Yosemite Cougar Project

The cougar is the most widely distributed wild mammal in the western hemisphere and occurs in a variety of biomes. Despite their widespread distribution, cougars can be difficult to study at broad geographic scales because they exhibit large home ranges, wide-ranging movement patterns, and low population densities. Thus, little is empirically known about the abundance or density of cougars in remote and less-developed areas, and whether these areas might support higher cougar densities than developed or fragmented landscapes.

In the Sierra Nevada of California, cougars are thought to be declining and occur within and interact with a diverse ecological community that includes a suite of other species of conservation interest. Clarifying the density and distribution of cougars, including how landscape structure influences their occurrence, may both inform their conservation and mitigate potential negative effects on other species of conservation concern.

We collaborated closely with Yosemite National Park, Rogue Detection Teams, and the Mammalian Ecology and Conservation Unit at the University of California Davis to estimate the abundance, density, and distribution of cougars in Yosemite National Park. We modeled spatial encounter data collected in 2019 and 2020 from DNA-based individual identification of scats with detection count data derived from remote cameras to estimate cougar density and detection probability.

We estimated there to be 31 cougars in Yosemite, with higher densities associated with productive, vegetated areas. We found detection probability by scent detection teams was higher for females than males and positively correlated with survey effort, proximity to trails, and distance farther from roads and streams. Our study illustrates the utility of noninvasive survey methods that yield individual identities in rugged and remote environments, where capture and handling of cryptic, low-density animals is logistically challenging and cost prohibitive (Martin et al. In Press).