Den Site Selection by the Rock Squirrel (Spermophilus variegatus) in Southeastern Arizona

Abstract

Physical and vegetational characteristics of rock squirrel ( Spermophilus variegatus ) den sites were investigated during 1983, 1984, and 1985 at the National Audubon Society's Appleton-Whittell Biological Research Sanctuary in southeastern Arizona. Relative to habitat availability, rock squirrel den sites occurred in greater than expected frequencies in oak savanna and riparian habitats. A comparison between 56 den sites and 40 control locations in rock squirrel-occupied habitat revealed significant differences ( P ≤ 0.002) for 12 (52.2%) of 23 physical and vegetational variables. Compared to control locations, dens were located 1) on steeper slopes, 2) in shadier sites, 3) closer to oaks, Quercus spp., 4) closer to washes, 5) associated with prominent potential lookout points, 6) in areas with less ground cover, and 7) associated to a lesser degree with more northerly facing slopes. Discriminant function analysis correctly classified 81.3% of den locations and control sites using only two variables, percent shade and angle of slope.