Occupancy and Habitat Associations of Four Species of Sciurids in Ponderosa Pine-Gambel Oak (Pinus ponderosa-Quercus gambelii) Forests in Northern Arizona

Abstract

In ponderosa pine-Gambel oak (Pinus ponderosa-Quercus gambelii) forests of north-central Arizona, we examined occupancy and habitats of four species of sciurids (rock squirrel Spermophilus variegatus, golden-mantled ground squirrel S. lateralis, gray-collared chipmunk Tamias cinereicollis, cliff chipmunk T. dorsalis). Numbers of captures were highly variable, suggesting a patchy distribution of species. All four species co-occurred on only one of the study sites. Gray-collared chipmunks and golden-mantled ground squirrels were relatively common on one site only. Golden-mantled ground squirrels were associated with mature forests with high canopy cover and low basal area, whereas gray-collared chipmunks were in locations with large numbers of logs and shallow litter. The two species of chipmunks appeared to be separated in space; gray-collared chipmunks were more common where cliff chipmunks were least common. Rock squirrels were relatively ubiquitous. There was evidence for an association of rock squirrels with increasing rocky cover and decreasing canopy cover, whereas cliff chipmunks occupied rocky areas with high canopy cover and numerous shrubs.