Effects of human-altered landscapes on a reintroduced ungulate: Patterns of habitat selection at the rangeland-wildland interface

Abstract

Successful species reintroductions require land managers to balance the goal of viable wildlife populations with potential risks to human enterprise. Such risks are particularly acute at the wildland-agriculture interface, where native and domestic species are likely to come into contact. In a national park in northern California, we combined insights from three lines of evidence – long-term visual surveys, short-term GPS telemetry, and satellite remote sensing-based animal detections – to characterize spatial overlap between reintroduced tule elk (Cervus canadensis nannodes) and domestic cattle and to estimate the importance of multiple environmental features as predictors of habitat selection by elk. Our results indicate that, at large spatial scales (i.e., home-range level), cattle were the primary driver of habitat selection, with the occurrence of elk being negatively associated with cattle across all seasons. In addition, elk consistently selected for grasslands on gentle, south-facing slopes that occurred at high elevation and close to ponds. NDVI was a seasonally important, positive predictor of habitat selection, with a marked reversal when this resource was concentrated inside of fenced cow pastures during the dry summer months. By contrast, a novel analysis of satellite-derived animal locations yielded no evidence of avoidance of cattle by elk (within pasture areas commonly used by elk), indicating that this population has acclimated to the presence of cattle through spatial partitioning of resources. Thus, this once-imperiled native ungulate exhibits patterns of habitat selection that reduce the potential for grazing conflicts with cattle, even in cases where access to forage is limited.