Little brown bats facing regional extinction from White-nose fungus
It could be even worse than we thought. Since it was first discovered in 2006, a fungus that grows on bats has killed up to 99% of the individuals in some colonies in eastern North America, and could drive one species to regional extinction. The grim news, reported in the current issue of Science, highlights the need for better monitoring of wildlife diseases, researchers say.
Since scientists first documented a powdery, white fungus growing on bats in Howe Cave near Albany, New York in February 2006, White-nose syndrome (WNS) has spread to bat colonies across the eastern United States and Canada. The disease has now struck at least 115 colonies, reports a team led by Winifred F. Frick of the University of California, Santa Cruz. Population losses have ranged from 33% to 99%, with the average colony losing nearly three-quarters of its bats. Such sharp declines “raise serious concerns about the impact of WNS on the population viability of affected bat species,” the authors write.
One common species – the little brown bat (Myotis lucifugus) – appears to be especially vulnerable. Tapping bat population data collected in the 30 years before the arrival of WNS, the team used computer models to forecast how populations might change in the post White-nose era. The simulations suggest a 99% probability that the little brown bat will become extinct in the Northeastern United States within 16 years if WNS mortality continues at high rates. Even a more optimistic scenario suggests the regional population could plummet from 6.5 million to just 65,000 bats in just 20 years.
If there is any good news in the study, it is that researchers are getting faster at identifying serious emerging wildlife diseases, writes Peter Daszak of New York City-based EcoHealth Alliance in accompanying essay. It took two decades, he notes, for scientists and conservationists to agree that the fungal disease chytridiomycosis posed a serious threat to amphibians around the world. This time, it took just a few years. Still, he says “we need a new international body focused on global wildlife disease, perhaps under the auspices of the International Union for the Conservation of Nature.” Besides addressing emerging threats to wildlife, Daszak says the group might help prevent the next SARS or avian flu pandemics by identifying wildlife diseases might eventually jump to people. – David Malakoff
Source: Frick, WF. “An Emerging Disease Causes Regional Population Collapse of a Common North American Bat Species.” Science, p. 679, Vol 329, 6 August 2010.
Image Alan Hicks|courtesy Science