Researchers have found a clue in the mysterious die-off of bats that has struck the Northeast -- a new fungus that so far seems to be present only in bats and in caves where the die-off has occurred.
"The fungus is in some way involved in causing the bats to starve to death," said biologist Thomas Tomasi of Missouri State University in Springfield. "They are burning up too many calories, at a rate faster than they can sustain."
Bat experts are not yet sure, however, whether the fungus is the cause of the widespread deaths or is simply an opportunistic microorganism infecting animals that have already been weakened by some unknown threat.
"Whether it is the primary cause or not, we still have to find out whether it is newly introduced or if there are other factors that need to be addressed," said biologist Merlin Tuttle, founder and president of Bat Conservation International.
The disease, which bears many similarities to the colony collapse disorder that has decimated honeybee colonies across the country, first appeared in a cave near Albany, N.Y., in the winter of 2006. It has since spread to at least three other states in the region.
The most obvious symptom is the presence of a visible halo of white fungus around the faces of afflicted animals -- hence the common name, white-nose syndrome. The affected animals become severely emaciated, often emerging from their hibernation caves in the dead of winter in a futile search for food.
In some bat caves, more than 90% of the inhabitants died last winter. Overall populations have declined about 75% in the affected areas.
"I have been studying bats for 40-plus years, and this is unparalleled in the history of what I know about bats," said biologist Thomas H. Kunz, director of the Center for Ecology and Conservation Biology at Boston University.
Although bats can seem scary, a significant die-off could have severe economic and health consequences.
Bats represent about a quarter of all mammalian species and are voracious eaters of insects that attack crops and carry diseases. A single bat can eat more than 100% of its body weight in bugs each night.
In Texas, Tuttle said, free-tailed bats eat 200 tons of insects a night. Studies have shown that bats in the state consume large quantities of corn ear and armyworm moths that migrate from the south each spring.
The new study, reported Thursday in the online version of the journal Science, at least identifies what is producing the white nose.
