detail: those that measure range distributions (methods such as Kernel Density Estimation that quantify the long-run behavior of a movement process that features restricted space use) and those that measure occurrence distributions (methods such as Brownian Bridge Movement Models and the Correlated Random Walk Library that quantify uncertainty in an animal movement path during a specific period of observation). In this paper, we use theory, simulations, and empirical analysis to demonstrate the importance of applying these two classes of space use estimators appropriately and distinctly. Conflating range and occurrence distributions can have serious consequences for ecological inference and conservation practice. For example, in most situations, home-range estimates quantified using occurrence estimators are too small, and this problem is exacerbated by ongoing improvements in tracking technology that enable more frequent and more accurate data on animal movements. We encourage researchers to use range estimators to estimate the area of home ranges and occurrence estimators to answer other questions in movement ecology, such as when and where an animal crosses a linear feature, visits a location of interest, or interacts with other animals. Open Research StatementTracking data on Aepyceros melampus, Beatragus hunteri, Bycanistes bucinator, Cerdocyon thous, Eulemur rufifrons, Glyptemys insculpta, Gyps coprotheres, Madoqua guentheri, Ovis canadensis, Propithecus verreauxi, Sus scrofa, and Ursus arctos are publicly archived in the Dryad repository (Noonan et al. 2018; https://doi.org/10.5061/dryad.v5051j2), as are data from Procapra gutturosa (Fleming et al. 2014a; https://doi.org/10.5061/dryad.45157). Data on Panthera onca were taken from (Morato et al. 2018). Additional data are publicly archived in the Movebank repository under the following identifiers: Canis latrans, 8159699; Canis lupus, 8159399; Chrysocyon brachyurus, 18156143; Felis silvestris, 40386102; Gyps africanus, 2919708; Lepus europaeus, 25727477; Martes pennanti, 2964494; Panthera leo, 220229; Papio cynocephalus, 222027; Syncerus caffer, 1764627; Tapirus terrestris, 443607536; Torgos tracheliotus, 2919708; and Ursus americanus, 8170674.

ecology↗

bioRxiv2022

Mitigating pseudoreplication and bias in resource selection functions with autocorrelation-informed weighting

O_LIResource selection functions are among the most commonly used statistical tools in both basic and applied animal ecology. They are typically parameterized using animal tracking data, and advances in animal tracking technology have led to increasing levels of autocorrelation between locations in such data sets. Because resource selection functions assume that data are independent and identically distributed, such autocorrelation can cause misleadingly narrow confidence intervals and biased parameter estimates. C_LIO_LIData thinning, generalized estimating equations, and step selection functions have been suggested as techniques for mitigating the statistical problems posed by autocorrelation, but these approaches have notable limitations that include statistical inefficiency, unclear or arbitrary targets for adequate levels of statistical independence, constraints in input data, and (in the case of step selection functions) scale-dependent inference. To remedy these problems, we introduce a method for likelihood weighting of animal locations to mitigate the negative consequences of autocorrelation on resource selection functions. C_LIO_LIIn this study, we demonstrate that this method weights each observed location in an animals movement track according to its level of non-independence, expanding confidence intervals and reducing bias that can arise when there are missing data in the movement track. C_LIO_LIEcologists and conservation biologists can use this method to improve the quality of inferences derived from resource selection functions. We also provide a complete, annotated analytical workflow to help new users apply our method to their own animal tracking data using the ctmm R package. C_LI

ecology↗

bioRxiv2021

Environmental drivers of body size in North American bats

Bergmanns Rule--which posits that larger animals live in colder areas--is thought to influence variation in body size within species across space and time, but evidence for this claim is mixed. We tested four competing hypotheses for spatio-temporal variation in body size within bat species during the past two decades across North America. Bayesian hierarchical models revealed that spatial variation in body mass was most strongly (and negatively) correlated with mean annual temperature, supporting the heat conservation hypothesis (historically believed to underlie Bergmanns Rule). Across time, variation in body mass was most strongly (and positively) correlated with net primary productivity, supporting the resource availability hypothesis. Climate change could influence body size in animals through both changes in mean annual temperature and in resource availability. Rapid reductions in body size associated with increasing temperatures have occurred in short-lived, fecund species, but such reductions likely transpire more slowly in longer-lived species.

ecology↗

bioRxiv2021

Temperature-dependent use of daily torpor attenuates the energetic consequences of habitat selection for a widespread bat

Homeothermy requires increased metabolic rates as temperatures decline below the thermoneutral zone, so homeotherms typically select microhabitats within or near their thermoneutral zones during periods of inactivity. However, many mammals and birds are heterotherms that relax internal controls on body temperature when maintaining a high, stable body temperature is energetically costly. Such heterotherms should be less tied to microhabitats near their thermoneutral zones, and because heterotherms spend more time in torpor and expend less energy at colder temperatures, heterotherms may even select microhabitats in which temperatures are well below their thermoneutral zones. We studied how temperature and daily torpor influence selection of diurnal roosts by a heterothermic bat (Myotis thysanodes). We (1) quantified the relationship between ambient temperature and daily duration of torpor, (2) simulated daily energy expenditure over a range of microhabitat (roost) temperatures, and (3) quantified the influence of roost temperature on roost selection. While warm roosts substantially reduced energy expenditure of simulated homeothermic bats, heterothermic bats modulated their use of torpor to maintain a constant level of energy expenditure over the course of a day. Daily torpor expanded the range of energetically economical microhabitats, such that roost selection was independent of roost temperature. Our work adds to a growing literature documenting functions of torpor beyond its historical conceptualization as a last-resort measure to save energy during extended or acute energetic stress.

ecology↗

bioRxiv2019

Temperature shapes movement and habitat selection by a heat-sensitive ungulate

ContextWarmer weather caused by climate change poses increasingly serious threats to the persistence of many species, but animals can modify behavior to mitigate at least some of the threats posed by warmer temperatures. Identifying and characterizing how animals modify behavior to avoid the negative consequences of acute heat will be crucial for understanding how animals will respond to warmer temperatures in the future. ObjectivesWe studied the extent to which moose (Alces alces), a species known to be sensitive to heat, mitigates heat on hot summer days via multiple different behaviors: (1) reduced movement, (2) increased visitation to shade, (3) increased visitation to water, or (4) a combination of these behaviors. MethodsWe used GPS telemetry and a step-selection function to analyze movement and habitat selection by moose in northeastern Minnesota, USA. ResultsMoose reduced movement, used areas of the landscape with more shade, and traveled nearer to mixed forests and bogs during periods of heat. Moose used shade far more than water to ameliorate heat, and the most pronounced changes in behavior occurred between 15{degrees}C and 20{degrees}C. ConclusionsResearch characterizing the behaviors animals use to facilitate thermoregulation will aid conservation of heat-sensitive species in a warming world. The modeling framework presented in this study is a promising method for evaluating the influence of temperature on movement and habitat selection.

zoology↗