Efficacy of scent-detection dogs for locating bat roosts in trees and snags

Abstract

Conservation efforts for tree- and snag-roosting bats are challenging because roost sites are difficult and costly to locate. We assessed the ability of scent detection dogs to locate bat roosts using controlled field experiments conducted at 2 sites in northern Arizona, USA, during July and August of 2007, with small bags of bat guano and known bat roosts. Scent detection dogs correctly detected 79% of guano bags and 29% of known bat roosts; but, when searching during shorter time periods for roosts only, dogs correctly detected 77% of known roosts. Factors affecting detection of guano bags included bag height and mass. Factors affecting detection of roosts included height, size of the bat colony, and air temperature. Rest breaks and competition between dogs apparently increased their success rate in finding roosts. Using a scent detection dog to locate roosts was similar in cost to radiotelemetry; however, the use of a scent detection dog was less invasive because the use of dogs precluded the need to capture and radiotag bats. Important considerations influencing the efficacy of using scent detection dogs include training and transportation costs, and skill level of dog handlers. Although some factors limit the ability of scent detection dogs to accurately locate roosts, dogs in our study approximated the roost location to within a 30-m radius, which may be sufficient to protect these areas during management activities. If managers have the ability within an area to retain all large-diameter snags that have bat roost characteristics, then scent detection dogs will likely not provide adequate added value to warrant their survey costs. However, scent dogs could be important for locating roosts of species that are imperiled or of conservation concern. © 2015 The Wildlife Society.