Bat Colonies in Buildings


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Monitoring Trends in Bat Populations of the United States and Territories: Problems and Prospects

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Bats use buildings as maternity roosts, night roosts, bachelor roosts, transient roosts, and occasionally as hibernacula. Of the 46 species of bats known from North America north of Mexico, over half are known to use buildings as roosts at least for part of the year. Use of human-made structures is a consequence of the loss of natural shelters that no longer exist and occurs wherever bats and humans co-exist. Nonetheless, the few available data suggest that the number of colonies in buildings is declining and that persistence is limited by deterioration of structures and attempts by residents to exclude bats. In North America, big brown bats (Eptesicus fuscus), little brown bats (Myotis lucifugus), eastern pipistrelles (Pipistrellus subflavus), and Brazilian free-tailed bats (Tadarida brasiliensis) are the best-known species that roost in buildings. All form maternity colonies in buildings during the summer. Efforts to census bats in buildings pose several challenges. Evening emergence counts provide the most reliable estimates, especially where colonies consist of less than 1,000 individuals. Such counts should be made on at least three consecutive evenings in the period of late pregnancy to mid-lactation, which generally corresponds to the maximum adult population. With continued loss of natural habitats, bat houses offer opportunities for bat conservation as well as platforms for research on aspects of bat biology that are difficult or impossible to study in natural roosts.


Novel Bat, Coronaviruses, Brazil, Mexico

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