White-nose Syndrome is on the move again – as it has been for each of the past four winters. Early reports from surveys of bat-hibernation sites confirm this devastating wildlife disease has reached North Carolina and Indiana. That brings to 14 the number of U.S. states, plus two Canadian provinces, whose bat populations are being ravaged by WNS. The WNS-associated fungus, although not the disease itself, was reported last year in two other states, Missouri and Oklahoma.
WNS was confirmed in two little brown myotis (Myotis lucifugus) in an Indiana cave in late January. In North Carolina, tests confirmed the disease in six bats – little browns, northern myotis (M. septentrionalis) and tri-colored bats (Perimyotis subflavus) – from one cave and one mine in the western part of the state.
"Indiana and North Carolina are only the beginning," worries Nina Fascione, Bat Conservation International's Executive Director. "Since its discovery in New York five years ago, the fungus has traveled more than halfway across the United States, and biologists worry it will reach even farther westward as the winter progresses. The results of this winter will shed light on many questions surrounding this lethal disease."
Cave and mine surveys are being undertaken, or will be in the next few weeks, across much of the country, so more grim reports of WNS and the associated fungus are likely. The disease already has killed well over a million bats, with mortality rates approaching 100 percent at some sites. It has, so far, attacked only hibernating bats, which include 25 of the 46 U.S. bat species.
BCI White-nose Syndrome Coordinator Mylea Bayless notes that WNS and the fungus are poised to enter areas that are so far untouched and where the landscape, climate and bat populations are somewhat different from those of the WNS-battered northeast. It is far from clear how White-nose Syndrome will behave in those areas.
With the fungus found last winter on asymptomatic bats in Oklahoma and Missouri, Bayless said, scientists may learn new information about the incubation period of the Geomyces destructans fungus. Surveys of those sites will likely reveal "whether bat populations can harbor the fungus for at least two years without developing the disease."
The two states also put the WNS fungus on the edge of the American West, with distinct geology, a generally drier climate and a whole new community of bats that mostly form smaller colonies than those of eastern states.
And if White-nose Syndrome spreads farther south along the Eastern Seaboard, she said, it will reach warmer areas where many bats spend the winter in cisterns, hollow trees and beneath loose tree bark, rather than in caves and mines. "These bats seem naturally to arouse more often during winter. Maybe the disease won't be as devastating to bats in southern populations. We just don't really know how White-nose Syndrome will behave in these new areas."
Whether good news or bad, bat scientists and conservationists are likely to learn quite a bit in the weeks ahead.
You can help Bat Conservation International and its partners search for solutions to White-nose Syndrome and other critical threats to bats. Please visit www.batcon.org/donate.