Function and underlying mechanisms of seasonal colour moulting in mammals and birds: what keeps them changing in a warming world?

Summary

This comprehensive systematic review synthesises the adaptive functions and mechanistic basis of seasonal coat colour moulting across birds and mammals distributed in the northern hemisphere. The authors establish seasonal camouflage against snow as the primary selective driver and photoperiod as the predominant phenological cue, whilst identifying critical knowledge gaps particularly regarding avian species. The review concludes that limited phenological plasticity in moulting timing may constrain populations' ability to track rapidly changing snow cover under climate change, necessitating both evolutionary adaptation and enhanced management strategies.

UK applicability

Whilst the UK has limited populations of seasonally white species (mountain hare in Scotland), the mechanistic findings and climate adaptation framework are relevant to understanding phenological mismatch in British wildlife under warming conditions. The conclusions regarding adaptive constraints and management strategies may inform UK conservation policy for at-risk subspecies and inform broader understanding of climate-driven phenological change.

Key measures

Adaptive functions of coat colour change; phenological drivers (photoperiod); neuroendocrine mechanisms; species-specific moult plasticity; camouflage mismatch risk under climate change

Outcomes reported

The study synthesised adaptive functions and mechanistic bases of seasonal coat colour moulting across over 20 bird and mammal species in temperate and polar regions. It identified photoperiod as the primary phenological cue and seasonal camouflage against snow as the main selective driver, whilst highlighting conservation risks from camouflage mismatch as snow cover duration decreases.

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