Thermal Physiology of Endothermic Animals

The thermal physiology of endothermic animals centres on the capacity to generate and regulate internal heat independently of ambient conditions, thereby maintaining a narrow range of body temperatures essential for enzyme function and cellular processes. Within a species-specific thermal neutral zone, basal metabolic rate suffices for heat balance, but deviations trigger active thermoregulatory mechanisms such as shivering and non-shivering thermogenesis, peripheral vasoconstriction or dilation, and changes in posture or microhabitat selection. When external temperatures exceed critical thresholds, endotherms rely on evaporative cooling, heterothermy or torpor to dissipate excess heat or conserve energy, whereas exposure to cold elicits increased metabolic heat production and insulative adjustments in fur or plumage. These physiological responses are intimately linked to ecological strategies, influencing habitat use, reproductive success and biogeographical distributions. In the context of rapid climate change, understanding the interplay between metabolic demands, water balance and behavioural thermoregulation has never been more urgent, as rising mean temperatures and more frequent extremes threaten species’ persistence and ecosystem functioning. Advances in biophysical modelling, remote thermal imaging and field experiments are now elucidating species-specific vulnerabilities and potential conservation interventions, from identifying thermal refugia to optimising habitat management under future climate scenarios.

Research from Nature Portfolio

Recent studies have combined large-scale climate projections with mechanistic biophysical models to predict the physiological impacts of warming on warm-adapted bird communities. These analyses reveal that temperature increases do not translate uniformly into physiological stress, with spatially heterogeneous patterns of vulnerability among desert species and the persistence of low-impact refugial areas often lying outside existing protected networks. Elsewhere, continent-wide phylogenetic surveys have demonstrated that near-infrared reflectivity of integumentary structures confers significant thermal protection, particularly in smaller avian species, by reducing solar heat gain and associated water loss. Further work employing high-resolution thermal imaging has shown that surface temperature variations around the eye region can non-invasively indicate both energy reserves and stress hormone levels in free-living birds, offering a novel tool for assessing physiological state across life stages.

Thermal Physiology of Endothermic Animals publication trend

The graph below shows the total number of articles in thermal physiology of endothermic animals across all publications each year (not limited to Nature Index journals).

Technical terms

Endothermy: The physiological capability to maintain a stable internal body temperature through metabolic heat production regardless of ambient temperature.

Thermoregulation: The suite of behavioural and physiological processes that balance heat production and heat loss to maintain homeostasis.

Basal metabolic rate: The minimal rate of energy expenditure required for maintenance of essential physiological functions at rest within the thermal neutral zone.

Evaporative cooling: A heat dissipation mechanism in which water is evaporated from body surfaces or respiratory passages to remove excess heat.

Thermal neutral zone: The range of ambient temperatures over which endotherms can maintain body temperature without elevating metabolic heat production or activating energy-intensive cooling mechanisms.

References

1. Global patterns of climate change impacts on desert bird communities. Nature Communications (2023).
2. Reflection of near-infrared light confers thermal protection in birds. Nature Communications (2018).
3. Eye region surface temperature reflects both energy reserves and circulating glucocorticoids in a wild bird. Scientific Reports (2018).
4. Adaptation to fluctuating temperatures across life stages in endotherms. Trends in Ecology & Evolution (2024).
5. Experimental nest cooling reveals dramatic effects of heatwaves on reproduction in a Mediterranean bird of prey. Global Change Biology (2023).
6. A trait-based assessment of southern African arid-zone birds' vulnerability to climate change. Biological Conservation (2023).