Rock ptarmigan in Scotland face mismatch between their white winter camouflage and increasingly snowless winters, making them highly vulnerable to predation.
Ptarmigan in white plumage on snow-free ground are highly visible to raptors and mammalian predators, experiencing increased predation risk and chronic predator vigilance stress. Individuals spending more time in alert posture rather than feeding face nutritional deficits during energetically demanding winter months. Climate mismatch between evolved colour morphs and environmental conditions creates ongoing welfare burden as warming accelerates. Population declines from increased predation reduce overall population fitness and genetic diversity.