White-nose syndrome, caused by the fungus Pseudogymnoascus destructans, has killed over 7 million North American bats since 2006, causing mass mortality that involves individual suffering on an enormous scale.
Individual bats dying from white-nose syndrome experience a prolonged process of fat depletion, disrupted hibernation, and eventual starvation or freezing. The welfare cost multiplied across millions of individuals represents one of the largest disease-caused wildlife welfare events in recent North American history. Emerging treatments offer hope, but the scale of ongoing mortality means active welfare interventions are needed now alongside longer-term prevention research.