Roost use and thermoregulation by female Australian long-eared bats (Nyctophilus geoffroyi and N. gouldi) during pregnancy and lactation1
Christopher Turbill
A B C , Gerhard Körtner A and Fritz Geiser A
+ Author Affiliations
- Author Affiliations
A Centre for Behavioural and Physiological Ecology, Zoology CO2, University of New England, Armidale, NSW 2351, Australia.
B Hawkesbury Institute for the Environment and School of Science, Western Sydney University, Richmond, NSW 2753, Australia.
C Corresponding author. Email: c.turbill@westernsydney.edu.au
Australian Journal of Zoology 67(6) 339-345 https://doi.org/10.1071/ZO20036
Submitted: 25 May 2020 Accepted: 14 September 2020 Published: 23 October 2020
Abstract
Small insectivorous bats commonly use torpor while day-roosting, even in summer. However, reproductive female bats are believed to benefit from avoiding torpor because a constant, elevated body temperature maximises the rate of offspring growth, which could increase offspring survival. We used temperature-sensitive radio-transmitters to locate roosts and document the thermal biology of pregnant and lactating females of Nyctophilus geoffroyi (9 g) and N. gouldi (11 g) at a woodland in a cool temperate climate. Unlike males, reproductive female Nyctophilus spp. roosted as small groups (<25) within insulated tree cavities. Roost switching occurred every 3.7 ± 1.5 (N. geoffroyi) or 1.7 ± 0.8 days (N. gouldi), and radio-tagged individuals roosted together and apart on different days. Skin temperature during roosting was most often between 32 and 36°C, and torpor was used infrequently. Male Nyctophilus have been shown in previous studies to use torpor daily during summer. These contrasting torpor patterns likely reflect the warmed cavities occupied by maternity colonies and the thermally unstable shallow crevices occupied by individual males. Our results support the hypothesis that availability of thermally suitable roosts will influence thermoregulatory patterns of reproductive females and hence the growth rates and survival of their offspring. Thus, it is important to conserve woodland habitat with trees in a range of decay stages to provide opportunities for selection and movement among roost trees by reproductive female bats.
Keywords: bats, body temperature, roost, thermoregulation, torpor, tree-roosting.
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