Locations of black bear (Ursus americanus) reproduction in Nevada from camera-trap data

Understanding factors creating species range boundaries is a fundamental goal of ecology and biogeography. American black bears recolonized the western Great Basin from the Sierra Nevada in the late 1900s but this expansion has not proceeded further into the Great Basin despite the presence of suitable habitat. We deployed 100 camera traps across the occupied range of black bears in the U.S. state of Nevada and tracked bear detections across 3 years. A scent lure was applied in camera trap viewsheds to increase bear detections. We classified detections of bear cubs separately from detections of only adult bears, to serve as an indicator of black bear reproduction occurring at sites. Data are provided in the format necessary for a analysis with multistate occupancy model. Analysis of these data revealed low incidence of reproduction at the periphery of black bear range in the western Great Basin, which likely contributes to range boundary formation.

Methods
Data was collected with camera traps at 100 locations in Northwestern Nevada, spaced approximately 7 km apart. A scent lure was applied in the viewshed of the camera to increase the detection of black bears. Black bear detections were grouped into 30-day periods that indicated whether black bears were or were not detected at a site during a given time period. We separated out cub detections as indicators of black bears reproducing in the vicinity of a site. The black bear hibernation period (Dec-Feb) was excluded from detection histories. Locations were surveyed for 3 years (2018-2020).