A close-up of a bat shows the white coating of fungus on its muzzle indicative of white-nose syndrome, the disease that is decimating North America’s bat populations. How climate change will affect the virus — and the bats — is unknown. Photo: Courtesy of Ryan von Linden/New York Department of Environmental Conservation.
Much as water gouges Kentucky’s limestone caverns, white-nose syndrome is cutting through North America’s bat populations. The disease, associated with a fungus (Geomyces destructans) that is new to science, is decimating these nighttime insect eaters and alarming biologists.
How climate change will impact the fungus — and the bats — is unknown. A concern is that, like other conservation challenges such as the spread of invasive and exotic species, climate change could compound the pressures on already stressed species.
First detected in New York in February 2006, white-nose syndrome has spread rapidly through the Northeast and beyond. This spring Kentucky became the 18th state to confirm the presence of the disease or the fungus. Four Canadian provinces are also affected. So far, the disease has killed more than one million bats. U.S. Fish and Wildlife biologists fear some bat species may be wiped out completely.
Among other concerned observers: farmers. The agriculture industry counts on bats to eat an estimated $3.7 billion worth of crop pests.
Scientists are unsure how warmer average temperatures will affect the disease pattern. A century-long warming trend has accelerated over the last three decades.
A map shows the spread of white-nose syndrome through eastern North America. Eighteen states and four Canadian provinces have now confirmed the presence of the bat disease or the fungus that causes it. Map: U.S. Fish and Wildlife Service. See full size.
Bats typically have specific roost requirements, especially during winter hibernation. For certain species that hibernate in Kentucky — such as the federally endangered Indiana bat (Myotis sodalis), gray bat (Myotis grisescens), and Virginia big-eared bat (Corynorhinus townsendii virginianus) — only a small number of caves within each species’ geographic range meet these requirements.
Scientists worry that longer or hotter summers may warm cave interiors so that they no longer meet some bats’ hibernation needs. Alternatively, warming might improve the picture by shortening the duration of bat hibernation or triggering the mid-winter emergence of insects for bats to feed on, scientists speculate.
Research shows that bats affected by white-nose syndrome arouse more frequently from hibernation than healthy bats, expending energy and using up fat reserves.
To ease stress on bats and reduce the risk that humans may transmit the fungus to bats, the U.S. Fish and Wildlife Service has closed caves and mines to the public on all national wildlife refuge lands. In March 2009 the Service issued an advisory to state and federal land agencies and private landowners, recommending they follow suit. The Service reviews the advisory quarterly in consideration of the best available science. No current evidence exists that white-nose syndrome poses a risk to human health.
The Service also asks scientists and cavers to decontaminate clothing and equipment, following a standard protocol, once they leave a cave or mine to avoid spreading fungal spores. Scientists have worked with the agency to develop and continually refine recommended decontamination procedures.
Meanwhile, the Service has led the development of a national strategy to fight white-nose syndrome, setting priorities for surveillance, monitoring and mitigation. Along with nonprofit groups such as Bat Conservation International and the National Speleological Society, it has also devoted millions of dollars to related research. Such collaboration may represent the best hope of sustaining viable bat populations.
Little brown bats (Myotis lucifugus) in Trigg County, Kentucky, show signs of white-nose syndrome. The species has been especially hard hit by the fungal disease. Photo: Terry Derting/KDFWR.
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Author: Jennifer Koches, 843-727-4707 ext. 214, Jennifer_Koches@fws.gov
Contact: Ann Froschauer, National White-Nose Syndrome Communications Leader, U.S. Fish and Wildlife Service, 413-253-8356, Ann_Froschauer@fws.gov