Response in Abert's Squirrel Abundance to Forest Treatments on Camp Navajo, Arizona

Abstract

Abert's squirrels (Sciurus aberti) are dependent upon ponderosa pine (Pinus ponderosa) forests in northern Arizona. Abert's squirrels feed primarily on the inner bark of ponderosa pine branches, as well as the tree's seeds and the hypogenous fungi associated with ponderosa pines. Abert's squirrels require interlocking tree canopies for escape cover and for feeding, particularly in winter months when snow impedes ground travel and the ability of Abert's squirrels to access fungi and hoarded food. In the Southwest, land managers in the ponderosa pine belt are implementing large-scale forest restoration treatments to reduce fire risk and return forest structure to pre-European settlement conditions. Restoration may decrease intrastand structural diversity and interstand heterogeneity for several decades, reducing the amount of habitat available to Abert's squirrels and reducing overall abundance. We estimated Abert's squirrel densities by enumerating squirrel feeding sign (branch clippings, clipped cones, truffle digging) over 9 years on 15 sites on Camp Navajo, an Arizona Army National Guard base in northern Arizona. Sites were treated at different times throughout the duration of the study. We evaluated the effects of forest restoration treatments on Abert's squirrel densities. We found no difference in Abert's squirrel densities on sites experiencing different treatment types. However, we did find a difference in Abert's squirrel densities between years.