Subtropical mouse-tailed bats use geothermally heated caves for winter hibernation.
We report that two species of mouse-tailed bats (Rhinopoma microphyllum and R. cystops) hibernate for five months during winter in geothermally heated caves with stable high temperature (20°C). While hibernating, these bats do not feed or drink, even on warm nights when other bat species are active. We used thermo-sensitive transmitters to measure the bats' skin temperature in the natural hibernacula and open flow respirometry to measure torpid metabolic rate at different ambient temperatures (Ta, 16-35°C) and evaporative water loss (EWL) in the laboratory. Bats average skin temperature at the natural hibernacula was 21.7 ± 0.8°C, and no arousals were recorded. Both species reached the lowest metabolic rates around natural hibernacula temperatures (20°C, average of 0.14 ± 0.01 and 0.16 ± 0.04 ml O2 g(-1) h(-1) for R. microphyllum and R. cystops, respectively) and aroused from torpor when Ta fell below 16°C. During torpor the bats performed long apnoeas (14 ± 1.6 and 16 ± 1.5 min, respectively) and had a very low EWL. We hypothesize that the particular diet of these bats is an adaptation to hibernation at high temperatures and that caves featuring high temperature and humidity during winter enable these species to survive this season on the northern edge of their world distribution.
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel levineran1@gmail.com.
Eran
E
Levin
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Brit
B
Plotnik
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Eran
E
Amichai
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Luzie J
LJ
Braulke
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Shmulik
S
Landau
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Yoram
Y
Yom-Tov
Department of Zoology, Tel-Aviv University, Tel-Aviv, Israel.
Noga
N
Kronfeld-Schor
D000818:Animals; D059552:Caves; D002685:Chiroptera / Q000502:physiology*; D004734:Energy Metabolism; D006605:Hibernation; D006358:Hot Temperature; D014870:Water Loss, Insensible
Rhinopoma; arousals; evaporative water loss; geothermal heat; hibernation; torpor