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Kathryn A. Schoenecker

Publications and source records attributed to Kathryn A. Schoenecker.

At least 19 recordsLinked to original sources
USGS2026

Mountain lion prey-selection in a community comprised of native and introduced ungulate species

Species introductions are a hallmark of human influence on ecosystems worldwide. In communities where native and introduced fauna coexist, predators may select prey based on availability or vulnerability. Free-roaming feral horses ( Equus caballus ) are a recent addition to North America and have become widespread, abundant, and in some areas serve as major prey for mountain lions ( Puma concolor ), a native carnivore. The proliferation of horses as well as potential effects of mountain lion predation on native ungulates create ecological and social management challenges; our goal was to assess mountain lion prey selection in a system composed of native mule deer ( Odocoileus hemionus ) and introduced feral horses. Our objectives were to: (1) describe seasonal patterns of prey use within individual mountain lion home ranges; (2) quantify prey use relative to availability; and (3) determine seasonal kill rates on the two primary ungulates in the study area. Fieldwork occurred in southeastern Nevada, 2021–2022. We identified prey use by investigating cache sites from 6 GPS-collared mountain lions. Prey availability and relative abundance were estimated with 49 camera traps distributed across the 3,158-km² study area. During the growing season, weekly kill rates averaged 0.22 deer and 0.55 horses, and in winter, 1.43 deer and 0.33 horses. Thus, lions killed horses at 2.54 times the rate of deer in the growing season but deer at 4.33 times the rate of horses in winter. Model selection indicated mule deer density and prey age class were the strongest predictors of prey species. Lions selected adult deer over fawns, and foals over adult horses, suggesting choices may be driven by optimal prey size rather than species. Mountain lions prey on foals in areas with relatively high mule deer densities, suggesting deer presence may increase foal vulnerability. We hypothesize that lions select foals when available, potentially reducing pressure on mule deer and/or supporting larger lion populations than would occur without this additional prey source. Although individual-level data on mountain lions are challenging to obtain, such information could help managers identify individuals for removal or conservation, improving predator-management outcomes in mixed-prey systems.

Nevada↗
USGS2026

Growth patterns, sexual dimorphism, and seasonal body mass variation in Plains Zebra of the Serengeti region, Tanzania

Knowledge of growth patterns and physical properties of animals helps researchers assess population characteristics and health in the field. Information on age-specific body measurements and growth patterns is rare in ungulates because examining a large portion of a population is time-, budget-, and personnel-intensive in the wild. We collected age- and sex-specific body measurements from 442 Plains Zebra ( Equus quagga boehmi ) culled in the Serengeti region, Tanzania, between 1969 and 1971. The dataset contained 307 males and 133 females. We found that males were on average 2.8% larger than females in body measurements of heart girth, height at shoulder, neck-body length, hind foot length, and the body mass, indicating minimal sexual dimorphism in adult Plains Zebra. We used polynomial regression to explore the relationship between heart girth and body mass and applied third-degree polynomial regression models to predict body mass for 34 females and 115 males with recorded girth but missing body mass records. We applied 5 non-linear models—Gompertz, von Bertalanffy, Bertalanffy-Pütter, logistic, and Richards—to characterize sex-specific growth trajectories for each trait. Our results showed that different traits followed different growth patterns, with size asymptotes reached by ∼2 to 5 yr depending on trait and sex. Seasonal trends in adult body mass were also evaluated using generalized linear models incorporating sex and cyclical effects of day of year. While female body mass showed little seasonal variation, adult males exhibited a 16.9% increase in mass during the wet season, followed by a sharp decline, suggesting greater seasonal plasticity and energetic investment. Our work is one of the few studies on body size and growth in wild equids, which provides new information on age- and sex-specific growth trajectories for comparison across zebra subspecies over time and space.

Serengeti region↗
USGS2026

When the desert dries: Rainfall drives conflicts and conservation challenges for onager (Equus hemionus onager)

Increasingly, the conservation of large and wide-ranging animals is challenged by environmental variability, static boundaries of protected areas, and the expansion of human activities. The Critically Endangered Onager ( Equus hemionus onager ) exemplifies these issues in Qatrouiyeh National Park (QNP) and the surrounding Bahram-e-Goor Protected Area (BPA) in Iran. Using GPS telemetry data from 9 adult females tracked over 2 years, we examined seasonal patterns in movement and incursions into cultivated lands in 2017 and 2018. Net squared displacement analyses indicated that most individuals exhibited range-resident behavior with occasional nomadic movements, with no evidence for migration (i.e., predictable movements to and from distinct seasonal ranges). Both monthly home range size and monthly movement rate varied seasonally, peaking in late spring and early summer (May–July). Individual home ranges were between 257 and 1,928 km 2 , while the extrapolated population-level home range (718 km 2 ; 95% confidence interval = 276–1368) extended well outside QNP, covering large portions of the BPA. Occurrence distributions also expanded beyond the protected area into adjacent cultivated lands, highlighting the use of human-occupied areas by onagers. We recorded 2,285 (out of 72,168) GPS locations within cultivated lands and their surrounding 50 m buffer, with 60% of these incursions occurring immediately adjacent to QNP. Most incursions occurred at night and were strongly associated with both season and cumulative rainfall over the preceding 9 months. These findings emphasize how rainfall-driven variability in resource dynamics shapes the spatial distribution and behavior of onagers, thus elevating the risk of conflict with humans. The scale and seasonality of Onager movements highlight the need for flexible, landscape-level conservation strategies that extend beyond fixed park boundaries to encompass critical habitats and to mitigate conflict across the broader region.

Bahram-e-Goor Protected Area, Qatrouiyeh National ↗
USGS2026

Movement ecology and disease exposure in free-roaming donkeys in California, USA

Feral donkeys ( Equus asinus ) are well adapted to arid ecosystems and are found in large populations in the deserts of Australia and the Americas. We assessed resource selection and seasonal home range size of female donkeys in southern California between 2020 and 2022 based on telemetry data. We also examined whether dyads with greater encounter rates were more likely to test positive for asinine herpesvirus 5 (AHV-5) and/or Streptococcus equi zooepidemicus (SEZ). Donkey home ranges were non-significantly larger in the cool/wet season (November through March; mean 318.37 ± sd 417.65 km 2 ) than in the hot/dry season (April through October; mean 159.35 ± 212.43 km 2 ). Donkeys selected flatter areas closer to water year-round but selected greater herbaceous cover during the cool/wet season and lower heat loads during the hot/dry season. Individuals testing positive for SEZ selected lower elevations during the wet season and closer distances to water during the dry season; donkeys testing positive for AHV-5 selected areas farther from water during the wet season and steeper slopes during the dry season. The dyad encounter rate was unrelated to presence of either disease. Our results contribute to the understanding of donkey ecology, allowing feral populations to be better controlled by specific and focused management.

California↗
USGS2026

Effects of mountain lion predation on reducing feral horse population growth rates: Panacea or pipedream?

A goal of applied ecology is to evaluate how demographic rates contribute to population growth and how demography might be manipulated to achieve management objectives. In western North America, many feral horse ( Equus caballus ) populations occupying public lands are protected by federal law and managed for site-specific numerical targets. However, feral horses can exhibit population growth rates exceeding 20% per yr, which can lead to overpopulation, and therefore conflict with other permitted land uses. In response, some stakeholder groups have advocated for natural solutions to the problem of rapid growth and overabundance. Mountain lion ( Puma concolor ) predation has been hypothesized to have suppressive effects on horse population growth rates under some conditions. Here, we evaluated the degree to which this phenomenon might reduce feral horse growth rates using elasticity analysis, scenario analysis with simulations, and an empirical state-space model for a horse population in southeastern Nevada subject to chronic predation. Age-specific elasticities revealed that annual population growth rates (λ) were more sensitive to perturbations in foal and yearling survival rates than for older age-classes. This finding, in conjunction with empirical measures indicating that foals comprised approximately 60% of horses killed by mountain lions, suggests that predation may have greater potential to reduce horse population growth rates than previously recognized. Scenario analysis predicted that horse populations could decrease to target levels within 10 years if predation reduced: (1) annual foal survival by 80% each year, or (2) annual survival rates of foals, yearlings, and 2-year olds by >60%. The state-space model indicated that the heavily predated Nevada horse population experienced positive population growth during 2022 and 2023 (λ = 1.07, both years). Using information on known predation-caused mortalities from 2020–2021, our model predicted that population growth rate in the absence of predation (‘predicted λ’) would have been approximately twice as high (predicted λ 2020 = 1.14; predicted λ 2021 = 1.14 in 2021). Taken together, our results suggest that predation is unlikely to singularly induce stable or negative population growth of feral horses. That said, our findings suggest two aspects of predation that may benefit resource managers. First, chronic predation may reduce λ, thereby increasing the time required for populations to either recover from declines, or exceed management objectives; and second, predation may be most effective in achieving management objectives for horse populations when combined with other interventions, such as removals or fertility control treatments.

Nevada↗
USGS2026

Captivity may broadly impede bison ecological function: Space, season, and management

American bison ( Bos bison ) were spared from numerical extinction but considered to be ecologically extinct, partially due to spatial restrictions in their former range. A key component of the ecological function of bison is their ability to adjust their spatial behaviors at multiple scales to match the seasonal distributions and availability of resources. To understand how management influences the amount and seasonality of space bison use at various scales, we estimated home range using autocorrelated kernel density estimators (95% utilization distribution) and foraging patch size by the maximum variance in first-passage time at four temporal scales (annual, growing, nongrowing, and focal seasons) for two free-ranging and three captive bison herds. The seasonal differences in space-use within management regimes and study areas were treated as nonparametric related measures while differences amongst management regimes and study areas were treated as nonparametric independent measures. Seasonal variations in space-use were detected in both management regimes, but only free-range bison depicted this pattern at the larger home range scale (p < 0.001). Free-range bison had significantly larger home ranges across seasons compared to captive bison (p < 0.001), but captive bison had larger foraging patch sizes during the growing season than free-range bison. Study areas with captive bison did not differ in their amount of space-use at any scale or season (p > 0.05). The strongest differences were apparent among study herds in annual home range size (p < 0.001) and growing season foraging patch size (p < 0.001). Our results demonstrate that captivity likely prevents bison from using their available landscape seasonally at broad scales, which could have ecological consequences for this historically nomadic herbivore. Although sociopolitical realities prevent bison restoration at a continental scale, increasing the amount of space available to bison where possible has the potential to replicate previous ecological processes. Further research can evaluate the influence of local environmental conditions on seasonality of bison space-use and can assess effects of scale on the ecological impacts of bison.

Colorado, Montana, Texas, Utah↗
USGS2026

Quantifying free-roaming horse body condition: A methodological investigation using game cameras and observer bias corrections

Large populations of free-roaming horses (Equus caballus ) inhabit the western United States, Australia, and other arid and semi-arid rangelands globally. In the United States, horse body condition has been the impetus for gathering and removing horses under an emergency designation and has been noted as a common chronic mortality-causing condition. The Henneke body condition scoring (BCS) system is a qualitative index that includes visual appraisal and physical palpation at multiple anatomical locations on individual horses. This method has been shown to be repeatable between different observers with varying degrees of experience when assessing domestic horses at close proximity. Repeatability using the Henneke BCS system is unknown for free-roaming equids in vast environments, and adequately sampling populations in a minimally biased manner can be logistically challenging. However, estimating body condition using photographs has been shown to be a highly accurate alternative to proximal scoring for multiple scoring systems and species. Our study investigates if an automated, remote camera trap system can be used to estimate free-roaming equid body condition. We compiled existing camera trap data sets from 65 traps into a single data set including more than 3.7 million photos containing images of free-roaming horses from California, Nevada, Utah, and Wyoming. We employed veterinarian-trained animal science students to score horses within randomly sampled, spatially/temporally congruous sequences of animals in our data sets. We compared student scores with veterinarian scores to evaluate whether scorer-specific correction factors are necessary for estimating BCS parameters. Calibration to a fixed reference set reduced between-scorer variance to zero in our population-level BCS estimates. Analysis of our between-scorer variance in our empirical data implies this calibration step can be beneficial when different observers are scoring distinct horse populations across space and/or time.

California, Nevada, Utah, Wyoming↗
USGS2026

Extreme droughts shrink suitable habitats and reduce fitness for large mammals in the American West

Droughts are intensifying across the biosphere, yet the consequences of this phenomenon for wildlife habitat suitability and fitness are poorly studied. We analyzed 12 years of GPS telemetry data for three large mammal species—herbivorous mule deer ( N = 2854), omnivorous black bears ( N = 103), and carnivorous cougars ( N = 105)—to evaluate the effects of drought on each species’ habitat selection across a 500,000-km 2 aridity gradient in the interior West, USA. Additionally, we evaluated interannual variation in mule deer reproduction as a function of drought intensity. Severe drought reduced the area of highly selected habitat by 10.0% for mule deer, 14.3% for black bears, and 18.2% for cougars, suggesting stronger negative effects of drought at upper trophic levels. We also found that mule deer fawn recruitment decreased by >34% under extreme drought conditions. Our findings highlight the critical influence of drought on habitat selection of large mammals and common indices of mule deer fitness. Furthermore, we underscore the need for integrating predictions of climate-driven environmental changes into wildlife conservation planning.

Communications Earth & Environment↗
USGS2026

Human dimensions and mountain sheep

We review components of the human dimension relationship between mountain sheep (bighorn sheep [Ovis canadensis] thinhorn [Ovis dalli]) and mankind. The relationships people hold with nature are incorporated into policymaking, regulation, and funding of wildlife management. Bighorn sheep experienced a massive decline in range and population size during the 19th century due to human occupation of foothills and overgrazing by domestic sheep. This encroachment led to significant habitat loss, unregulated harvesting, and the spread of diseases from domestic sheep to mountain sheep. Efforts to restore populations to their former ranges were influenced by the value of mountain sheep as recreational game species and for wildlife viewing. Restoration brought many bighorn populations into contact with people because the remaining habitat was already subjected to urban expansion. The population declines, fragmentation of habitat, and narrowing of bighorn ranges have had a profound effect on public opinion toward the species, shifting the animal from an accessible source of food through subsistence hunting to a species of conservation concern with limited harvest opportunities. Studies investigating the relationship between humans and mountain sheep have largely focused on the implications of human activities on mountain sheep, including conflict and disturbance, evolutionary pressure from selective hunting, attitudes toward the management of mountain sheep and relevant predator species, and human-wildlife conflict resulting from livestock disease spillover. Human attitudes are understudied. Although strides have been made in restoring mountain sheep populations and their habitats, the species’ population has been reduced compared to historical estimates and its original distribution. As a result, hunting for mountain sheep is often provided as once-in-a-lifetime opportunity. Mountain sheep populations have increased, thanks to partnerships between state and federal governments, and efforts by non-government organizations that provide funding for translocations, research, habitat restoration, disease control, predator management, educational initiatives, and Tribal Nations.

Book chapter↗
USGS2025

Effects of phylogeny and habitat on social structure and behavior of two equid species

Horses ( Equus caballus ) and donkeys ( E. asinus ) are closely related species with different evolutionary histories: their ancestral forms have different social systems related to their adaptations to different ecosystems, exhibiting female defense and resource defense polygyny respectively. We explored any plasticity of response and possible effects of phylogeny and habitat on these species in a feral state, comparing phylogenetic and habitat effects on behavior. We examined two feral horse populations in similar habitat in western Utah, USA, and two feral donkey populations in different habitat types (central Utah Colorado Plateau and central Arizona Sonoran Desert, USA), over 4 years. Species differences were observed: all donkeys spent more time feeding, moving, and lying down than horses, with horses standing more. Donkeys in the Sonoran Desert spent more time feeding and moving, and less time standing and lying down than on the Colorado Plateau. Horses showed less agonistic and affiliative behavior than donkeys. Between species there was no difference in network degree between horses and donkeys, and donkeys had a more saturated network with higher eigenvector centrality but lower clustering coefficient and fewer connected components than horses. Within a species, we found differences between horse populations in network degree, components, and edge density but no difference between donkey populations. Flexibility in how behavior is expressed reflects an interaction between a species’ habitat and their behavioral response to that habitat. Moreover, phylogenetic history seemingly plays a strong role in the behavioral ecology of a species, even after they are domesticated and become feralized.

Arizona, Utah↗
USGS2025

Dynamic riskscapes for prey: Disentangling the impact of human and cougar presence on deer behavior using GPS smartphone locations

Prey species adjust their behavior along human-use gradients by balancing risks from predators and humans. During hunting seasons, prey often exhibit strong antipredator responses to humans but may develop tolerance in suburban areas to exploit human-mediated resources. Additionally, areas with high human activity may offer reduced predation risk if apex predators avoid such locations. This study examined mule deer Odocoileus hemionus behavioral responses to risks from humans and their primary predators, cougars Puma concolor , contextualized by differences in risk levels between study sites, individual risk exposure, and human habituation. We framed our investigation using three non-mutually exclusive hypotheses: (H1) neutral impact, (H2) human shielding (human tolerance driven by cougar avoidance), and (H3) super-additive risk (human avoidance dominating behavior). We controlled for deer phenology and diel period, recognizing that deer behavior varies with these temporal dynamics. Spatiotemporal cougar encounter risk was quantified using GPS collar data, while spatiotemporal human encounter risk and use intensity were quantified using GPS smartphone data. Our results supported H2 and H3, emphasizing the significance of site- and individual-level variation in risk exposure and human use intensity. Deer managed cougar risk adaptively, but humans emerged as the dominant perceived risk, varying by study site. At the site with higher cougar density and lower human hunting pressure, deer exhibited antipredator responses to humans based on individual exposure to human activity, except during hunting season, when tolerance for cougars increased. Conversely, humans were the dominant risk at the site with lower cougar density and greater human hunting pressure. Deer behavior varied significantly across a gradient of human use, influenced by nuanced human presence and predation risks, which were discernible using human smartphone data.

Colorado, Utah↗
USGS2024

Resource availability and heterogeneity affect space use and resource selection of a feral ungulate

Animals adjust their habitat use patterns in response to changes in their physiological needs and environmental conditions. Understanding the mechanisms underlying resource selection and space use across time and space reveals effects of the environment on animals' decisions. We explored the effects of habitat availability and heterogeneity on the seasonal and annual space use and resource selection of two free-roaming feral burro ( Equus asinus ) populations in the United States within distinct climate and habitat conditions: the Sonoran Desert and the Colorado Plateau. As an introduced yet protected species in the United States, understanding burros' interactions with habitat elements is important for their conservation and management, as well as the conservation of sympatric wildlife. We used GPS locations of female burros (72 animals across both study areas) to delineate annual and seasonal ranges and resource selection patterns. We evaluated effects of mean and CV of habitat covariates, including forage, distance to water, and topography, representing availability and heterogeneity of resources, on seasonal and annual range size of burros. Moreover, we explored how burro seasonal and annual resource selection patterns were affected by availability and heterogeneity of resources. In the Sonoran Desert study area, burros had smaller seasonal and annual ranges and constant resource selection patterns across a year, likely due to a freshwater lake in the area, making water a nonlimiting resource. Human presence was the greatest factor affecting range size and resource selection in the Sonoran Desert, where burros selected for areas near roads and human recreation. In the Colorado Plateau study area, where resources were more seasonal, we found larger range sizes and fluctuating resource selection patterns compared to the Sonoran Desert population. Spatial variation in forage, water, and topography significantly affected range size of burros inhabiting the Colorado Plateau study area. Productive habitats with available water support smaller ranges and a more consistent pattern of resource selection. Our results highlight the positive effect of habitat heterogeneity and the negative effect of habitat productivity on range size of animals. Our findings contribute to an improved understanding of habitat requirements for free-roaming burros that currently live under various climate and habitat conditions globally.

Arizona, Utah↗
USGS2024

Evaluating mountain lion diet before and after a removal of feral horses in a semiarid environment

Non-native species can affect ecosystems by influencing native predator-prey dynamics. Therefore, management interventions designed to remove non-natives may inadvertently lead to increased predation on native species. Feral horses are widely distributed throughout the arid parts of western North America. A growing body of research indicates that horses can be an important prey species to mountain lions in ecosystems where they overlap. In December 2020, the Bureau of Land Management removed 455 horses from the Delamar Mountains, Nevada, USA. We leveraged this management intervention to implement a before–after–control–impact study to test hypotheses about predation on horses and native ungulates. We predicted (1) that horses would comprise an important part of the diet in this mixed-prey community, (2) following removal, the proportion of horses in the diet would decrease and native ungulates would increase, and (3) mountain lion home ranges overlapping the treatment areas would increase in response to decreased prey availability. From 2018 to 2022, we investigated 1360 clusters from 29 GPS-collared lions and identified 1056 prey items. To model the probability of a predation event (a kill), we fit a mixed-effects logistic regression model for ungulate prey as a function of lion sex, treatment area (in/out), and treatment period (pre-/post-removal). We used a log-linear regression model to evaluate changes in home range size. The most common prey were mule deer (55%), feral horses (32%), and coyotes (4%). Twenty-two of 29 lions consumed horses, although the rate of horse consumption was highly variable across individuals. Horses of both sexes and all age classes were predated. In contrast to predictions, our models detected no effect of removals on diet composition (β interaction = 0.30 ± 1.1), nor did the removal influence home range size (β interaction = 0.02 ± 0.02). Despite a 46% reduction in horse abundance, we found no evidence for prey-switching following the horse removal treatment. Removal magnitude, rapid horse immigration, and/or behavioral specialization of individual mountain lions may help explain these results. Our findings have important implications for mountain lion and feral horse management in arid environments characterized by high prey diversity, but low prey abundance.

Nevada↗
USGS2024

Using integrated step selection to determine effects of predation risk on bison habitat selection and movement

Animal movement is a fundamental mechanism that shapes communities and ecosystems. Ungulates alter the ecosystems they inhabit and understanding their movements and distribution is critical for linking habitat with population dynamics. Predation risk has been shown to strongly influence ungulate movement patterns, such that ungulates may select habitat where predation risk is lower (refugia), adjust movement rates, temporal patterns, or selection of cover variables in areas with greater predation risk. We evaluated potential predation avoidance behavior in a population of plains bison inhabiting the north rim of Grand Canyon National Park (GRCA) and adjacent Kaibab National Forest (KNF). The KNF has year-round hunting managed by Arizona Game and Fish Department, whereas hunting is not allowed in GRCA. Human-maintained water sources on the KNF are particularly important resources for bison wherein they may be exposed to higher predation risk to access these resources. We used 2-h GPS locations for three years from 31 bison ( n = 9 males; n = 22 females), and integrative step selection analysis to test four hypotheses about the potential for bison to reduce their risk from human predation by avoiding areas of high predation risk; moving faster in areas with high predation risk; entering high-risk areas at night when risk is reduced; and entering high-risk areas in habitats that provide cover (coniferous forest). The highest performing model indicated bison movement was 1.3 times faster per 2-h step interval than in areas with no hunting across all vegetation classes (coniferous forest, shrub, quaking aspen, grass-forb meadow) and across all topography classes (valley, slope, ridge). Bison moved more slowly in grass-forb meadows than all other vegetation types, and in valleys relative to slopes and ridges. Several radio-collared individuals had no GPS locations in KNF for the duration of the study. Bison avoided predation risk using two strategies: moving faster while in the KNF, and fully avoiding high-risk areas by remaining within GRCA. Management that manipulates or reduces timing of hunting seasons may reduce perceived predation risk and encourage bison to distribute into the KNF and across a broader range of available habitat.

Arizona↗
USGS2024

Effects of telemetry collars on two free-roaming feral equid species

There are two species of free-roaming feral equids in North America: horses ( Equus caballus ) and donkeys or “burros” ( E . asinus ). Both species were introduced as domestic animals to North America in the early 1500s and currently inhabit rangelands across the western United States, Canada, and all continents except Antarctica. Despite their global distribution, little is known about their fine scale spatial ecology. Contemporary research tools to assess space use include global positioning system (GPS) tracking collars, but older models were problematic due to stiff collar belting causing poor fit. We tested modern designs of GPS collars on n = 105 horses and n = 60 burros for 4 years in five populations (3 horse, 2 burro) across the western United States, to assess whether collars posed welfare risks to horses or burros. We found no difference in survival of collared versus uncollared mares and jennies, and no difference in survival of their foals. In 4036 of 4307 observations for horses (93.7%) and 2115 of 2258 observations for burros (93.6%), collars were observed symmetrical, maintaining proper fit on the neck. Fur effects from collars (sweaty neck, indented fur, broken fur) were seen in 3% of horse observations and 25% of burro observations. Superficial effects (chafes and marks on skin surface) were seen in 2% of horse observations and 11% of burro observations; no severe effects from collars were seen. Body condition was not affected by collars; mean body condition of collared horses was 4.70 ± 0.54 (mean ± s.d) and 4.71 ± 0.65 for collared burros. Behavior results indicated minimal effects; collared horses stood slightly more than uncollared, and collared burros stood and foraged more in one population, but not in the other. For 6.3% of observations of horses and 6.4% of observations of burros, we found an effect of time wearing a collar on the cumulative sum of fur effects which increased over time (burros: r s = 0.87, P = <0.0001; horses: r s = 0.31, P = 0.002). Burros also showed an increase over time in the number of superficial effects, but horses did not. Collars occasionally moved into the wrong position, shifting forward over the ears; we observed this on 19 horses and 1 burro. Of those, most collars went over the ears in summer ( n = 12). All collars were equipped with a remote release mechanism as well as a timed-release mechanism for redundancy, thus removed when observed in wrong position to avoid rubbing or discomfort. Our finding of no consequential physical effects in 98% of horse observations, and 89% of burro observations suggests the consequences of collars on free-roaming equid welfare and survival is biologically insignificant, although collars should be monitored regularly and continue to be equipped with a remote release mechanism to remove a collar if needed. With frequent welfare-driven, visual monitoring, collaring of free-roaming equids can be a safe and useful tool to increase our understanding of their spatial ecology, demography, habitat use, behavior, and interactions with other wildlife.

Arizona, Utah, Wyoming↗
USGS2024

Rainfall reduces the potential for competitive suppression of a globally endangered ungulate by livestock

Protected areas often are too small to house populations of wide-ranging species. Viability of wildlife populations therefore depends on whether interactions with humans and their land uses are negative, neutral, or positive. In central Iran, we measured interactions between globally endangered onagers (Equus hemionus onager) and livestock by analyzing remotely-sensed vegetation metrics within livestock grazing areas, tracking 9 animals with GPS telemetry, and assessing onagers' diet quality through analysis of fecal samples. Resource selection by onagers depended both on season and the presence of livestock. During the dry season, livestock reduced forage (some combination of forage biomass and forage quality) compared to pre-grazing periods, demonstrating potential for competitive suppression of onagers by livestock when resources are scarce. Additionally, and during both seasons, selection for forage by onagers was accentuated at night when livestock were absent, indicating onager avoidance of livestock. During the wet season, onagers exposed to livestock exhibited higher-quality diets than those that did not co-occur with livestock, suggesting that livestock grazing may potentially enhance forage quality for onagers. Consequently, collaboration with pastoralists to regularly rotate the locations of dry and wet season leases could alleviate negative effects of livestock grazing on onagers. Similar to other cases in multi-use landscapes, temporal shifts in the strength of competition—driven by diel cycles and seasonal rainfall—may characterize wildlife-livestock interactions in Iran and elsewhere in Asian rangelands. Our study highlights the possibility that conservation of an endangered mammal could be compatible with livestock production, at least during wet seasons.

Bahram-e-Goor Protected Area (BPA), Qatrouiyeh Nat↗
USGS2024

A metapopulation strategy to support long term conservation of genetic diversity in Department of the Interior bison

Once numbering in the tens of millions, plains bison ( Bison bison bison ) were nearly driven to extinction with only a few hundred individuals remaining by the late 19th century. Plains bison have since recovered to approximately 20,000 animals managed in conservation herds throughout North America, yet substantial challenges to their recovery remain. The Department of the Interior (DOI) is working with diverse partners to steward approximately 11,000 bison in 18 conservation herds across 12 states. Most herds exist in areas without native predators, and removals are required to keep herd sizes at or below carrying capacity. The loss of genetic diversity within bison, and the fact that most DOI herds are relatively small and isolated from each other with no opportunity for natural gene flow, raises concerns about maintaining genetic diversity over the long term. Connecting populations through gene flow (i.e., creating a metapopulation) can minimize loss of genetic diversity, both within and across populations. Management of DOI bison conservation herds has historically varied across bureaus and conservation units. Adopting a national perspective on bison conservation was identified as a priority in the 2008 Department of the Interior Bison Conservation Initiative (BCI). The concept of metapopulation management as a potential tool to maximize the conservation of genetic diversity among DOI herds was first described in this 2008 Initiative and was specifically encouraged in the 2010 DOI Bison Conservation Genetics Workshop report (Dratch and Gogan 2010). In the 2020 BCI, the DOI re-affirmed its commitment to conserving bison as native, North American wildlife. This document establishes a framework for a nationally coordinated strategy for bison managed by the DOI to support the genetic conservation goals outlined in the 2020 BCI. This is a decisionmaking framework that guides managers through the process of determining when and how to consider translocations. Decisions and actions within the framework are informed by analysis and interpretation of data housed in an integrated, relational database that will be initially populated with the most current data and updated annually thereafter. It provides science-based guidance on how to conserve DOI bison genetic diversity through strategic translocations, while also considering cattle introgression and bison health. We illustrate how this Strategy can be used to guide the establishment of new conservation herds and discuss what it means to be a DOI partner. Finally, this is intended to be used as a living document that will evolve as needs and technologies change.

Science Report↗