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Dryad

Seasonal variation in age, sex, and reproductive status of Mexican free-tailed bats

Data files

Sep 28, 2021 version files 1.69 MB
Nov 18, 2021 version files 1.69 MB
Feb 08, 2022 version files 1.69 MB

Abstract

In North America, Mexican free-tailed bats (Tadarida brasiliensis mexicana) consume vast numbers of insects contributing to the economic well-being of society. Mexican free-tailed bats have declined due to historic guano mining, roost destruction, and bioaccumulation of organochlorine pesticides. Long-distance migrations and dense congregations at roosts exacerbate these declines. Wind energy development further threatens bat communities worldwide and presents emerging challenges to bat conservation. Effective mitigation of bat mortality at wind energy facilities requires baseline data on the biology of affected populations. We collected data on age, sex, and reproductive condition of Mexican free-tailed bats at a cave roost in eastern Nevada located six km from a 152-megawatt industrial wind energy facility. Over five years, we captured 46,353 Mexican free-tailed bats. Although just over half of the caught individuals were non-reproductive adult males (53.6%), 826 pregnant, 892 lactating, 10,101 post-lactating, and 4,327 non-reproductive adult females were captured. Juveniles comprised 11.5% of captures. Female reproductive phenology was delayed relative to conspecific roosts at lower latitudes, likely due to cooler temperatures. Roost use by reproductive females and juvenile bats demonstrates this site is a maternity roost, with significant ecological and conservation value. To our knowledge, no other industrial scale wind energy facilities exist in such close proximity to a heavily used bat roost in North America. Given the susceptibility of Mexican free-tailed bats to wind turbine mortality and the proximity of this roost to a wind energy facility, these data provide a foundation from which differential impacts on demographic groups can be assessed.