White-nose syndrome, caused by a devastating fungal pathogen, has killed millions of North American bats, and its detection in Europe raises urgent welfare and conservation concerns.
White-nose syndrome causes a particularly welfare-relevant pattern of suffering in affected bats. During winter hibernation, when bats are minimising energy expenditure, the fungus irritates the skin and disrupts physiological regulation, causing bats to arouse more frequently than normal. These extra arousal events are metabolically costly: each unnecessary awakening burns fat reserves equivalent to days of hibernation. By late winter, affected bats have exhausted their fat stores and begin to die of starvation while hibernating, or emerge prematurely and starve in the absence of insect prey. The suffering extends from individual physiology to colony-level collapse: some colonies have lost 99% of members within a few seasons. The apparent immunity of European bats offers hope that North American populations may eventually develop partial resistance through selective pressure, but the conservation and welfare losses in the interim are enormous. UK bat monitoring provides early warning if more virulent strains or bat species with lower immunity are affected.