Translocation as a Nonlethal Alternative for Managing California Ground Squirrels

Abstract

To evaluate the efficacy of translocation as a nonlethal management alternative, we determined trapability, post-release survival, site fidelity, and homing ability of experimentally translocated California ground squirrels (Spermophilus beecheyi). Trapability of squirrels was low (0.04 captures/trap-day). Most squirrels (71-79%) survived until ≥18 days after translocation; mortality was highest shortly after release, and was attributed mostly to predation. Of those squirrels that survived but did not return home, 85% established a new home range, but most settled away from the release site. Homing success decreased with translocation distance. Our data do not support the hypothesis that homing results from navigation, but they do support the hypothesis that homing results from piloting when squirrels are inside their area of familiarity, perhaps extended by visual detection of distant landmarks, and random search when outside. Translocation probably is infeasible for control of squirrels over large areas because of low trapability, but shows potential for smaller localities. Squirrels, however, must be translocated far enough (ca. 1,500 m) to prevent homing, and lack of fidelity to the release site may result in squirrels settling in undesirable locations.