Coat colour mismatch improves survival: energetic advantages exceed lost
camouflage
Abstract
Climate warming is causing asynchronies between animal phenology and
environments. Mismatched traits, like coat colour change mismatched with
snow, typically decrease survival. However, coat change does not serve a
singular adaptive benefit of camouflage, and alternate coat change
functions may confer advantages that supersede mismatch costs. We found
that mismatch reduced autumn mortality risk of snowshoe hares in the
Yukon by 86.5 %. We suggest that the increased coat insulation and
lower metabolic rates of winter acclimatized hares confer energetic
advantages to white mismatched hares that reduce their risk of dying. We
found that white mismatched hares forage 17-77 minutes less per day than
matched brown hares between 0 and -10 ºC, thus lowering their predation
risk and increasing survival. We found no effect of mismatch on spring
mortality risk, where mismatch occurred at warmer temperatures,
suggesting a potential temperature limit where the costs of
conspicuousness outweigh energetic benefits.