Gray Bat Day Roosts in Concrete Barriers on Bridges during Migration

From 2013–2018 crevices between segments of concrete barriers on the sides of 164 bridges in northern Arkansas were surveyed for bat presence on 1270 occasions and gray bats (Myotis grisescens) were found roosting in 21 bridges. Bats used bridges over streams of all sizes and did not select crevices based on width. Seventy-two bats (62 males, 10 females) were captured alive and two were found dead. Most bats were observed in the spring (62, 84%) with some observations in fall (10, 14%), and two (3%) juvenile males were found in the summer. In 75% of observations, a single gray bat was detected on the bridge. However, there were surveys in which multiple gray bats or gray bats and other species used the same crevice. This research provides a better understanding of the migratory patterns of this federally-endangered species.