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Nonrandom patterns of roost emergence in big brown bats, Eptesicus fuscus

January 1, 2011

In most colonial species of bats individuals emerge en masse from day roosts each evening to begin foraging. Although some aspects of emergence behavior are understood, one previously unexplored area is the specific order in which individuals emerge. The goal of our research was to determine if big brown bats, Eptesicus fuscus, fitted with passive integrated transponder tags emerge from roosts in buildings each evening in a nonrandom order. We assessed relative and absolute order of emergence to determine if order is concordant across nights and whether individuals consistently emerge in close association with specific roost mates. We found significant concordance in rank order among nights at all roosts. At 5 roosts concordance decreased as time between dates increased. Association rates between individuals were low, and temporal analyses revealed that associations rapidly degraded over time, indicating that bats do not emerge each evening consistently with the same group of roost mates. We discuss how social structure, information transfer, and/or individual energetic needs could be responsible for the observed nonrandom patterns of emergence. Our results suggest that emergence order represents behavioral information that traditionally has been overlooked and that might be useful for characterizing aspects of the ecology and social behavior of bats and other species with cryptic behavior.

Publication Year 2011
Title Nonrandom patterns of roost emergence in big brown bats, Eptesicus fuscus
DOI 10.1644/10-MAMM-A-393.1
Authors E.H. Gillam, Thomas J. O'Shea, R.M. Brigham
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Mammalogy
Index ID 70035589
Record Source USGS Publications Warehouse