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The bat killer: White-Nose Syndrome

Arkansas Natural Heritage Commission - Friday, March 29, 2019

Reprinted with permission from Bats of Arkansas

(Perry, Roger M., Moore, P., Armstrong, K. and Robbins, L. Bats of Arkansas, Publication Number 8. Indiana State University Center for Bat Research, Outreach, and Conservation. 2018.)

During the early months of 2007, bats in upstate New York were behaving strangely – flying outside in daylight during the winter, even while it was snowing. When biologists visited four caves near Albany, they found bats hibernating near the cave entrances rather than farther inside the caves. Large numbers of dead and dying bats were inside and outside the caves, and many bats had a white fungus on their noses and wings. The dead and dying bats were emaciated and dehydrated. The condition was named White-Nose Syndrome (also called WNS). White-Nose Syndrome spread quickly through the Northeast, down the Appalachians, westward, and north into eastern Canada. In 2016, it appeared in the Pacific Northwest, and in 2017 in Texas. It has negatively impacted several bat species that hibernate in caves or mines – the little brown bat, Indiana bat, northern long-eared bat, eastern small-footed bat, southeastern myotis, tri-colored bat, and big brown bat. Alarmingly, mortality rates exceeding 90 percent have been reported at some hibernacula and over 6 million bats have already died from WNS. If White-Nose Syndrome continues to spread, even species of bats that are now common could become rare.

The actual cause of death appears to be starvation or dehydration before insects become available in spring. Death could also be caused by extensive wing damage that restricts the bats’ ability to forage when they emerge from hibernation. Researchers identified the fungus as a previously unknown species, Pseudogymnoascus destructans, which thrives in the cold, moist conditions that exist in caves. The low body temperatures and suppressed immune systems of hibernating bats make them susceptible to infection by the fungus. The fungus is transmitted from bat to bat through physical contact, but can also be spread from infected caves to bats. The fungus might also be inadvertently carried to new areas by humans on clothing, footwear, or caving equipment. Following its discovery in the United States, P. destructans was also found in Europe and Asia where it grows on some bats, but does not produce mass mortality. Thus, it appears that someone traveling from Eurasia inadvertently introduced the WNS fungus into North America.

At this time, there is no effective treatment for bats with White-Nose Syndrome or methods to eradicate P. destructans from caves and mines. Federal and state agencies have closed caves on federal lands to visitation in an effort to keep people from spreading the fungus, but it is impossible to prevent the movement of infected bats into new areas. Closures include most cave sites on National Forests and National Parks in Arkansas, although Blanchard Springs Caverns is still open for public visitation. Biologists entering hibernacula or handling bats during the summer are required to follow rigorous decontamination procedures to help prevent spread of the fungus. Much research is being devoted to learning more about the fungus and how it affects bats in the hope of finding ways to protect them from WNS.

As of 2018, WNS had affected bats in 34 states and seven Canadian provinces. Bats with WNS were first seen in Arkansas during the winter of 2012-2013. Infected bats have been found in caves throughout the Ozarks. Nine bat species in the state may be impacted to some extent by WNS because they hibernate in caves and mines. The big brown bat is a “cave bat,” but many individuals hibernate in buildings and they could escape infection by P. destructans. Eastern red, hoary, Mexican free-tailed, Seminole, silver-haired, and evening bats rarely enter caves or mines in Arkansas so these species may be safe from the ravages of White-Nose Syndrome.

Photos:

Top left -- A little brown bat (Myotis lucifugus) with White-Nose Syndrome. Photo by Marvin Moriarty, U.S. Fish and Wildlife Service.

Bottom -- An ANHC staff member utilizes UV light to check for White-Nose Syndrome, which illuminates under certain wavelengths of fluorescent light. Photo by Ozark Subterranea.



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