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Remote 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. [ABSTRACT FROM AUTHOR]

Golden eagles Aquila chrysaetos are a long‐lived and wide‐ranging species believed to be stable or in slight decline across North America. Golden eagles have an extended subadult stage (4–5 years) that is critical to maintaining recruitment into the breeding population and population viability. Compared to adult golden eagles, the ecology of subadult golden eagles (hereafter, subadults) has received little attention. We investigated patterns of resource selection for subadults in the Great Basin Desert of the western United States during summer and winter, 2013–2019. We monitored 46 subadults with GPS transmitters and related locations (n = 99 037) with predictors hypothesized to influence seasonal patterns of space use with mixed‐effects logistic regression. Subadults selected for ridges and upper slopes in summer and winter, but higher elevations in summer. Subadults showed weak selection for lower ridge density in summer, which was likely facilitated by selection for areas with greater thermal wind current potential. In contrast, subadults showed strong selection for higher ridge density in winter. Subadults selected areas further from roads in summer and closer to roads and electrical transmission lines in winter, which may be related to winter scavenging of road‐killed ungulates. Resource selection functions suggested subadults selected for shrublands and woodlands in both seasons, but odds ratios revealed that during winter subadults avoided shrublands and increased selection of woodlands relative to summer. Subadults selected for areas with infrequent fires in both seasons; areas with frequent fires were avoided in summer but selected for in winter. Seasonal changes in resource selection suggested that subadults used woodlands more than expected, potentially reflecting spatial partitioning by subadults to lower‐quality habitats to minimize competition with breeding adults during winter when energetic demands for thermoregulation were presumably higher and prey more limited. [ABSTRACT FROM AUTHOR]

Free water can influence the ecology of desert species. While the use of free water is influenced by physiological factors (e.g., species‐specific water requirements, moisture in forage, temperature), nonphysiological factors, such as habitat characteristics and interspecific interactions, are also important. In fact, for species of concern, interspecific interactions and habitat can be important factors influencing their spatial and temporal use of the landscape and its resources. The kit fox (Vulpes macrotis) is a small carnivore considered to be a species of concern over much of its range, and two of the most important conservation challenges it faces are related to (1) habitat and (2) predation/competition by intraguild species. Our objective was to determine the influence of habitat characteristics, predators (bobcats [Lynx rufus], coyotes [Canis latrans]), and potential competitors (badgers [Taxidea taxus], gray foxes [Urocyon cinereoargenteus]) on the use of water by kit foxes. From June to September 2010–2012, we used remote cameras to monitor carnivores at 63 water sources in the Mojave Desert. We used zero‐inflated mixed‐effects models and a two‐stage model selection analysis to evaluate the influence of habitat, predators, and competitors on spatial visits to water by kit foxes. We also assessed temporal avoidance of intraguild predators and competitors by kit foxes at water sources using a coefficient of overlap. We found that visual obscurity, overhead canopy cover, badgers, and coyotes influenced spatial visits of kit foxes. In addition, kit foxes exhibited strong temporal overlap with badgers and bobcats, moderate temporal overlap with gray foxes, and weak temporal overlap with coyotes. Taken together, our study demonstrates that the spatial and temporal use of water sources by kit foxes is dynamic, depending on habitat characteristics and the activity of intraguild predators and competitors. [ABSTRACT FROM AUTHOR]

The kit fox Vulpes macrotis is a species of concern to land managers in the Great Basin Desert of North America. Once common, kit foxes have declined from historical levels. Research on kit foxes in western Utah has spanned nearly 70 y and has potential to inform management and conservation within the Central Basin and Range Ecoregion of the Great Basin Desert. We conducted a systematic literature review on the northern kit fox subspecies V. m. nevadensis. We focused on studies conducted in the Central Basin and Range Ecoregion, which represents the majority of the Great Basin Desert, and provided a comprehensive summary of their ecology and demographics for resource managers. To guide future monitoring, we also reviewed techniques used for kit fox monitoring and research, and evaluated the strengths, limitations, and advances of these techniques. We identified four key factors that deserve consideration when selecting monitoring techniques for kit foxes: estimable parameters, reliability, cost, and rate of data return. Finally, we identify four primary management recommendations. We recommend that managers (1) expand kit fox monitoring and population assessments more broadly across the Great Basin Desert. To ensure future monitoring meets the needs of resource managers, we recommend (2) the application of a structured decision-making process to identify key parameters and approaches. To better understand the factors limiting kit fox populations we recommend (3) population viability and parameter sensitivity analyses to identify drivers of population change. Finally, based on evidence that genetic diversity of kit fox populations has been maintained by undescribed patterns of gene flow, we recommend (4) a broad-scale assessment of population connectivity to identify corridors supporting metapopulation dynamics. These recommendations will facilitate proactive conservation of kit foxes and management practices to reduce future population declines. [ABSTRACT FROM AUTHOR]

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Eared Grebes ( Podiceps nigricollis) staging at the Great Salt Lake, Utah, USA, sometimes experience weather-induced downings where many individuals are killed. Downings of Eared Grebes moving south during the fall have been reported for decades; however, spring downings are rare and underrepresented in the literature. On 15 April 2013, 13,500 Eared Grebes flying northward encountered inclement weather, were attracted to lights on Dugway Proving Ground, and downed. This spring downing was documented, and population characteristics were compared with those observed in previous downings. An estimated 38% were killed outright. Rescue efforts promoted the survival of 88% of those not killed on impact. Grebes that were 9-10 months old were, on average, 10% lighter than adults in the same flight, perhaps indicating slow growth or age differences in foraging efficiency. Adults dominated all downings, supporting previous information that adults and young migrate on different schedules. The sex ratio in the North American population appears to be 1:1. Downings occur when Eared Grebes encounter inclement weather and are attracted to lights. Knowledge of the route, migration period, and flight speed of Eared Grebes allows predictions about when and where downings are likely to occur. Reducing the number and intensity of lights on snowy nights in high risk areas may decrease mortality. [ABSTRACT FROM AUTHOR]

Scat surveys are commonly used to monitor wildlife populations. For carnivores, surveys are typically conducted along roads and trails. Scats available for detection may not reflect scats deposited and variation in disappearance may bias results. Previous research has investigated natural decay and deterioration, but scats deposited along roads or trails are likely influenced to a greater degree by anthropogenic disturbance in some systems. We used experimental plots to evaluate variation in scat removal for two model carnivores, coyote Canis latrans and kit fox Vulpes macrotis, along roads in the Great Basin Desert, USA. Using parametric survival regression, we predicted scat survival and developed persistence-rate correction factors, which were applied to results from relative abundance scat surveys conducted along 15 transects. Kit fox scats disappeared more rapidly than coyote scats, with 3.3% and 10.6%, respectively, persisting through 42 days. At 14 days, 90.8-41.7% of scats had been removed across road types. Survival models indicated species, road type, scat position and daily traffic were important predictors of scat persistence. Applying persistence-rate correction factors to scat survey results altered the inferred relative abundances. Across seasons, mean corrected:uncorrected relative abundance ratios ranged from 1.0-91.2 for coyotes and 1.3-139.3 for kit foxes, with higher mean ratios being influenced by high corrected relative abundances on roads with high traffic volumes. Understanding scat removal rates and patterns can improve inferences from surveys. Persistence-rate correction factors can be used to reduce bias in indices of abundance, but caution should be used when removal rates are high. Knowledge of spatial variation in persistence can elucidate concerns of false-positives and false-negatives in occupancy and capture-recapture studies. Considering the disparity in scat removal between species and among road types and positions, we recommend practitioners quantify and consider variation in removal when interpreting scat survey results. [ABSTRACT FROM AUTHOR]

Exotic invasive species can directly and indirectly influence natural ecological communities. Cheatgrass (Bromus tectorum) is non-native to the western United States and has invaded large areas of the Great Basin. Changes to the structure and composition of plant communities invaded by cheatgrass likely have effects at higher trophic levels. As a keystone guild in North American deserts, granivorous small mammals drive and maintain plant diversity. Our objective was to assess potential effects of invasion by cheatgrass on small-mammal communities. We sampled small-mammal and plant communities at 70 sites (Great Basin, Utah). We assessed abundance and diversity of the small-mammal community, diversity of the plant community, and the percentage of cheatgrass cover and shrub species. Abundance and diversity of the small-mammal community decreased with increasing abundance of cheatgrass. Similarly, cover of cheatgrass remained a significant predictor of small-mammal abundance even after accounting for the loss of the shrub layer and plant diversity, suggesting that there are direct and indirect effects of cheatgrass. The change in the small-mammal communities associated with invasion of cheatgrass likely has effects through higher and lower trophic levels and has the potential to cause major changes in ecosystem structure and function. [ABSTRACT FROM AUTHOR]

Anthropogenic modifications to landscapes intended to benefit wildlife may negatively influence wildlife communities. Anthropogenic provisioning of free water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence native species. Water developments may negatively influence arid-adapted species (e.g., kit fox, Vulpes macrotis) by enabling water-dependent competitors (e.g., coyote, Canis latrans) to expand distribution in arid landscapes (i.e., indirect effect of water hypothesis). We tested the two predictions of the indirect effect of water hypothesis (i.e., coyotes will visit areas with free water more frequently and kit foxes will spatially and temporally avoid coyotes) and evaluated relative use of free water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet) and without (dry) free water and monitored visitation by canids to these sites and visitation to water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. We did not detect spatial (no negative correlation between visits to scent stations) or temporal (no difference between times when stations were visited) segregation between coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. Our results did not support the indirect effect of water hypothesis in the Great Basin or Mojave Deserts for these two canids. [ABSTRACT FROM AUTHOR]

Monitoring mammalian carnivores at den sites with human observers to document behavior, fecundity, litter size, and natal survival is commonplace when compared with monitoring den sites with cameras. However, no published studies exist comparing the effectiveness of human observers versus cameras in a quantitative manner. Obtaining complete and reliable counts of adult and pup kit foxes ( Vulpes macrotis) can be crucial for estimating population parameters and life-history traits. In the summers of 2010 and 2011, we made weekly counts of adult and pup kit foxes at active den sites using 2 methods: 1) an observer equipped with spotting scope and/or binoculars and 2) a remote infrared motion-sensitive camera. We accumulated 71 and 29 counts at active den sites, respectively. The median number of adults observed at den sites with a camera and observer differed and were 2 adults versus 1 adult, respectively. Similarly, the median number of pups observed at den sites with a remote camera versus an observer differed and was 2 pups versus 1 pup, respectively. We observed these differences despite the similar effort required to manage cameras and conduct observations. We recommend future surveys aimed at ascertaining more reliable counts of kit foxes and similar species at den sites use a survey methodology employing remote cameras or video over a multi-day period. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]

In 1953, investigators at the Rocky Mountain Laboratories in Hamilton, MT, described the isolation of a spotted fever group Rickettsia (SFGR) species from Dermacentor parumapertus ticks collected from black-tailed jackrabbits (Lepus californicus) in northern Nevada. Several decades later, investigators characterized this SFGR (designated the parumapertus agent) by using mouse serotyping methods and determined that it represented a distinct rickettsial serotype closely related to Rickettsia parkeri; nonetheless, the parumapertus agent was not further characterized or studied. To our knowledge, no isolates of the parumapertus agent remain in any rickettsial culture collection, which precludes contemporary phylogenetic placement of this enigmatic SFGR. To rediscover the parumapertus agent, adult-stage D. parumapertus ticks were collected from black-tailed jackrabbits shot or encountered as roadkills in Arizona, Utah, or Texas from 2011 to 2016. A total of 339 ticks were collected and evaluated for infection with Rickettsia species. Of 112 D. parumapertus ticks collected in south Texas, 16 (14.3%) contained partial ompA sequences with the closest identity (99.6%) to Rickettsia sp. strain Atlantic rainforest Aa46, an SFGR that is closely related or identical to an SFGR species that causes a mild rickettsiosis in several states of Brazil. A pure isolate, designated strain Black Gap, was cultivated in Vero E6 cells, and sequence analysis of the rrs, gltA, sca0, sca5, and sca4 genes also revealed the closest genetic identity to Rickettsia sp. Atlantic rainforest Aa46. Phylogenetic analysis of the five concatenated rickettsial genes place Rickettsia sp. strain Black Gap and Rickettsia sp. Atlantic rainforest Aa46 with R. parkeri in a distinct and well-supported clade. IMPORTANCE We suggest that Rickettsia sp. Black Gap and Rickettsia sp. Atlantic rainforest Aa46 represent nearly identical strains of R. parkeri and that Rickettsia sp. Black Gap or a very similar strain of R. parkeri represents the parumapertus agent. The close genetic relatedness among these taxa, as well as the response of guinea pigs infected with the Black Gap strain, suggests that R. parkeri Black Gap could cause disease in humans. The identification of this organism could also account, at least in part, for the remarkable differences in severity ascribed to Rocky Mountain spotted fever (RMSF) among various regions of the American West during the early 20th century. We suggest that the wide variation in case fatality rates attributed to RMSF could have occurred by the inadvertent inclusion of cases of milder disease caused by R. parkeri Black Gap. [ABSTRACT FROM AUTHOR]

Abstract: Animals that are potential prey do not respond equally to direct and indirect cues related to risk of predation. Based on differential responses to cues, three hypotheses have been proposed to explain spatial variation in vigilance behavior. The predator-vigilance hypothesis proposes that prey increase vigilance where there is evidence of predators. The visibility-vigilance hypothesis suggests that prey increase vigilance where visibility is obstructed. Alternatively, the refuge-vigilance hypothesis proposes that prey may perceive areas with low visibility (greater cover) as refuges and decrease vigilance. We evaluated support for these hypotheses using the kit fox (Vulpes macrotis), a solitary carnivore subject to intraguild predation, as a model. From 2010 to 2012, we used infrared-triggered cameras to record video of kit fox behavior at water sources in Utah, USA. The refuge-vigilance hypothesis explained more variation in vigilance behavior of kit foxes than the other two hypotheses (AICc model weight=0.37). Kit foxes were less vigilant at water sources with low overhead cover (refuge) obstructing visibility. Based on our results, the predator-vigilance and visibility-vigilance hypotheses may not be applicable to all species of prey. Solitary prey, unlike gregarious prey, may use areas with concealing cover to maximize resource acquisition and minimize vigilance. [Copyright &y& Elsevier]