Kit Fox Research Articles

Dryland state transitions alter trophic interactions in a predator-prey system.

Environmental change is expected to alter trophic interactions and food web dynamics with consequences for ecosystem structure, function and stability. However, the mechanisms by which environmental change influences top-down and bottom-up processes are poorly documented. Here, we examined how environmental change caused by shrub encroachment affects trophic interactions in a dryland. The predator-prey system included an apex canid predator (coyote; Canis latrans), an intermediate canid predator (kit fox; Vulpes macrotis), and two herbivorous lagomorph prey (black-tailed jackrabbit, Lepus californicus; and desert cottontail, Sylvilagus audubonii) in the Chihuahuan Desert of New Mexico, USA. We evaluated alternative hypotheses for how shrub encroachment could affect habitat use and trophic interactions, including (i) modifying bottom-up processes by reducing herbaceous forage, (ii) modifying top-down processes by changing canid space use or the landscape of fear experienced by lagomorph prey and (iii) altering intraguild interactions between the dominant coyote and the intermediate kit fox. We used 7 years of camera trap data collected across grassland-to-shrubland gradients under variable precipitation to test our a priori hypotheses within a structural equation modelling framework. Lagomorph prey responded strongly to bottom-up pulses during years of high summer precipitation, but only at sites with moderate to high shrub cover. This outcome is inconsistent with the hypothesis that bottom-up effects should be strongest in grasslands because of greater herbaceous food resources. Instead, this interaction likely reflects changes in the landscape of fear because perceived predation risk in lagomorphs is reduced in shrub-dominated habitats. Shrub encroachment did not directly affect predation pressure on lagomorphs by changing canid site use intensity. However, site use intensity of both canid species was positively associated with jackrabbits, indicating additional bottom-up effects. Finally, we detected interactions between predators in which coyotes restricted space use of kit foxes, but these intraguild interactions also depended on shrub encroachment. Our findings demonstrate how environmental change can affect trophic interactions beyond traditional top-down and bottom-up processes by altering perceived predation risk in prey. These results have implications for understanding spatial patterns of herbivory and the feedbacks that reinforce shrubland states in drylands worldwide.

Spatiotemporal partitioning between the endangered San Joaquin kit fox and a novel mesocarnivore community in the urban environment as revealed by camera traps

Urbanization has led to the rapid formation of novel biotic communities, which via interspecific interactions, may affect niche partitioning dynamics of native, sensitive species. The endangered San Joaquin kit fox (Vulpes macrotis mutica; hereafter ‘kit fox’) is a small mesocarnivore inhabiting urban areas of the southern Central Valley of California alongside other urban mesocarnivores. These other species may pose challenges for kit foxes due to a potential lack of evolved mechanisms of defense or avoidance. To address this notion, we evaluated evidence of temporal and spatial partitioning between the kit fox and its potential predators and competitors in an urban environment. We predicted that spatial and temporal overlap would be lower between kit foxes and their predators than with their competitors. We used camera traps with scent lures at high school and college campuses across the southern San Joaquin Valley to monitor the visitation patterns of urban mesocarnivores from 2020 to 2022. We used generalized linear mixed models and AIC model selection to evaluate spatial relationships between kit foxes and other mesocarnivores and we used temporal overlap coefficients and peak activity analysis to evaluate temporal overlap. Kit foxes exhibited low spatial overlap (negative association) with Virginia opossums (Didelphis virginiana) and high spatial overlap (positive association) with domestic cats (Felis catus), domestic dogs (Canis lupus familiaris), northern raccoons (Procyon lotor), and striped skunks (Mephitis mephitis). Kit foxes exhibited low to moderate levels of temporal overlap with other species, the least of which occurring with potential predators (i.e., coyotes (C. latrans), domestic dogs). Our findings support the temporal partitioning and partially support the spatial partitioning hypothesis as potential mechanisms to promote coexistence among mesocarnivores in an urban environment.

Social and genetic relationships among individuals in urban kit fox social groups

Smaller canids, such as most foxes, individually hunt small prey, and therefore, social groups typically consist of just a mated pair. However, these smaller canids occasionally form groups in which the members have been presumed to be genetically or socially related. We studied social and genetic relationships among urban San Joaquin kit fox ( Vulpes macrotis mutica Merriam, 1902) groups in Bakersfield, California. Of 59 groups, 42.4% had extra adults in addition to the parents. Foxes were field classified as either mothers, fathers, helpers (extra adults), or pups. We then assessed relatedness of foxes within social groups using 11 microsatellites in DNA from tissue or hair samples. Mated pairs were significantly less related than mothers and helpers, with fathers and helpers being intermediate. Twelve pairs of females were mother–daughter dyads, but we also found two cases of sisters and two cases where the females were unrelated. Pups were always related to a female identified as their mother. Father–pup pairs were less related than mother–pup pairs, with helper–pup pairs being intermediate. The extra-pair paternity rate (multiple fathers per litter) was 39%. The social flexibility exhibited by kit foxes may increase their resiliency to marked fluctuations in resource availability, thereby reducing extinction risk.

Kit foxes demonstrate adaptive compromise characteristics under intraguild predation pressure by coyotes in the Great Basin desert

Coyotes (Canis latrans) are believed to contribute to declining kit fox (Vulpes macrotis) numbers in the Great Basin desert through intraguild predation. Intraguild prey have been shown to exhibit adaptive compromise, whereby an animal increases selection for risky, but food-rich areas during times of food stress (i.e. winter). We evaluated the habitat selection of kit foxes in the Great Basin desert to elucidate if they demonstrated adaptive compromise as a method of coexisting with coyotes. We created 2nd order resource selection functions to analyze kit fox habitat selection associated with coyote relative probability of use (RPU), prey abundance, and type of soil substrate. In the summer, we found that kit fox selection for areas of relatively more abundant prey was not significant, and there was a small positive selection for coyote RPU. In the winter, we found a positive relationship between kit fox selection and prey abundance as well as a stronger selection for coyote RPU. These findings do follow the pattern of adaptive compromise. We also found kit foxes selected for silty and sandy soils, which are conducive to den construction, as they use dens seasonally for breeding but also year-round for multiple uses, including refugia from predators and extreme heat. Soil substrate appeared to be an important factor impacting kit fox habitat selection.

A Novel Hazard for an Endangered Fox in a Novel Environment.

Animals colonizing novel environments can encounter novel hazards. Endangered San Joaquin kit foxes (Vulpes macrotis mutica) are found in the cities of Bakersfield and Taft in central California, USA. We documented 66 incidents of kit foxes becoming entangled in sports netting (e.g., soccer nets, batting-cage nets) occurring from the 1980s through 2022. Overall, 25 of the foxes died. Adults were more likely to get entangled in soccer nets, whereas pups (<1 yr) were more likely to get entangled in batting-cage nets. Pups are more likely to die while entangled, probably due to smaller body mass and lower energy reserves. The reasons that kit foxes get entangled in netting were unclear, although incidents involving batting-cage netting and pups may be due to natal dens being located under or near batting cages. At current rates, this hazard is unlikely to limit urban kit fox populations. However, losses of this endangered species should be minimized and the incidents are easily mitigated by dropping or lifting nets when not in use.

Comparison of San Joaquin kit fox den and California ground squirrel burrow attributes

Endangered San Joaquin kit foxes (Vulpes macrotis mutica; SJKF) and California ground squirrels (Otospermophilus beecheyi; CAGS) occur sympatrically in many locations. CAGS can constitute a nuisance species and control strategies have included lethal measures administered within CAGS burrows. These measures could harm or kill a SJKF if mistakenly applied to an occupied SJKF den. To identify attributes to distinguish between SJKF dens and CAGS burrow, we assessed dimensions, penetration depths by 9.7-cm and 7.5-cm spheres, ejecta patterns, and the presence of various types of sign at 65 dens to which radiocollared SJKF were tracked and at 80 burrows that CAGS were observed to enter. Mean entrance height, width, and circumference all were significantly larger for SJKF den entrances. However, the ranges of values for all dimensions for the CAGS burrows completely encompassed the ranges for the SJKF dens. Penetration depths with the 7.5-cm sphere were similar for SJKF dens and CAGS burrows. The 9.7-cm sphere could not be inserted in over half of CAGS burrows and exceeded 1 m in depth in over half of the SJKF dens. Most SJKF dens had dirt berms but so did over half of the CAGS burrows. SJKF scats, prey remains, CAGS scats, and trash were observed at both SJKF dens and CAGS burrows although at different frequencies. CAGS tracks were only observed at seven CAGS burrows. None of the attributes we assessed provided unequivocal criteria for distinguishing between SJKF dens and CAGS burrows. Also, SJKF occasionally usurp CAGS burrows and CAGS occasionally move into vacant SJKF dens. Therefore, administering lethal control measures within burrows should be avoided as it presents too great a risk to SJKF as well as the many other species that also use CAGS burrows.

Syntopy between Endangered San Joaquin Kit Foxes and Potential Competitors in an Urban Environment.

The endangered San Joaquin kit fox (Vulpes macrotis mutica; SJKF) occurs in the city of Bakersfield, CA, where several putative competitors also occur, including domestic cats (Felis catus), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), and opossums (Didephis virginiana). We used data from a multi-year (2015-2022) city-wide camera station survey to assess whether the other species were simply sympatric with SJKF or coexisting syntopically (i.e., occurring in the same habitats without apparent competition). Annual detection rates for the other species were not correlated with SJKF rates either within SJKF habitat suitability categories (low, medium, and high) or for all categories combined. Also, detection rates for the other species did not increase in response to a significant decline in SJKF abundance caused by sarcoptic mange. The use of all SJKF habitat suitability categories by the other species and co-detections with SJKF at camera stations indicate high spatial overlap. Interference and exploitative competition between the species are apparently negligible, likely due to similar body sizes and high resource abundance. Thus, SJKF and the other species appear to be coexisting syntopically in the urban environment, resulting in a significant additional SJKF population that facilitates range-wide conservation and recovery of this endangered species.

Vector-Borne Disease in Wild Mammals Impacted by Urban Expansion and Climate Change.

Ecologies of zoonotic vector-borne diseases may shift with climate and land use change. As many urban-adapted mammals can host ectoparasites and pathogens of human and animal health concern, our goal was to compare patterns of arthropod-borne disease among medium-sized mammals across gradients of rural to urban landscapes in multiple regions of California. DNA of Anaplasma phagocytophilum was found in 1-5% of raccoons, coyotes, and San Joaquin kit foxes; Borrelia burgdorferi in one coyote, rickettsiae in two desert kit foxes, and Yersinia pestis in two coyotes. There was serological evidence of rickettsiae in 14-37% of coyotes, Virginia opossums, and foxes; and A. phagocytophilum in 6-40% of coyotes, raccoons, Virginia opossums, and foxes. Of six flea species, one Ctenocephalides felis from a raccoon was positive for Y. pestis, and Ct. felis and Pulex simulans fleas tested positive for Rickettsia felis and R. senegalensis. A Dermacentor similis tick off a San Joaquin kit fox was PCR-positive for A. phagocytophilum. There were three statistically significant risk factors: risk of A. phagocytophilum PCR-positivity was threefold greater in fall vs the other three seasons; hosts adjacent to urban areas had sevenfold increased A. phagocytophilum seropositivity compared with urban and rural areas; and there was a significant spatial cluster of rickettsiae within greater Los Angeles. Animals in areas where urban and rural habitats interconnect can serve as sentinels during times of change in disease risk.

Efficacy of machine learning image classification for automated occupancy‐based monitoring

AbstractRemote cameras have become a widespread data‐collection tool for terrestrial mammals, but classifying images can be labor intensive and limit the usefulness of cameras for broad‐scale population monitoring. Machine learning algorithms for automated image classification can expedite data processing, but image misclassifications may influence inferences. Here, we used camera data for three sympatric species with disparate body sizes and life histories – black‐tailed jackrabbits (Lepus californicus), kit foxes (Vulpes macrotis), and pronghorns (Antilocapra americana) – as a model system to evaluate the influence of competing image classification approaches on estimates of occupancy and inferences about space use. We classified images with: (i) single review (manual), (ii) double review (manual by two observers), (iii) an automated‐manual review (machine learning to cull empty images and single review of remaining images), (iv) a pretrained machine‐learning algorithm that classifies images to species (base model), (v) the base model accepting only classifications with ≥95% confidence, (vi) the base model trained with regional images (trained model), and (vii) the trained model accepting only classifications with ≥95% confidence. We compared species‐specific results from alternative approaches to results from double review, which reduces the potential for misclassifications and was assumed to be the best approximation of truth. Despite high classification success, species‐level misclassification rates for the base and trained models were sufficiently high to produce erroneous occupancy estimates and inferences related to space use across species. Increasing the confidence thresholds for image classification to 95% did not consistently improve performance. Classifying images as empty (or not) offered a reasonable approach to reduce effort (by 97.7%) and facilitated a semi‐automated workflow that produced reliable estimates and inferences. Thus, camera‐based monitoring combined with machine learning algorithms for image classification could facilitate monitoring with limited manual image classification.

MOVEMENTS BY SAN JOAQUIN KIT FOXES (VULPES MACROTIS MUTICA) BETWEEN URBAN AND NONURBAN HABITATS: IMPLICATIONS FOR INTERPOPULATION DISEASE TRANSFER.

Sarcoptic mange epidemics erupted in two of the remaining populations of endangered San Joaquin kit foxes (Vulpes macrotis mutica). Both populations are in urban habitats in the cities of Bakersfield and Taft, California, USA. The risk of disease spread from the two urban populations to nearby nonurban populations, and then throughout the species range, is of considerable conservation concern. To date, mange has not been detected in any nonurban populations despite considerable surveillance effort. The reasons for the lack of detections of mange among nonurban foxes are unknown. We monitored urban kit fox movements using geographic positioning system (GPS) collars to test the hypothesis that urban foxes were not venturing into nonurban habitats. Of 24 foxes monitored December 2018 to November 2019, 19 (79%) made excursions from urban into nonurban habitats from 1-124 times. The mean number of excursions per 30 d was 5.5 (range 0.1-13.9 d). The mean proportion of locations in nonurban habitats was 29.0% (range 0.6-99.7%). The mean maximum distance that foxes traveled into nonurban areas from the urban-nonurban interface was 1.1 km (range 0.1-2.9 km). Mean number of excursions, proportion of nonurban locations, and maximum distance into nonurban habitats were similar between Bakersfield and Taft, females and males, and adults and juveniles. At least eight foxes apparently used dens in nonurban habitats; shared use of dens may be an important mode of mange mite transmission between conspecifics. Two of the collared foxes died of mange during the study and two others had mange when captured at the end of the study. Three of these four foxes had made excursions into nonurban habitats. These results confirm a significant potential for mange to spread from urban to nonurban kit fox populations. We recommend continued surveillance in nonurban populations and continued treatment efforts in the affected urban populations.

Spatio-temporal and transmission dynamics of sarcoptic mange in an endangered New World kit fox.

Sarcoptic mange poses a serious conservation threat to endangered San Joaquin kit foxes (Vulpes macrotis mutica). After first appearing in Bakersfield, California in spring 2013, mange reduced the kit fox population approximately 50% until the epidemic ended with minimally detectable endemic cases after 2020. Mange is lethal and thus, with such a high force of infection and lack of immunity, it remains unclear why the epidemic did not burn itself out rapidly and how it persisted so long. Here we explored spatio-temporal patterns of the epidemic, analyzed historical movement data, and created a compartment metapopulation model (named "metaseir") to evaluate whether movement of foxes among patches and spatial heterogeneity would reproduce the eight years epidemic with 50% population reduction observed in Bakersfield. Our main findings from metaseir were that: 1) a simple metapopulation model can capture the Bakersfield-like disease epidemic dynamics even when there is no environmental reservoir or external spillover host, 2) the most impactful parameter on persistence and magnitude of the epidemic is the projection, β/αβ (transmission over decay rate of transmission over space), 3) heterogeneity in patch carrying capacities changes the critical value of the projection needed to achieve an epidemic but makes little difference to epidemic persistence time, and 4) the epidemic is relatively insensitive to birth rates and density vs. frequency-dependent transmission. Our model can help guide management and assessment of metapopulation viability of this vulpid subspecies, while the exploratory data analysis and model will also be valuable to understand mange in other, particularly den-occupying, species.

Potential habitat and carrying capacity of endangered San Joaquin kit foxes in an urban environment: implications for conservation and recovery

The San Joaquin kit fox (Vulpes macrotis mutica; SJKF) is federally endangered due to profound habitat loss. A population of SJKF occurs in the urban environment in the city of Bakersfield, California, and may be important for SJKF conservation. We conducted a systematic survey using automated camera stations and occupancy analysis to identify suitable habitat for SJKF in Bakersfield and to estimate a conceptual carrying capacity in the urban environment. We identified high, medium, and low suitability habitat totaling 121 km2, 196 km2, and 40 km2, respectively. Based on a mean urban kit fox home range size of 0.78 km2 and an assumption of two adults in high suitability home ranges and one adult in medium suitability ranges, we estimated the adult carrying capacity in Bakersfield to be 561 foxes. This estimate seems plausible as the number of adult SJKF in Bakersfield was estimated to be 381 in 2015, and the number of foxes already had been reduced by a sarcoptic mange epidemic that began two years earlier. A carrying capacity of 561 adults would increase the estimated range-wide carrying capacity by as much as 38%. Adult density estimates derived for the urban SJKF population based on the carrying capacity (1.57/km2) and home range size (2.56/km2) were higher than estimates for foxes in natural habitats. The urban SJKF population in Bakersfield is substantial and therefore could contribute significantly to conservation and recovery efforts for SJKF. Given our results, a potential conservation strategy may be to encourage or even establish additional urban SJKF populations.

Intraguild Competition between Endangered Kit Foxes and a Novel Predator in a Novel Environment.

Simple SummaryA population of endangered San Joaquin kit foxes inhabits the urban environment in the city of Bakersfield, California, United States. Non-native red foxes, a larger competitor, also occur in Bakersfield and are a potential threat to kit foxes. Based on scat analysis, dietary overlap between the two species is high and red foxes have usurped kit fox dens. Based on logistic regression, habitat attributes generally were similar between grid cells used by each species. However, kit foxes tended to use areas with smaller open spaces and more human activity. We also found that the two species almost never overlapped temporally when using the same grid cells. Because of this temporal separation in addition to an abundance of food and dens in the urban environment, competition from red foxes does not currently appear to be a significant threat to kit foxes.A population of endangered San Joaquin kit foxes inhabits the urban environment in the city of Bakersfield, California, United States. This population is considered important for the conservation and recovery of this species. In this novel environment, kit foxes encounter a novel competitor, that being non-native red foxes. We examined exploitative and interference competition between these two species. Based on scat analysis, both species consumed similar foods and dietary overlap was high. Red foxes also were found to usurp kit fox dens. Direct mortality to kit foxes from red foxes appears to be rare. Kit foxes and red foxes also appear to overlap spatially, although we found evidence of temporal partitioning of shared space. Based on binary logistic regression modeling, habitat attributes in grid cells used by the two species generally were similar, consistent with the spatial overlap. However, differences in specific attributes indicated that kit foxes are more likely to use areas with smaller open spaces and more human activity compared to red foxes. Competition from red foxes may be mitigated by several factors. Critical resources such as food and dens may be sufficiently abundant such that they are not a limiting factor. Some degree of spatial segregation and temporal partitioning of shared space may reduce interference competition. These factors may facilitate coexistence, and consequently, red foxes do not currently appear to constitute a significant competitive risk to this important population of endangered San Joaquin kit foxes.

Drought and coyotes mediate mesopredator response to human disturbance

AbstractMesopredators in western North America are facing major changes to their ecosystems, including drought and the expansion of human disturbance. To balance resource needs and risk‐taking on the landscape, mesopredators are likely to shift their habitat use and interspecies interactions. As part of a large‐scale study to help evaluate responses of terrestrial wildlife to severe drought, the California Department of Fish and Wildlife surveyed mesopredator presence across 585 sites in the Mojave Desert (MD) and Central Valley (CV) ecoregions of California. This study spanned a drought year (2016) and a post‐drought year (2017), providing the opportunity to investigate how drought and interspecific interactions may mediate spatial patterns of mesopredator occurrence across a continuum of human disturbance levels. We used single‐season, single‐species, and conditional two‐species occupancy models to elucidate these relationships in both ecoregions. We examined the occupancy and detection of coyotes (Canis latrans) and smaller mesopredators, including bobcats (Lynx rufus) in both ecoregions, raccoons (Procyon lotor) in the CV, and desert kit foxes in the MD (Vulpes macrotis arsipus). The presence of coyotes influenced the detection probability of all other mesopredator species, and the influence of drought varied by species and ecoregion. Detection of mesopredators in the CV was typically higher in 2016, especially at low disturbance sites, suggesting species may have become more active during the drought to meet resource needs. However, detection of mesopredators in the MD tended to increase after the drought, suggesting a response to an increase in resources (e.g., prey). Coyotes in the MD became more detectable in high human disturbance in 2016 and less detectable in 2017, possibly increasing activity during the drought in human‐disturbed areas to obtain anthropogenic resources. Drought not only affects individual species and their relationships to human disturbance, but it can also influence their interspecies interactions and use of different landscape features.

Demographic and functional responses of kit foxes to changes in prey abundance

Many carnivores exhibit demographic and functional responses to changes in prey abundance. Demographic responses often include changes in population size, litter size, and recruitment of young into the adult population. Functional feeding responses are commonly reported for many carnivore species. We investigated demographic and functional responses of kit foxes ( Vulpes macrotis Merriam, 1888) to changes in prey abundance during 2010–2013 in western Utah, USA. Between 2010 and 2013, litter size averaged 3.9 (±1.4) pups/litter. Survival rates of kit fox pups were 0.07, 0.01, 0.46, and 0.16, respectively, and there was a correlation between pup survival rates and rodent abundance; leporid (family Leporidae Fischer, 1817) abundance did not influence pup survival. There was a functional response as occurrence of kangaroo rat in the diet closely followed changes in kangaroo rat abundance. The occurrence of rodents in kit fox diet followed declines in rodent abundance (excluding Dipodomys spp. Gray, 1841). Leporid consumption by kit foxes was not correlated to leporid density. Kit fox survival was dependent on rodent abundance and more specifically, kangaroo rats. Understanding which population parameters of kit foxes are influenced by prey is critical for the conservation of this native mesocarnivore.

Modeling habitat use and potential distribution of kit fox in the Trans‐Pecos, Texas

AbstractManagement of a species requires knowledge of their distribution and the environmental factors that influence their use of an area. The kit fox (Vulpes macrotis) is a small fox species endemic to the threatened desert grasslands of the western United States and northern Mexico. Little information exists on the status and distribution of kit fox in Texas, USA; however, researchers have documented population declines in the closely related swift fox (Vuples velox) in the Texas Panhandle. Therefore, our objectives were to survey areas of potential kit fox habitat using remote trail cameras to determine use and detection rates for kit fox, evaluate and quantify environmental effects on habitat use, and map potential distribution of kit fox habitat throughout the Trans‐Pecos using results from the preceding occupancy analysis. We conducted camera surveys at 732 baited sites from March 2018 to March 2020, with each survey lasting 14 days on average (~10,248 camera‐days). We detected kit fox at 99 of 732 camera survey sites. We divided surveys into 3‐day sampling occasions and fit single‐season occupancy models to test for an effect of sampling occasion and season on detection and for effects of slope, elevation, shrub height, shrub canopy cover, percent litter, percent herbaceous cover, and bare ground on habitat use. Overall detection was 0.31 ± 0.001 (SE) and was influenced by sampling occasion and season, with detection being highest during November to February and earlier in the survey. Mean probability of use for sites was 0.17 ± 0.01 (range = 0.00–0.85) and was influenced by 4 environmental covariates, with the greatest probability of use in areas with gentler slopes, lower elevations, shorter shrubs, and a greater percentage bare ground. We used the most supported model to make a map of predicted habitat use across the Trans‐Pecos region and showed evidence of model fit. Our work provides detailed baseline information on the distribution and environmental relationships of kit fox in the region and can be used to assist with future research and monitoring efforts.

Does water availability shift dietary preferences of coyotes in the west desert of Utah?

Water is one of the most essential resources on the planet and shapes entire ecosystems. Across the western United States, thousands of artificial water sources have been installed to assist wildlife populations in arid environments. It has been reported that kit foxes (Vulpes macrotis) can live independently of free-drinking water, but coyotes (Canis latrans) would have to more than triple their intake of prey biomass to meet energy requirements. However, previous researchers discovered no change in coyote space use, nor were survival rates of coyotes influenced by the removal of water sources. We predicted coyote diets in the treatment areas (i.e., water removed) would show an increase in leporids, as a source of preformed water after the water removal to compensate for the lack of free water. However, we found no evidence of a dietary shift by coyotes towards large-bodied prey (i.e., leporids) after water sources were removed; occurrence of leporids in the coyote diet decreased after water removal in both the control and treatment areas. Based on this study and previous research in Utah's west desert, coyotes in the Great Basin ecosystem were not influenced by artificial water sources in a spatial, demographic, or dietary capacity.

Survey for Select Pathogens in the Desert Kit Fox (Vulpes macrotis arsipus) in California, USA.

Following a canine distemper virus (CDV) epizootic in 2011, serum samples of 45 live-trapped desert kit foxes (Vulpes macrotis arsipus) from the Upper Chuckwalla Valley, California, US, were tested for the presence of antibodies against CDV, canine parvovirus (CPV), canine herpes virus (CHV), canine adenovirus (CAV-2), and Toxoplasma gondii. Fecal swabs were tested by PCR for CPV genomic material, and ocular and nasal swabs were assessed for genomic material of CDV, CHV, CAV-2, influenza virus (H3N8), parainfluenza, canine respiratory coronavirus, Bordetella bronchiseptica, and Streptococcus equi subsp. zooepidemicus. Fourteen foxes (31.1%) were positive in at least one test, with exposure and/or infection confirmed for CDV (6/45, 13.3%), CPV (4/45, 8.9%), S. equi subsp. zooepidemicus (4/45, 8.9%), and T. gondii (2/45, 4.4%). Study results were similar to results reported for kit foxes in other portions of their distribution. Further research with long-term regular testing is needed to understand disease dynamics in kit fox populations better.

Characterization of Salmonella spp. and E. coli Strains Isolated from Wild Carnivores in Janos Biosphere Reserve, Mexico.

Simple SummaryEmerging diseases (EIDs) represent a constant challenge in public health. With the recent emergence of new pathogens, some questions about the mechanisms and sites where they are generated have aroused interest. Natural environments could be the sites where pathogenic microorganisms find the conditions to generate new variants. It has been established that approximately 60.3% of EIDs are caused by potentially zoonotic pathogens, of which more than half are thought to have originated from wild individuals. In this aspect, carnivores can play an important role in the dynamics of various diseases, since there are species that are widely distributed, roam large areas, and can be carriers of a wide range of microorganisms, some of which are zoonotic. The results obtained in this work show that different species of wild carnivores can be carriers of atypical strains of pathogenic microorganisms, which shows that natural environments can represent important sites for the study of EIDs.Enterobacteriaceae are considered one the most important zoonotic pathogens. In this study, we analyzed the characteristics of E. coli and Salmonella spp. strains present in carnivores from Janos Biosphere Reserve, Mexico. These microorganisms had been isolated from a wide range of domestic and free-range animals, including wild carnivores. Fifty-five individuals were sampled, and the presence of Salmonella and E. coli was determined by bacteriological standard methods. Strains isolated were characterized by molecular methods and in vitro infection assays. Eight different species of carnivores were captured, including coyotes (Canis latrans), gray fox (Urocyon cinereoargenteus), desert foxes (Vulpes macrotis), striped skunks (Mephitis mephitis), hooded skunks (Mephitis macroura), lynxes (Lynx rufus), raccoons (Procyon lotor), and badgers (Taxidea taxus). Salmonella spp. and E. coli were isolated from four species of carnivores. Five Salmonella spp. strains were isolated, and their molecular characterization revealed in three of them the presence of fimbrial and virulence genes associated with cell invasion. In vitro evaluation of these strains showed their capability to invade human Hep2 cells. Sixty-one E. coli strains were isolated; different serotypes and phylogroups were observed from these strains. Additionally, the presence of virulence genes showed differently.

Genetic analyses are more sensitive than morphological inspection at detecting the presence of threatened Mojave desert tortoise (Gopherus agassizii) remains in canid scat and raven pellets

AbstractSubsidization of predator populations increases predation pressure on prey species, which is exacerbated when natural resources are scarce. Estimating the frequency of predation by subsidized predators on vulnerable species, especially low‐density, long‐lived species such as the federally threatened Mojave desert tortoise (Gopherus agassizii), allows landscape managers to evaluate the need for actions like reducing subsidies, discouraging predation by taste aversion, or predator removal. Most studies of Mojave desert tortoise predation have relied on morphological analysis to identify hard parts in predator scat. Here, we developed and validated a qPCR assay to test for the presence of Mojave desert tortoise in DNA extracted from scat and pellets. We used the assay to detect tortoise DNA in scat and pellets collected in a conservation easement adjacent to Boulder City, Nevada, from three Mojave desert tortoise predators: coyotes (Canis latrans), desert kit foxes (Vulpes macrotis arsipus), and common ravens (Corvus corax)—all of which consume anthropogenic resources. We compared the results of our qPCR assay to results from morphological analysis of the same samples and found that the qPCR method is much more sensitive at detecting the presence of tortoise remains. Although neither method can determine whether consumption was the result of predation or scavenging, nor how many individual tortoises were consumed, our findings indicate that conservation managers may benefit from focusing efforts on reducing subsidies that attract and support predators and on reducing tortoise mortality from predation.