White-nose syndrome (WNS) is a fungal disease that has killed more than 90% of some North American bat populations since its emergence in 2006, causing individual suffering on an unprecedented scale among wild mammals.
WNS causes significant individual suffering. Affected bats arouse from hibernation during cold winter months when insects are unavailable, burning through fat reserves they need to survive until spring. They fly from caves in winter, sometimes visible in daylight — an abnormal behaviour indicating desperate energy depletion. Wing membrane damage from fungal growth impairs flight and water regulation. The final stages involve weakness, inability to fly, exposure to cold, and death from starvation, dehydration, or hypothermia. The scale of suffering is staggering: millions of individual bats experiencing this slow, distressing death annually for nearly two decades. The ecological consequences — reduced insect control affecting agriculture and ecosystems — compound the direct welfare tragedy.