Social behavior of the little brown bat, Myotis lucifugus
We studied the social and mating behavior of Myotis lucifugus at two hibernacula (Renfrew Mine and Tyendinaga Cave) in Ontario during the swarming and hibernation periods of 1976 and 1977.
During July the population of bats arriving at the hibernacula consisted of adult males and nulliparous females, while in August and September subadults and post-partum females predominated.
Inside the hibernacula bats often flew in pairs consisting of adult males following females, and transient groups of females and subadult males formed around adult males.
Mating began in late August and had two behaviourally distinct phases. Prior to the build-up of torpid females in the hibernacula, copulations followed both paired flying associations and interactions in groups. After torpid females became common, addult males often forced copulations with torpid bats of either sex.
Adult males showed no site fidelity or competition for females.
The mating system is described as indiscriminate and promiscuous, and the factors determining its structure are discussed.