Tree-hugging koalas demonstrate a novel thermoregulatory mechanism for arboreal mammals

Briscoe, Natalie J., Handasyde, Kathrine A., Griffiths, Stephen R., Porter, Warren P., Krockenberger, Andrew, and Kearney, Michael R. (2014) Tree-hugging koalas demonstrate a novel thermoregulatory mechanism for arboreal mammals. Biology Letters, 10 (6). pp. 1-5.

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Abstract

How climate impacts organisms depends not only on their physiology, but also whether they can buffer themselves against climate variability via their behaviour. One of the way species can withstand hot temperatures is by seeking out cool microclimates, but only if their habitat provides such refugia. Here, we describe a novel thermoregulatory strategy in an arboreal mammal, the koala Phascolarctos cinereus. During hot weather, koalas enhanced conductive heat loss by seeking out and resting against tree trunks that were substantially cooler than ambient air temperature. Using a biophysical model of heat exchange, we show that this behaviour greatly reduces the amount of heat that must be lost via evaporative cooling, potentially increasing koala survival during extreme heat events. While it has long been known that internal temperatures of trees differ from ambient air temperatures, the relevance of this for arboreal and semi-arboreal mammals has not previously been explored. Our results highlight the important role of tree trunks as aboveground 'heat sinks', providing cool local microenvironments not only for koalas, but also for all tree-dwelling species.

Item ID: 36181
Item Type: Article (Research - C1)
ISSN: 1744-957X
Keywords: behavioural thermoregulation, biophysical models, koala, climate change, microclimate selection
Funders: Holsworth Wildlife Endowment, Australian Research Council (ARC)
Projects and Grants: ARC Linkage grant LP0989537
Date Deposited: 12 Nov 2014 12:12
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060203 Ecological Physiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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