What is the biggest killer of bats?

The biggest killer of bats depends on whether you are talking about natural predators or overall causes of bat mortality, but today the biggest killer of bats overall is white-nose syndrome and human-related threats rather than natural predators. White-nose syndrome is a fungal disease caused by Pseudogymnoascus destructans that thrives in cold, damp caves where bats hibernate, and since it was discovered in North America in 2006 it has killed millions of hibernating bats, causing declines of over 90 percent in some species like little brown bats, and is considered the most devastating threat to bat populations. Other major killers include habitat loss from deforestation and cave disturbance, wind turbines that kill bats during migration, especially migratory tree bats like hoary bats, vehicle collisions, and intentional killing by humans who misunderstand bats. Natural predators like owls, hawks, snakes, raccoons, and cats do kill bats but account for far fewer deaths than disease and human threats. Pesticides that reduce insect food and poison bats also contribute. In the past, natural predators were significant, but today white-nose syndrome is the single biggest killer of hibernating bats in North America, while wind turbines are a leading killer of migratory bats. Conservation efforts focus on protecting caves, installing bat houses, and developing treatments for white-nose syndrome.