Identification and characterization of swarming sites used by bats in Nova Scotia

Abstract

For insectivorous bats living in temperate areas such as Nova Scotia, underground sites are a critical resource for over-wintering, as well as for swarming in the late summer and early fall, which is when mating occurs. The objectives of this study were to 1) identify additional abandoned mines and caves in Nova Scotia that are important swarming sites, and 2) quantitatively characterize factors which best differentiate between caves and mines that are used for swarming/hibernating, and those that are not. Acoustic and/or trapping surveys of 17 abandoned mines and nine caves in Nova Scotia were conducted in 2010. Five site characteristics were analysed to explain differences between used and unused sites. Surveys indicated that twelve of the 26 sites are used by bats during the swarming period. Results of a logistic regression analysis of nine a priori selected models indicated that chamber length was the best predictor of swarming.