White Mountain Research Center

06 Feb, 12 PM - 11 Feb, 09 AM

Hibernating bats exhibit sex differences in energy storage and utilization. Female bats are “thrifty”3, entering hibernation with greater fat deposition than males. They use these reserves more slowly and express shorter bouts of periodic, energetically expensive arousal4. Sex differences also occur in altitudinal migration, in which male and female bats occupy different elevations across seasons. Females tend to migrate up in elevation to hibernate then downhill in spring/summer months, while males tend to remain at lower elevations year round5. This pattern may be explained by the torpor optimization hypothesis which predicts that female bats are under selective pressure to emerge from hibernation with energetic stores remaining to support seasonally-delayed reproduction and increase potential for rapid offspring growth4. It is unknown whether unmated female bats, lacking the need to be energetically prepared for reproductive activity after hibernation, manage energetic stores over winter differently from mated females. To assess the specific profile of energetic stores and mobilization in Towsend’s Big-eared Bats (Corynorhinus townsendii), non-terminal blood and fat tissue samples will be collected from female bats (n=8) at three time points over the hibernation period (early, mid-, and late hibernation). At each these time points, five known hibernacula sites along an elevational gradient (4500, 6000, 7500, 9000, and 10,000ft) will be sampled under existing permit (M.L. Morrison). Upon capture, individual bats will be assessed for prior mating by lavage (flushing) of the reproductive tract to check for spermatozoa. Blood will be collected via brachial venipuncture, using sterile 26 gauge needles, into heparinized capillary tubes. Blood plasma will be used for measurement of circulating leptin, glucose, lipids, and saturated vs. unsaturated fatty acids. Adipose tissue will be obtained by fine-needle aspiration – a method used in small birds6 and successfully modified for sampling from insectivorous bats7. Total lipids will be extracted and fatty acid profiles will be determined through gas chromatography. From these data, I will be able to statistically compare individual composition of stored fatty acids as well as characterize – for the first time – mobilized energy profiles in mated vs. unmated females within, and across, a natural elevational cline in the White-Inyo Mountains. The potential interplay between reproductive constraints and environmental conditions represents a gap in our understanding of basic bat biology and the results of this work will provide data which can inform predictions surrounding the conservation, and management, of bat populations threatened by changes in climate and physiological stress during hibernation (e.g. white nose syndrome).

Visit #66684 @White Mountain Research Center

Approved

Under Project # 44050 | Research

Hibernation Energetics in Townsend's Big Eared Bats

graduate_student - University of California, Berkeley

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Mattina Alonge Feb 6 - 11, 2020 (6 days)

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Owens Valley Station, Room & Board 0 Feb 6 - 11, 2020
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