Multiscale habitat selection of an imperiled subspecies of Least Chipmunk (Neotamias minimus): when a generalist is really a specialist.

Abstract

Habitat loss is a leading cause of species endangerment, yet information about habitat is anecdotal for most mammals. The Least Chipmunk (Neotamias minimus) is the most widespread chipmunk in North America and is purportedly a habitat generalist, which should buffer it against habitat loss. However, the southernmost subspecies (Peñasco Least Chipmunk [N. m. atristriatus]) in the Sacramento Mountains of southern New Mexico has declined significantly and has been proposed for listing as endangered under the Endangered Species Act. The declining subspecies presents a conundrum because it could be either a habitat generalist experiencing declines due to factors other than habitat loss or a habitat specialist experiencing habitat loss. We investigated multiscale habitat selection by N. m. atristriatus at the landscape, home-range, and within-home-range scales. We hypothesized that habitat selection by the Peñasco Least Chipmunk would be influenced by plant community type, topography, disturbance, ecological edge, and understory structure. For the landscape scale we conducted surveys using remote cameras and tested predictions using occupancy models. At the home-range and within-home-range scales, we obtained used locations via radiotelemetry and tested predictions by comparing habitat features at used and available locations. At all 3 scales, chipmunks selected for open stands of relatively large trees interspersed with meadows containing low cover provided by shrubs. This specialized vegetation structure was principally provided by a distinctive Engelmann Spruce (Picea engelmannii)-Gooseberry Currant (Ribes montigenum) plant community. Chipmunks avoided disturbance including burnt forests, ski runs, and roads. We conclude that the Peñasco Least Chipmunk is a habitat specialist across multiple scales and that the loss of its required habitat has been the principal cause of its decline.