Wildland Resources Faculty Publications

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 (βinteraction = 0.30 ± 1.1), nor did the removal influence home range size (βinteraction = 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.

As the most widespread large carnivore on the planet, domestic dogs Canis lupus familiaris can pose a major threat to wildlife, even within protected areas (PAs). Growing human presence in PAs, coupled with increasing pet dog ownership underscores the urgency to understand the influence of dogs on wildlife activity and health. This knowledge can mitigate the adverse repercussions of recreation, optimizing PA management. Drawing on five years (2017–2021) of data from 101 camera traps in the San Francisco Bay Area, California, United States, we measured the spatiotemporal responses of puma Puma concolor, bobcat Lynx rufus, coyote Canis latrans, and mule deer Odocoileus hemionus towards domestic dogs. Additionally, using six years (2017–2022) of community science data, we explored the impacts of PA dog policies on puma sightings outside park boundaries. Puma responses provide insights into broader ecological impacts, while analyses of bobcat, coyote, and mule deer offer a comprehensive understanding of species responses to dog-friendly spaces. Because dogs can be perceived as predators or competitors by wildlife, we anticipated shifts in spatial and temporal activity patterns in response to dogs. Wildlife responses included avoidance (bobcat, puma) or spatial overlap (mule deer) for areas with more dogs, and no effect (coyote). Mule deer may benefit from a "human shield" provided by people with dogs, while pumas and bobcats appeared more sensitive, and coyotes more adaptable. Dog policies influenced puma and mule deer temporal activity, with increased nocturnal activity in dog-friendly PAs. Bobcat temporal activity was less variable in dog-friendly PAs and coyote activity was similar between treatments. Outside PAs, puma sightings increased with human disturbance. Our study underscores the trade-offs between recreation and wildlife conservation, emphasizing the need to quantify the ecological impacts of dogs. This understanding is vital for informing conservation strategies and promoting coexistence between dogs, wildlife, and protected environments.

Results of research in forest health and forest futures in Utah

Results of research in forest health and forest futures in Utah

Results of research in forest health and forest futures in Utah