Freeze-branding to permanently mark bats

Abstract

We tested the effectiveness of freeze-branding as a permanent marking technique on 4 species of bats: Brazilian free-tailed bat (Tadarida brasiliensis), Townsend's big-eared bat (Corynorhinus townsendii), big brown bat (Eptesicus fuscus), and western small-footed myotis (Myotis ciliolabrum). Small copper branding irons (9.3 g and 15.6 g) were cooled in a mixture of dry ice and ethyl alcohol and applied to the dorsal skin for varying lengths of time (range=1.5-7.0 seconds). Branding was successful for all species when applied with brand temperatures ranging from -56.7° to -67.7°C. Branded areas grew white hair in an average of 36 days (range=22-60 days). Branded bats were identified easily while roosting, thus eliminating the need to handle them to identify individuals. No adverse effects were observed during or after branding. Results of this study indicate that freeze-branding is a safe and effective method to permanently mark bats.