Goldingay Ross L, Thomas Karen J
School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, New South Wales, 2480, Australia.
Bendigo Field Naturalists Club, Spring Gully PO, Bendigo, Victoria, 3550, Australia.
J Therm Biol. 2021 May;98:102899. doi: 10.1016/j.jtherbio.2021.102899. Epub 2021 Mar 29.
Nest boxes are used to manage populations of tree-cavity dependent birds and mammals. Concerns have been raised that due to their poor insulative properties nest boxes may cause heat stress and occasionally death during summers of extreme maximum temperatures. Our study investigated whether this nest box heat stress hypothesis applies to two small cavity-dependent mammals (brush-tailed phascogales and sugar gliders). Focusing on days when ambient temperature reached ≥40 °C, we recorded: i) temperatures within occupied nest boxes, ii) temperatures within nearby unoccupied tree cavities, iii) the duration of temperatures of ≥40 °C within nest boxes, iv) whether direct mortality was observed, and v) the relative abundance of these species in nest boxes before and after a very hot summer. When ambient temperature reached ≥40 °C, nest boxes were equivalent to ambient or 1-2 °C cooler, whereas tree cavities were 3-7 °C cooler than ambient. Exposure in nest boxes to temperatures of ≥40 °C lasted an average of 2-8 h. We observed no mortality over 65 records of phascogales and 31 records of gliders in nest boxes on days when ambient reached ≥40 °C. No decline in abundance was recorded after a summer with 11 days of temperatures ≥40 °C, with each species subsequently occupying >40 nest boxes. Our observations suggest these species are tolerant of the high temperatures that occurred. Nonetheless, provision of nest boxes designed to minimise summer heating is recommended.
巢箱被用于管理依赖树洞的鸟类和哺乳动物种群。有人担心，由于巢箱的隔热性能较差，在极端最高气温的夏季，巢箱可能会导致热应激，偶尔还会造成死亡。我们的研究调查了这种巢箱热应激假说是否适用于两种依赖小洞穴的小型哺乳动物（帚尾袋鼬和蜜袋鼯）。我们聚焦于环境温度达到≥40°C的日子，记录了以下内容：i）被占用巢箱内的温度，ii）附近未被占用树洞的温度，iii）巢箱内温度≥40°C的持续时间，iv）是否观察到直接死亡情况，以及v）在一个非常炎热的夏季前后，这些物种在巢箱中的相对丰度。当环境温度达到≥40°C时，巢箱内的温度与环境温度相当或比环境温度低1 - 2°C，而树洞的温度比环境温度低3 - 7°C。巢箱内暴露于≥40°C温度下的时间平均持续2 - 8小时。在环境温度达到≥40°C的日子里，我们在65次帚尾袋鼬记录和31次蜜袋鼯记录中均未观察到死亡情况。在经历了11天温度≥40°C的夏季后，没有记录到物种丰度的下降，随后每个物种都占据了超过40个巢箱。我们的观察结果表明，这些物种能够耐受所出现的高温。尽管如此，建议提供旨在尽量减少夏季热量的巢箱。
