PILOT STUDY FOR USE OF SCENT-DETECTION DOGS IN SURVEYS FOR THE GIANT GARTER SNAKE (THAMNOPHIS GIGAS)

Katherine Ayres; H. T. Harvey & Associates; kayres@harveyecology.com; Alexandra L. Thiel, Monica J. Hemenez, Lauralea Oliver, Eric Hansen, Robyn M. Powers

The giant garter snake (GGS) (Thamnophis gigas) is federally and State listed as a threatened species endemic to California's Central Valley. GGS require wetlands for foraging, upland areas for basking, upland refugia as summer shelter, and higher-elevation refugia for winter brumation. Visually, the GGS is elusive: these snakes frequently occur in low-density populations in which individuals are difficult to detect. Detection challenges have resulted in a poor understanding of occupancy patterns throughout much of the species' range, particularly in upland habitat. H. T. Harvey & Associates tested the efficacy of using scent-detection dogs to recognize and alert to GGS residual scent and distinguish it from the scent of sympatric garter snake species. We determined the probability of GGS scent detection and calculated a detection error rate for three dog-handler teams, and determined the change in probability of GGS residual scent detection as scent degraded over a period of six months. The use of scent-detection dogs may offer an efficient and innovative survey approach enabling the detection of GGS both above-ground and in upland refugia.

Ecology and Conservation of Amphibians and Reptiles