White-nose syndrome has killed over 90% of some North American bat species; the welfare of affected individuals and the ecological impact are both catastrophic.
Bats affected by white-nose syndrome experience repeated arousal from hibernation in cold conditions where no food is available. Each arousal consumes substantial energy reserves; animals die from starvation while still in their hibernacula. Dying bats may be seen flying erratically in winter — a visible sign of the disease's welfare impact. Individual suffering occurs at enormous scale given the mortality rates involved. Conservation interventions under study include probiotic treatments applied to cave environments, UV light therapy, and development of vaccines. The welfare and ecological implications of losing insectivorous bats — which consume billions of pest insects — are profound.