A new study finds that one of the first bats ever listed as endangered lost 10 percent of its population every year between 2006 and 2009 to white-nose syndrome, the bat disease that has already wiped out nearly seven million bats in North America. The Indiana bat had made modest population gains in recent years prior to the onset of the disease, but a report recently released by the U.S. Geological Survey says white-nose syndrome has reversed that trend in some areas.
In recent winters, the disease spread into the core midwestern range of the species, which could result in even more dramatic declines.
“Indiana bats are beginning to slip away from us,” said Mollie Matteson, a bat specialist with the Center for Biological Diversity, which this spring petitioned the White House for national action on the disease outbreak. “At this point, every remaining Indiana bat is a precious survivor. We need to take every possible step to save them from threats, including white-nose syndrome.”
The disease has hit Indiana bats the hardest in the Northeast and in Appalachia. Bat scientists fear the dramatic mortality rates observed in the eastern portions of the species’ range will soon occur in Indiana bat stronghold states, such as Indiana, Kentucky and Missouri.
The Indiana bat was first listed as a federally endangered species in 1967, when people still purposefully killed entire colonies of bats “for fun” or out of a mistaken belief that they were “vermin.” Measures to protect the colonies, such as the gating of important hibernating sites, have helped to reduce those losses. But many threats remain, including logging of summer roosting trees and pesticide spraying of insects that bats depend on for food. In recent years, the boom in oil and gas fracking in the eastern states, as well as wind-energy installations that kill bats with moving turbine blades, have created new hazards for the animals.
“Indiana bats were already struggling to survive – now white-nose syndrome is pushing them headlong into extinction,” Ms. Matteson said.
Since 2006, when white-nose syndrome was first discovered in upstate New York caves, the disease has spread to 19 states and four Canadian provinces. Last winter biologists discovered white-nose syndrome in Missouri, marking the first time the disease had been confirmed west of the Mississippi River.
Indiana bats have suffered mortality rates of more than 90 percent in some affected hibernation sites in the Northeast, where the disease has been present longest. The Geological Survey study notes that, so far, subpopulations of the Indiana bat are on variable trajectories, with midwestern Indiana bats holding steady in recent years or even slightly increasing. But the report’s authors say that overall, the fungal bat disease is “stalling and in some cases reversing population gains made in recent years.”
In response to the growing impact of white-nose syndrome, one of the nation’s leading scientific organizations, the American Institute of Biological Sciences, recently called for cave closures to prevent people from spreading the disease.
In the eastern United States, caves on most federal lands, many state lands and some private lands have been closed to nonessential human access the past several years to protect bats. Bat caves in the West, however, remain largely unprotected, including thousands of caves on Bureau of Land Management and U.S. Forest Service lands. To date, caves have been closed in only the Rocky Mountain Region of the Forest Service, which includes Colorado and Wyoming, and on federal land in New Mexico, where only about two dozen caves have been closed.
The Center has been a leader in the effort to enact stronger protective measures for bats, calling for cave closures on public lands and petitioning the White House Council on Environmental Quality earlier this year to direct those closures.
“The Indiana bat’s situation is about to get even more urgent,” Ms. Matteson said. “When we lose bats, we lose irreplaceable parts of our ecosystems, including the services these animals provide by eating thousands of tons of crop pests every year. And that’s a problem for all of us.”