Chenery Melissa, Geiser Fritz, Stawski Clare
Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia.
Department of Biology, Norwegian University of Science and Technology, Trondheim 7491, Norway.
J Mammal. 2022 Apr 14;103(4):826-834. doi: 10.1093/jmammal/gyac022. eCollection 2022 Aug.
Insectivorous bats are particularly susceptible to heat loss due to their relatively large surface area to volume ratio. Therefore, to maintain a high normothermic body temperature, bats require large amounts of energy for thermoregulation. This can be energetically challenging for small bats during cold periods as heat loss is augmented and insect prey is reduced. To conserve energy many bats enter a state of torpor characterized by a controlled reduction of metabolism and body temperature in combination with selecting roosts based upon thermal properties. Our study aimed to quantify torpor patterns and roost preferences of free-ranging little forest bats () during winter to identify physiological and behavioral mechanisms used by this species for survival of the cold season. All bats captured were male (body mass 4.9 ± 0.7 g, = 6) and used torpor on every day monitored, with bouts lasting up to 187.58 h (mean = 35.5 ± 36.7 h, = 6, total number of samples [] = 61). Torpor bout duration was significantly correlated with daily minimum and maximum ambient temperature, mean skin temperature, insect mass, and body mass of individuals and the multiday torpor bouts recorded in the cold qualify as hibernation. The lowest skin temperature recorded was 5.2°C, which corresponded to the lowest ambient temperature measurement of -5.8°C. Most bats chose tall, large, live trees for roosting and to leave their roost for foraging on warmer days. Many individuals often switched roosts (every 3-5 days) and movements increased as spring approached (every 1-2 days). Our data suggest that are capable of using the environmental temperature to gauge potential foraging opportunities and as a cue to reenter torpor when conditions are unsuitable. Importantly, frequent use of torpor and appropriate roost selection form key roles in the winter survival of these tiny bats.
食虫蝙蝠因其相对较大的表面积与体积比，特别容易散热。因此，为了维持较高的正常体温，蝙蝠需要大量能量用于体温调节。在寒冷时期，这对小型蝙蝠来说在能量方面具有挑战性，因为热量散失增加而昆虫猎物减少。为了节省能量，许多蝙蝠进入一种蛰伏状态，其特征是新陈代谢和体温受到控制地降低，同时根据热特性选择栖息地。我们的研究旨在量化冬季自由放养的小林蝠（）的蛰伏模式和栖息地偏好，以确定该物种在寒冷季节生存所使用的生理和行为机制。所有捕获的蝙蝠均为雄性（体重4.9±0.7克，=6），在监测的每一天都使用蛰伏，蛰伏期长达187.58小时（平均=35.5±36.7小时，=6，样本总数[]=61）。蛰伏期持续时间与每日最低和最高环境温度、平均皮肤温度、昆虫质量以及个体体重显著相关，在寒冷天气记录的多日蛰伏期可视为冬眠。记录到的最低皮肤温度为5.2°C，这与最低环境温度测量值-5.8°C相对应。大多数蝙蝠选择高大、大型的活树作为栖息地，并在较温暖的日子离开栖息地觅食。许多个体经常更换栖息地（每3-5天一次），随着春天临近（每1-2天一次）活动增加。我们的数据表明，能够利用环境温度来评估潜在的觅食机会，并在条件不适宜时作为重新进入蛰伏的线索。重要的是，频繁使用蛰伏和适当选择栖息地在这些小蝙蝠的冬季生存中起着关键作用。
