White-nose syndrome, caused by the fungus Pseudogymnoascus destructans, has killed millions of bats across North America and poses a growing global threat.
White-nose syndrome causes bats to wake frequently from hibernation, depleting fat reserves and causing starvation before spring insects emerge. Affected bats display abnormal daytime activity in winter, flying in cold temperatures and congregating outside cave entrances in distress. Death from starvation and exposure follows. The scale of mortality represents enormous welfare harm across millions of individual animals. Species like the northern long-eared bat and little brown bat have experienced population crashes threatening local extinction.