School of Natural Sciences and ARC Centre of Excellence for Australian Biodiversity and Heritage, University of Tasmania, Hobart, Tasmania, 7001, Australia; School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia.
School of Natural Sciences and ARC Centre of Excellence for Australian Biodiversity and Heritage, University of Tasmania, Hobart, Tasmania, 7001, Australia.
J Therm Biol. 2024 Oct;125:103961. doi: 10.1016/j.jtherbio.2024.103961. Epub 2024 Oct 9.
Mammals use burrows to behaviourally thermoregulate, save water, and avoid predation. The advantages of burrows vary not only seasonally but also with burrow depth. To quantify these effects, we used biophysical ecological models, which predict an animal's energetic and hydric costs within a characterised microclimate. For Australia's three extant wombat species, we quantified variation in the energetic advantage of burrows spatially, temporally, and with burrow depth. We simulated resting wombats with different traits (e.g., body size, fur) in different microclimates (above ground and burrows of varying depth) at six sites across Australia, two for each wombat species, over five years (1980, 1990, 2000, 2010, 2020). We assessed time spent within their thermoneutral zone-heat production equals heat loss thus minimising energy and water expenditure -and frequency of extreme heat stress (i.e., no viable hydric solution for the conditions stipulated). Our findings show that burrows are essential for reducing energetic and hydric costs and for survival during the hottest season in areas with no shade, e.g., the semi-arid zone. We found no evidence that extreme heat stress has increased temporally i.e., due to climate change, but it was frequently predicted in shallow burrows in 2020, having rarely been previously forecast. For energy requirements, we found lower thermoregulatory costs for deeper burrows in the cold season and for shallow burrows in the hot season. This work underscores the critical balance between wombat survival, burrow utility, and environmental dynamics, offering new insights into mechanisms that dictate mammal behaviour from a thermoregulatory perspective.
哺乳动物利用洞穴来行为调节体温、节约水分和避免被捕食。洞穴的优势不仅因季节而异，还因洞穴深度而异。为了量化这些影响，我们使用了生物物理生态模型，这些模型预测了动物在特定微气候条件下的能量和水分成本。对于澳大利亚现存的三种袋熊物种，我们从空间、时间和洞穴深度上量化了洞穴对其能量优势的影响。我们在澳大利亚六个地点（每个物种两个地点）模拟了具有不同特征（如体型、皮毛）的休息袋熊，在不同的微气候条件下（地面和不同深度的洞穴），模拟时间为五年（1980 年、1990 年、2000 年、2010 年、2020 年）。我们评估了它们在热中性区（产热等于散热，从而最小化能量和水分消耗）内的时间和极端热应激的频率（即在规定条件下没有可行的水分解决方案）。我们的研究结果表明，在没有遮荫的地区（如半干旱地区），洞穴对于降低能量和水分成本以及在最热季节的生存至关重要。我们没有发现极端热应激随时间增加的证据，即由于气候变化，但在 2020 年的浅层洞穴中经常预测到这种情况，而以前很少预测到。对于能量需求，我们发现深洞穴在寒冷季节和浅洞穴在炎热季节的体温调节成本较低。这项工作强调了袋熊生存、洞穴利用和环境动态之间的关键平衡，为从体温调节角度解释哺乳动物行为的机制提供了新的见解。
