Movement and habitat selection of the western spadefoot (Spea hammondii) in southern California

Abstract/Summary

Agricultural activity, urban development and habitat alteration have caused the disappearance of the western spadefoot (Spea hammondii) from 80% of its range in southern California. Despite the western spadefoot’s continuing decline, little research has been conducted on its natural history. The home range of adult spadefoot is unknown, and their use of upland habitat is poorly understood. Both of these factors are important for the long-term conservation of the species because adult spadefoot spend the majority of their lives away from breeding pools. During the course of this study, radio transmitters were surgically implanted in 15 spadefoot and their movements and habitat use recorded for an average of 272 days. During that time, rain was the only significant predictor of spadefoot movement. The overall mean distance moved between burrow sites was https://17.56 m (SD ± https://23.96 m, N = 184). The mean distance moved away from the breeding pools was https://40.04 m (SD ± https://37.42, N = 200). The maximum distance moved away from the breeding pools was https://261.99 m. The amount of clay was the only predictor of spadefoot burrow locations, with spadefoot burrowing in friable soil with significantly less clay than random non-spadefoot sites. This study enhances our understanding of a little-studied species and will assist land managers in the formation of effective management plans for the spadefoot.