Unusually warm winters are disrupting hedgehog hibernation patterns, with climate change causing both premature arousal and inadequate hibernation that threatens individual survival.
Hedgehog hibernation welfare in a warming climate illustrates how climate change creates welfare harm through the disruption of evolved physiological adaptations. Hibernation in hedgehogs is not simply sleep but a profound metabolic depression requiring specific environmental triggers - falling temperatures and reducing day length - to initiate and maintain. When autumn temperatures remain warm into November and December, hedgehogs continue being active when they should be accumulating torpor, reducing the fat reserves available for winter survival. When warm spells interrupt mid-winter hibernation, arousal is metabolically expensive - a hedgehog that wakes on a warm January day burns fat reserves equivalent to weeks of torpor, then must re-enter hibernation in already-depleted condition. Young hedgehogs born in late summer litters face the greatest risk: insufficient time between birth and winter onset means they cannot accumulate the body weight (600g minimum) needed to survive hibernation. Some wildlife rehabilitators now overwinter late-season juvenile hedgehogs in controlled conditions to prevent starvation, providing direct welfare intervention for climate-impacted animals.