Seasonal coat-colour moulting phenology of snowshoe hares in a Yukon boreal forest undergoing climate change.

Climate change is slowly influencing boreal forest ecosystems, with rising temperatures and altered snow conditions driving phenological shifts in many plant and animal species. Using 7 years (2016-2022) of camera trap data from the Kluane Lake region, Yukon, we quantified seasonal moulting phenology and coat-colour mismatch in snowshoe hares. Autumn moult started between 28 September and 3 October and completed between 5 and 11 November, with the mean moult duration ranging from 36 to 43 days. Spring moult initiated between 12 April and 27 April and completed between 16 May and 27 May, with moult duration ranging from 24 to 38 days. Contrary to our expectations, there was no evidence of delayed or advanced moulting phenology over this 7-year period. The mismatch between snowshoe hare coat colour and background showed an increasing trend and average whiteness of the snowshoe hare coat in autumn declined. Temperature and snow variables influenced various aspects of seasonal moulting phenology, in some cases in the opposite direction. Long-term studies utilizing intrinsic and high-resolution microclimatic data and behavioural observations are needed to understand how moulting phenology and mismatch affect predator-prey dynamics and snowshoe hare demography and population dynamics as climate change continues.