Abstract. Intraguild predation (IGP) by a dominant predator can drive the spatial dynamics of a subordinate predator and may explain space-use patterns that deviate from theoretical predictions that species will use areas that maximize the availability of limited resources (resource availability hypothesis). Intraguild predation may suppress the distribution and abundance of mesopredators, but spatial resource partitioning may facilitate coexistence, with the subordinate carnivore utilizing suboptimal habitats. In arid systems, free-standing water was historically scarce, limiting the distribution of larger-bodied predators and offering large areas of refugia for smaller, arid-adapted species, such as the kit fox (Vulpes macrotis). In these systems, the development of artificial water sources may facilitate an increase in the distribution and abundance of larger carnivores (e.g., coyotes [Canis latrans]), perhaps to the detriment of kit foxes. We coupled noninvasive genetic sampling and dynamic occupancy models to evaluate the spatial dynamics of kit foxes and their intraguild predators, coyotes, in western Utah, United States. We evaluated the influence of habitat characteristics on coyote occupancy patterns, and then investigated the role of habitat and coyotes on kit fox space use at multiple scales. Coyote occupancy was unrelated to water availability, but was positively related to the proportion of shrubland and woodland cover, a pattern consistent with predictions of the resource availability hypothesis. Supporting predictions of IGP theory, kit fox occupancy was negatively related to shrubland and woodland cover, minimizing overlap with land-cover types favoring coyote occupancy. Furthermore, kit fox probability of local extinction was positively related to coyote activity. Interestingly, kit fox detection was positively related to coyote activity (i.e., kit fox detection was higher on spatial surveys with greater coyote sign), suggesting that at finer scales, kit foxes utilized riskier habitats to secure sufficient resources. Our results identified two alternative states predicted by IGP theory (i.e., intraguild predator dominated and coexistence of intraguild predator and intraguild prey) in a single system and elucidated the importance of considering dynamic processes and scale when investigating IGP.

Scat surveys are commonly used to monitor carnivore populations. Scats of sympatric carnivores can be difficult to differentiate and field‐based identification can be misleading. We evaluated the success of field‐based species identification for scats of 2 sympatric carnivores—coyotes (Canis latrans) and kit foxes (Vulpes macrotis). We conducted scat surveys in the Great Basin desert of Utah, USA, during the winter and summer of 2013, and we detected 1,680 carnivore scats. We classified scats based on field identification, recorded morphometric measurements, and collected fecal DNA samples for molecular species identification. We subsequently evaluated the classification success of field identification and the predictive power of 2 nonparametric classification techniques—k‐nearest neighbors and classification trees—based on scat measurements. Overall, 12.2% of scats were misclassified by field identification, but misclassifications were not equitable between species. Only 7.1% of the scats identified as coyote with field identification were misclassified, compared with 22.9% of scats identified as kit fox. Results from both k‐nearest neighbor and classification‐tree analyses suggest that morphometric measurements provided an objective alternative to field identification that improved classification of rarer species. Overall misclassification rates for k‐nearest neighbor and classification‐tree analyses were 11.7% and 7.5%, respectively. Using classification trees, misclassification was reduced for kit foxes (8.5%) and remained similar for coyotes (7.2%), relative to field identification. Although molecular techniques provide unambiguous species identification, classification approaches may offer a cost‐effective alternative. We recommend that monitoring programs employing scat surveys utilize molecular species identification to develop training data sets and evaluate the accuracy of field‐based and statistical classification approaches. © 2015 The Wildlife Society.

Kit fox (Vulpes macrotis Merriam, 1888) populations in the Great Basin Desert have declined and are of increasing concern for managers. Increasing coyote (Canis latrans Say, 1823) abundance and subsequent intraguild interactions may be one cause for this decline. Concurrent monitoring of carnivores is challenging and therefore rarely conducted. One possible solution for monitoring elusive carnivores is using noninvasive genetic sampling. We used noninvasive genetic sampling to collect fecal DNA from kit foxes and coyotes and estimate their densities from 2013–2014 in Utah, USA. We identified individuals based on microsatellite genotypes and estimated density with multisession spatially explicit capture–recapture models. Mean kit fox density was 0.02 foxes·km−2, while coyote densities were up to four times greater (0.07–0.08 coyotes·km−2). Kit fox densities were significantly lower than densities in the 1950s but were comparable with estimates from the late 1990s, suggesting that populations may be stabilizing after a precipitous decline. Our kit fox density estimates were among the lowest documented for the species. Our coyote density estimate was the first reported in our region and revealed that despite seemingly high abundance, densities are low compared with other regions. Our results suggested that kit foxes may be able to coexist with coyotes.

Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide-ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture-recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1-112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture-recapture analyses, overall cost-efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates.

Analyzing predator scats for the presence of prey is a common noninvasive approach to understanding trophic interactions. Morphological analysis of prey remains has been the prevailing method of diet analysis, but molecular methods are becoming more widely used. Previous analyses suggest molecular methods detect target prey species more frequently than morphological methods. We compared these methods by analyzing coyote (Canis latrans) scats-collected in Tooele County, Utah, USA, in the winter of 2014-for leporids, a taxonomic group for which a molecular species identification test has been developed. We included 25 scats in which leporids were detected and 25 scats in which leporids were not detected by morphological methods. Additionally, because few studies have explored the effect of fecal sampling protocols on prey DNA detection, we analyzed subsamples taken from 5 locations on each scat to compare prey detection frequencies. We found that molecular analysis detected leporid prey in scats at a rate similar to or greater than morphological analysis, depending on the number of fecal sampling locations considered. Of the single samples, the homogenized (46%) and side (44%) samples provided the greatest rates of leporid prey DNA detection, followed by the ends (mean across both ends ¼ 35%) and center (38%) of scats. When multiple sampling locations were considered, the homogenized-side combination (70%) had a detection rate similar to when all sampling locations were considered (76%). Our results indicate that molecular analysis detected prey more frequently than morphological analysis, but that prey detection was not equitable among fecal sampling locations and multiple sampling locations may be required. Ó 2017 The Wildlife Society.

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 United States. For our first annual survey, we compiled data across all 50 states during a 14‐week period (17 August–24 November of 2019). We sampled wildlife at 1,509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian’s eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the United States. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban–wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot‐usa, as will future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species‐specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.

Resource partitioning between kit foxes (Vulpes macrotis) and coyotes (Canis latrans): a comparison of historical and contemporary dietary overlapUnder conditions leading to coexistence, competition with a dominant species may limit the distribution and density of a subordinate carnivore (Hardin 1960;Schoener 1983; Glen and Dickman 2008;Sidorovich et al. 2010), which can make the population less resilient to changes in habitat or resource availability. Thus, the ability to minimize competition through resource partitioning may be critical for the long-term persistence of specialist carnivore populations facing novel competitive pressures.Resource partitioning is a multidimensional process involving temporal, spatial, and/or dietary shifts in a species' resource use, which lessens niche overlap among species (Schoener 1974; Garneau et al. 2007; Kamler et al. 2012) and reduces negative encounters between were believed to be on increasing and decreasing long-term trajectories, respectively (Arjo et al. 2007). Consequently, we hypothesized we would see an overall decrease in dietary overlap between the two species, reflecting increased competition for prey and, accordingly, an increased degree of dietary resource partitioning. It has been hypothesized that water is a limiting factor in this region (Arjo et al. 2007), and that kit foxes and coyotes select for prey that will maximize water intake (Golightly and Ohmart 1984; Kozlowski et al. 2012). We predicted that coyotes would limit kit fox access to higher-quality dietary prey, such as leporids, which contain higher water content per capture than smaller mammals, such as kangaroo rats (species of genus Dipodomys Gray, 1841) and other rodents (species of the order Rodentia Bowdich, 1821), and non-mammalian prey (e.g., insects, reptiles, birds-Pond 1978). We predicted that kit foxes would respond by increasing their use of small mammals and non-mammalian prey. Materials and methods Study areaThis study was conducted in the Great Basin Desert of western Utah. Sampling occurred on the U.S Army's Dugway Proving Ground and surrounding federal lands managed by the U.S. Dietary overlap was calculated using the Morisita-Horn Similarity Index (hereafter, M-H Index-Horn 1966), in which overlap was based on the proportion of prey classes in the diet, and was measured on a scale of 0 (no dietary overlap) to 1 (complete dietary overlap). All 11 dietary classes were included in measurements of overlap and diversity. Seasonal and annual dietary overlap was assessed within each canid species between the contemporary and historical periods.Dietary overlap was also assessed between kit foxes and coyotes for the contemporary sampling period. Breadth of dietary diversity for contemporary samples was calculated using the ShannonWeiner Diversity Index (hereafter, H'-Shannon 1948). Dietary diversity was measured both annually and for winter and summer sampling periods, and differences in diversity were tested for significance using Hutcheson's t-test (Hutcheson 1970). Differences in...

Development and evaluation of noninvasive methods for monitoring species distribution and abundance is a growing area of ecological research. While noninvasive methods have the advantage of reduced risk of negative factors associated with capture, comparisons to methods using more traditional invasive sampling is lacking. Historically kit foxes (Vulpes macrotis) occupied the desert and semi-arid regions of southwestern North America. Once the most abundant carnivore in the Great Basin Desert of Utah, the species is now considered rare. In recent decades, attempts have been made to model the environmental variables influencing kit fox distribution. Using noninvasive scat deposition surveys for determination of kit fox presence, we modeled resource selection functions to predict kit fox distribution using three popular techniques (Maxent, fixed-effects, and mixed-effects generalized linear models) and compared these with similar models developed from invasive sampling (telemetry locations from radio-collared foxes). Resource selection functions were developed using a combination of landscape variables including elevation, slope, aspect, vegetation height, and soil type. All models were tested against subsequent scat collections as a method of model validation. We demonstrate the importance of comparing multiple model types for development of resource selection functions used to predict a species distribution, and evaluating the importance of environmental variables on species distribution. All models we examined showed a large effect of elevation on kit fox presence, followed by slope and vegetation height. However, the invasive sampling method (i.e., radio-telemetry) appeared to be better at determining resource selection, and therefore may be more robust in predicting kit fox distribution. In contrast, the distribution maps created from the noninvasive sampling (i.e., scat transects) were significantly different than the invasive method, thus scat transects may be appropriate when used in an occupancy framework to predict species distribution. We concluded that while scat deposition transects may be useful for monitoring kit fox abundance and possibly occupancy, they do not appear to be appropriate for determining resource selection. On our study area, scat transects were biased to roadways, while data collected using radio-telemetry was dictated by movements of the kit foxes themselves. We recommend that future studies applying noninvasive scat sampling should consider a more robust random sampling design across the landscape (e.g., random transects or more complete road coverage) that would then provide a more accurate and unbiased depiction of resource selection useful to predict kit fox distribution.