Finding Bat Roosts along Cliffs: Using Rock Climbing Surveys to Identify Roosting Habitat of Bats

Abstract

When white-nose syndrome arrived in eastern North America, bat colonies declined at an alarming rate and the large-scale mortality events were obvious at caves and mines. However, there is concern that the disease and its impacts will be more difficult to detect in western North America where there are fewer winter roosts with thousands of bats. Thus, documenting and responding to precipitous declines will be more challenging. To allow population-level monitoring, western biologists and land managers need to expand search efforts for colonies. One roosting resource that is under-sampled is cliffs, and although we know bats roost along cliffs, biologists know little about roost-site characteristics or the colonies that reside there. Two methods of identifying bat roosts along cliff systems are to collaborate with rock-climbing citizen scientists who report bat encounters, and another is to conduct rock-climbing surveys for bats. We conducted acoustic surveys, thermal videography, and climber-based surveys along the Front Range of northern Colorado, USA, to find bats and describe their roosting habitat. We climbed 48 routes and located two roosts, and received an additional citizen-science record of a third roost. Bats use cracks that were east facing and approximately 12 m above the ground. Climber-based surveys can locate bats and roosting habitat along cliffs, and identify large colonies to be monitored. Targeting climber-based surveys in areas with recreational-climbing citizen-science records may increase the likelihood of finding bat roosts and bat colonies.