Thermoregulatory value of cracking‐clay soil shelters for small vertebrates during extreme desert conditions

Abstract

Deserts exhibit extreme climatic conditions. Small desert-dwelling vertebrates have physiological and behavioral adaptations to cope with these conditions, including the ability to seek shelter. We investigated the temperature (T) and relative humidity (RH) regulating properties of the soil cracks that characterize the extensive cracking-clay landscapes of arid Australia, and the extent of their use by 2 small marsupial species: fat-tailed and stripe-faced dunnarts (Sminthopsis crassicaudata and Sminthopsis macroura). We measured hourly (over 24-h periods) the T and RH of randomly-selected soil cracks compared to outside conditions, during 2 summers and 2 winters. We tracked 17 dunnarts (8 Sminthopsis crassicaudata and 9 Sminthopsis macroura) to quantify their use of cracks. Cracks consistently moderated microclimate, providing more stable conditions than available from non-crack points, which often displayed comparatively dramatic fluctuations in T and RH. Both dunnart species used crack shelters extensively. Cracks constitute important shelter for small animals during extreme conditions by providing a stable microclimate, which is typically cooler than outside conditions in summer and warmer in winter. Cracks likely play a fundamental sheltering role by sustaining the physiological needs of small mammal populations. Globally, cracking-clay areas are dominated by agricultural land uses, including livestock grazing. Management of these systems should focus not only on vegetation condition, but also on soil integrity, to maintain shelter resources for ground-dwelling fauna.

Fine‐scale environmental heterogeneity and conservation management: Beach‐cast wrack creates microhabitats for thermoregulation in shorebirds

“…In addition, our findings support that more heterogeneous environments can reduce the costs for thermoregulation in animals (Basson et al, 2017;Ryeland et al, 2021). Importantly, microtopographic features, such as boulders (Shi et al, 2014) and cracks in the soil (Waudby & Petit, 2017), have been shown to provide insulation from extreme temperatures. Therefore, future studies should investigate whether microclimates created by beach-cast wrack assist thermoregulation in shorebirds during extreme heat events, which are increasing in our study area due to climate change (Braganza et al, 2013).…”

Population dynamics of dasyurid marsupials in dryland Australia: Variation across habitat and time

“…These preferences are consistent with published information on habitat use in each species (e.g. Dickman et al ; Haythornthwaite ; van Dyck & Strahan ; Pavey et al ; Waudby & Petit ; Molyneux et al ).…”

The role of grass-tree Xanthorrhoea semiplana (Asphodelaceae) canopies in temperature regulation and waterproofing for ground-dwelling wildlife

“…However, these Scott Creek data show very small standard errors. Such small standard errors also appear in Keppel et al (2017) for grass-trees in summer and Waudby and Petit (2017) for soil cracks in summer, indicating that similar shade types are associated with similar temperatures in the same environment at the same time. We are thus confident that means are fair representations of temperatures.…”