Studying interspecific interactions and community composition within carnivore guilds are often difficult to complete and seldom done in North America. Here we used a camera trap database from 2009 to 2010 to describe the carnivore diversity and investigate the temporal niche partitioning of community members within the northern edge of the Sierra of Tamaulipas, México. We detected 15 different species of carnivores including six Felids, three Mephitids, as well as two Canids, Mustelids, and Procyonids each. In our diel activity analysis, we observed significant differences in diel activity between jaguars (Panthera onca) and mesocarnivores including ocelots (Leopardus pardalis), jaguarundis (Puma yagouroundi), and gray foxes (Urocyon cinereoargenteus). Ocelots, gray foxes, and white-nosed coatimundis (Nasua narica) had the highest occupancy rates across the study. Difficulty to understand temporal interactions between bobcats (Lynx rufus), pumas (Puma concolor), margay (Leopardus wiedii), coyote (Canis latrans), badgers (Taxidea taxus), three species of skunks (Mephitis sp; Conepatus sp.; Spilogale sp.), and long–tailed weasel (Neogale frenata) may have been related to habitat use, activity, or reclusive behavior. This study illustrates the ecologically rich Sierra of Tamaulipas holds a diverse carnivore community and there is a need for continued monitoring to further understand the dynamics within this ecosystem.

The Sierra Nevada red fox (SNRF), Vulpes vulpes necator, is a high elevation subspecies restricted to montane habitat in California and Oregon. The Sierra Nevada Distinct Population Segment is federally endangered due to low population numbers and low genetic diversity. Despite their recent listing, little is known about their basic ecology, including diet and niche overlap with other mesocarnivores in their community. To help fill these gaps, we used DNA extracted from 924 mesocarnivore scats collected from the Sonora Pass region of the Sierra Nevada to characterize the diets of sympatric SNRFs, coyotes, bobcats, and martens. We used metabarcoding to amplify DNA from food items using chloroplast (trnL) and mitochondrial (12SV5) gene regions to identify plant and vertebrate diet items, respectively. We analyzed data to assess which prey were likely of greatest importance to SNRFs during different seasons and used Pianka's niche overlap index to quantify diet overlap among SNRFs, coyotes, martens, and bobcats. Our results on key prey species, diet diversity, seasonal differences in diet, and dietary overlap with potential competitors provide basic ecological understanding fundamental to recovery planning.

Thermoregulation is essential yet energetically costly in endotherms, resulting in body temperature fluctuations and biological trade-offs. Advanced biologging technologies allow for continuous, remote monitoring of body temperature in wild animals. We used ruminant implant transmitters (RITs) and GPS collars to examine how desert bighorn sheep (Ovis canadensis nelsoni) thermoregulate and survive in extreme desert conditions. We tracked 43 individuals across six populations in the Mojave Desert of California over a 13-month period—15,342 observation days. RITs logged body temperature and collars recorded ambient temperature—we estimated daily median and variation (heterothermy index, HI) for both. We evaluated seasonal differences between sexes and across populations, and validated collar temperatures with external temperature loggers to assess the effect of ambient temperature on thermoregulation. Desert bighorn body temperature was 38.86°C ± 0.305°C (IQR). Annual HI ranged 0.349—0.617, and individuals with HI > 0.55 had lower survival. Daily HI for both sexes increased with ambient temperature, but male temperatures averaged 0.12°C - 0.21°C cooler than females from July thru October. Our research underscores the critical role of thermoregulation in desert bighorn survival, highlighting sex-specific responses and the impact of ambient temperatures, while demonstrating the potential of biologging to inform wildlife research and conservation. 

Recognizing the critical role of small mammals in forest biodiversity, the study aims to develop efficient monitoring techniques crucial for conservation and management efforts. Addressing two primary objectives, the research compares the effectiveness of three distinct camera-trap survey techniques (ground, tree, and tube) with traditional live trapping methods, and explores the species composition across old- and second-growth forest stands.Results reveal that camera-trap methods outperform live-trap techniques, demonstrating higher small mammal diversity and significantly increased capture rates. Moreover, the study finds that camera-traps are more cost-effective, reducing labor and ethical costs compared to live-trapping. Ten small mammal species were detected, with higher activity recorded in old-growth stands. The tube camera method proved most effective in capturing species richness. This research contributes to a deeper understanding of small mammal ecology in redwood forest ecosystems, supporting informed decision-making for conservation and management strategies in fragmented landscapes. The findings underscore the efficacy and cost-effectiveness of camera-trap techniques, emphasizing their importance in monitoring small mammal populations for effective conservation planning.

Accurate estimates of wildlife population sizes over time allow for more informed conservation of harvested species. Annual harvest data itself can be a valuable source of information for modeling populations, particularly in cases where age information is collected from harvested individuals. Coupled with prior knowledge of a species’ biology, these age-at-harvest (AAH) data can be modeled in an integrated Bayesian framework to estimate population sizes over time. Here, we apply this type of integrated population model (IPM) to AAH data collected from black bears in California over the last decade. We fit our statewide IPM in a hierarchical way to separately estimate black bear demographic rates and population dynamics in different proposed bear management regions (BMRs) by drawing from statewide prior distributions of black bear demography. Additionally, we created a binary annual covariate on survival rate in the hunting season to capture reduced hunting effort due to COVID-19 lockdowns in 2020. Our IPM estimated a stable black bear population of approximately 73,700 (± ~ 15,000) bears in California, with some variation in estimated trends across the different BMRs. The IPM will allow for continued tracking of black bear populations across key areas of California under changing conditions.

Sympatric apex predators utilize different behaviors to reduce competitive or antagonistic interactions. Instances where one species is recovering or colonizing new areas, understanding these interactions is immensely valuable and is critical for assessing potential impacts on management of prey species and apex carnivores. Gray wolves (Canis lupus) began recolonizing California in 2011, expanding their range into the southern Sierra Nevada by 2023. Mountain lions (Puma concolor) and black bears (Ursus americanus) have known antagonistic interactions in Northern California, which can impact local big game populations. Additionally, gray wolves have been shown to negatively affect mountain lion abundance and activity patterns across western North America; however, this is understudied in California. Starting in July 2023, we initiated a multi-year camera study to understand gray wolf interactions with other carnivores across two study areas (58 camera stations) in the Cascade-Siskiyou and northern Sierra Nevada mountain ranges of California. Preliminary data gained from this study will shed light on potential temporal and spatial coexistence or avoidance. The study is projected to double in size across each landscape to assess localized population abundance of mountain lions and wolves, as well as interactions with the larger species guild. Future implications will aid apex carnivore ecology in California.

Planning for wildlife crossings is a critical activity because: 1) location can determine utilization by individual species and 2) once wildlife crossings are built, they are unlikely to be re-located. Despite how critical this aspect of wildlife crossing siting is, there is little guidance for how to scientifically carry out this step. To help develop the scientific basis for this type of conservation action, we developed a spatially-explicit decision-support system (SEDS) that combined various datasets of wildlife occurrence and habitat suitability models. SEDS was based on a series of steps: 1) objective setting by an organization planning wildlife crossings across State route 152 (SR152), the Santa Clara Valley Habitat Agency, 2) collection of data and models describing potential or actual wildlife occurrence; and 3) development of alternative models incorporating habitat, ownership, wildlife occurrence, constructability, and wildlife use of existing structures. These alternatives informed different ways of making crossing decisions, including under- versus over-crossings, duplication of crossings, and inclusion of single or multiple focal species. The SEDS for SR152 resulted in 4 candidate sites for under- or over-crossings which have been advanced to engineering design and environmental permitting. The approach is currently being used for similar wildlife crossing planning for 6 other highways.