Some people consider them to be rats with wings, others think about vampire legends. However, bats are an important part of most terrestrial ecosystems. In New York and neighbouring states, thousands of bats have succumbed to a fungal disease.

Researchers have coined the name “white-nose syndrome” from the tufty fungal growths appearing on some bats’ noses. In early 2007, bat mortality continued until the spring dispersal from caves. However, in the past few months of this winter, bats are again dying. A minimum of 14 caves are infected, located in New York, Vermont, and Massachusetts. As many as half a million bats may be affected, including little brown bats, eastern pipistrelles, northern long-eared bats, and the endangered Indiana bat.

Bats are voracious insect predators, consuming thousands of prey in a single night. Without bats, insect populations explode, potentially affecting agricultural crops. Additionally, bats are effective at keeping down mosquito numbers - one bat can eat up to 1000 mosquitoes in an hour.

Several graduate students from Indiana State University have been investigating possible causes of the die-off. Bats were less responsive to intruders in the caves; instead of wakening and taking flight, many bats never roused when caves were entered by researchers. Another observation was bats attempting to hunt for food in February, when prey are scarce. In general, the bats are underweight and have depleted fat reserves, forcing them to take wing when hibernation should be continuing.

It is unclear whether the fungus is responsible for all the bat deaths.The fungus may grow opportunistically on bats already weakened by another unknown factor. Bat populations already suffer from various human impacts, including habitat destruction, disturbances, pesticide use, and other contaminants.

One concern is that spelunkers and other cave visitors may inadvertently track fungal spores into new areas. The US Fish and Wildlife Service has set out some guidelines to minimize contamination:
• Avoid touching any bats, either dead or alive.
• Take photographs of bats with white patches or other unusual appearance.
• Decontaminate clothing and gear before entering other caves.
• Report potentially affected bats, dead bats outside caves, and numerous bats seen outside.