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Scientists today confirmed that the fungus, Geomyces destructans, causes white nose syndrome, the deadly killer that has been wiping out cave-hibernating bats throughout the eastern United States.
A science team led by David Blehert of the National Wildlife Health Center in Madison, Wisconsin captured healthy little brown bats and infected them with the fungus while they were in hibernation, some by direct application and others by putting them in contact with already infected bats. After 102 days, all of the first group had developed white nose on their muzzles and wings, while 16 of 18 of the second group had become infected as well.
White nose syndrome is named after a newly discovered fungus that is seen on all affected bats, and has been the prime suspect for killing them, as it disturbs them during hibernation, causing them to wake more frequently, burn up their reserves,and thus starve to death. In the past five years the syndrome has killed about 90 percent of the bats in the northeastern United States. It first appeared in upstate New York, and has since spread south and then west, following bat migration patterns as they travel during the summer months. (While human activity might spread the syndrome as well, the evidence all points to the bats as the primary vector.)
Though this result is important, it shows once again how little we can do to stop the spread of white nose. The bats are going to pass it on no matter what we do. The only hope the bats have is that in warmer climates, the fungus will not be able to do harm, as it cannot grow on the bats except when the bat is in hibernation. Active and awake bats are simply too warm for the fungus to prosper, and in warmer climates bats do not need to hibernate because food is available year round.
In addition, the fungus does not seem capable of killing the bats by itself, as it requires the perfect circumstances (hibernation, cold weather, a shortage of food) to do its worst damage. For example, it has been found that if a bat comes out of hibernation early but is given food and water and placed in warm temperatures until its immune system can become active, the bats recover completely. “I call it bat magic,” explained Carol Meteyer, USGS wildlife pathologist. “After seven weeks of recovery the recovered bats cannot be distinguished from normal bats.”
Unfortunately, it is difficult if not impossible to capture and save most bats in this manner. The best biologists might do is to prevent extinction in colder climates is by housing a small number of bats temporarily. Bats in warm climates, however, would naturally be unaffected by the fungus, as it will not be able to grow on them in the first place.
Also, some species, such as the Virginia Big Ears bats, have not been affected by the syndrome. It is thought that because these bats prefer colder environments in caves they have been protected from the fungus, which seems to prefer different cave temperatures. It is also possible but not proven yet that some species might be resistant to the fungus.
The fungus is widespread in Europe, and it is believed that it was brought to the U.S. by accident, either by a stowaway bat or by a human tourist visiting the commercial cave, Howe Caverns, in New York. Why the bats in Europe have not killed by the fungus remains unknown and needs further research.