Federal biologists announced today that up to 6.7 million bats in 16 states and four Canadian provinces may have died from the white-nose fungus since it was detected six years ago, a die-off that a conservationist today called "a potential extinction event,"

The U.S. Fish and Wildlife Service said that at least 5.5 million bats are estimated to have died from so-called white-nose syndrome, a disease first documented on bats hibernating in cave near Albany in February 2006. Biologists report mortality rates of 90% to 100% at some sites and expect the disease to keep spreading through several species, including some that are endangered.

"This startling new information illustrates the severity of the threat that white-nose syndrome poses for bats, as well as the scope of the problem facing our nation. Bats provide tremendous value to the U.S. economy as natural pest control for American farms and forests every year, while playing an essential role in helping to control insects that can spread disease to people,"
The cause is a mystery.