Behavioural plasticity in snowshoe hares reflects predator recognition but not camouflage mismatch

Shifts in predator-prey interactions in response to environmental change can affect population dynamics and community structure, but have received relatively little attention in the climate change literature. Seasonally colour-moulting species face increased predation risk when winter-white individuals experience camouflage mismatch in snowless conditions. While hares (genus Lepus) exhibit behavioural plasticity to reduce predation risk in other contexts, hares in populations of winter-white individuals have demonstrated limited capacity to adjust behaviour to mitigate mismatch or its consequences. Little is known about antipredator behaviour in polymorphic populations of sympatric polyphenic winter-white and invariant winter-brown individuals that experience contrasting camouflage mismatch across seasons. We examined escape behaviours in a polymorphic population of snowshoe hares (Lepus americanus) including both winter-white and winter-brown individuals. In field experiments, we assessed plasticity in escape behaviour in response to predator type and camouflage mismatch. Using 224 measurements of concealment and flight initiation distance in 74 wild hares, we tested whether escape behaviour varied with colour morph and camouflage mismatch. We also quantified discrete escape decisions (flight, vegetation refuge or subsurface refuge) by 29 individual hares in 52 predator escape trials to test for behavioural responses to predator type (humans, hunting dogs Canis familiaris and goshawks Astur atricapillus). Linear mixed-effects models revealed no relationship between colour morph or mismatch and either concealment or flight initiation distance, suggesting a lack of behavioural adjustment to reduce mismatch-associated predation risk in both winter-white and winter-brown hares. In contrast, hares exhibited strong behavioural plasticity in response to predator type, using subsurface refuges more often in trials with avian, but not terrestrial predators. The odds of subsurface refuge use were 14.3 times higher in trials with goshawks compared to human trials. Collectively, we find that winter-white and winter-brown snowshoe hares exhibit predator recognition and corresponding behavioural plasticity to different predator types, but not to camouflage mismatch, highlighting limits to behavioural plasticity in response to climate-driven increases in predation risk.