Why have they closed more than 200 caves across the US that provide bat habitat? The management is trying to prevent the human "boot spread" of an emerging fungal threat to the colonies known as White Nose Syndrome (WNS). Millions of bats have died and there is no scientifically accepted method to manage the problem yet. Details after the fold.
The leading bat non-profit says:
White-nose Syndrome, named for a fungus found on the faces, ears and/or wings of most infected bats, has killed more than a million hibernating bats of six species since it was first detected in a single New York cave in February 2006. Since then, it has spread rapidly across the northeastern states and beyond, reaching as far south as Virginia this past winter. WNS has killed up to 95 percent or more of bats in affected hibernation caves and mines. Whole species, including the already-endangered Indiana and gray bats, are in imminent peril. Their loss could have serious consequences for the wellbeing of North American ecosystems, agriculture and human health. These bats are prodigious predators of night-flying insects, including many damaging agricultural and forest pests. Many bats, including the WNS-battered little brown bat, eat an average of half their body weight in insects each night from mid-April to mid-October. Conservative estimates show that the million bats already lost to WNS would have eaten about 1.39 million pounds of insects each year. Without these bats, crop damage and pesticide use will almost certainly increase.
The fungus has been identified by a team led by David Blehert at the U.S. Geological Survey National Wildlife Health Center in Madison, Wis. Direct microscopy and culture analyses demonstrated that the skin of WNS-affected bats is colonized by a psychro-philic fungus that is phylogenetically related to Geomyces spp. but with a conidial morphology distinct from characterized members of this genus.
From the May 2009 Consensus Statement of the scientific panelists:
White-Nose Syndrome (WNS) is a devastating disease of hibernating bats that has caused the most precipitous decline of North American wildlife in recorded history. Since it was first discovered in 2006, WNS has infected six species of insect-eating bats in the northeastern and southern U.S., causing declines approaching 100% in some populations; estimated losses have exceeded one million bats over the past three years. If the spread of WNS is not slowed or halted, further losses could lead to the extinction of entire species and could more than quadruple those that are federally listed as endangered in the U.S. Such losses alone are expected to have unprecedented consequences on ecosystem health throughout North America, with unknown economic consequences. Most bat species in North America feed on night-flying insects, of which many are pests of forests, agriculture, and garden crops or pose risks to human health. The number of insects consumed annually by one million bats is staggering—equivalent to 694,456 tons—emphasizing the extraordinary value of these bats to the normal function of both terrestrial and aquatic ecosystems. Establishment of a national comprehensive research program is urgently needed to identify underlying mechanisms causing WNS and to develop sound management solutions.
Leading experts in the fields of bat physiology, fungal ecology, ecotoxicology, disease and environmental modeling, among others, will gather at a workshop at The National Institute for Mathematical and Biological Synthesis (NIMBioS), June 29-July 1, in Knoxville, Tenn., to explore the disease and to develop solutions to manage it. Workshop organizer Gary McCracken from the University of Tennessee, Knoxville said:
It does not kill all species. In affected species, roughly 5-10 percent survive, which is a viable survival rate. Given that there is evidence of resistance to the fungus and that it is not pathogenic to native bats in Europe, the potential exists that its spread is self-limiting.
Donations to the non-profit can be made here.