There is a serious epidemic that is impacting many bat species in the eastern United States. White nose syndrome is fatal to bats and is responsible for decimating approximately 1 million bats (thus far) as it makes its assault across much of the country. The syndrome was first discovered in a New York cave in 2006, and has rapidly spread.
One of the species of bats that is NOT significantly effected is the Big Brown Bat. Often, this bat prefers to hibernate above ground and these bats located in SE Michigan hibernate in houses. In fact, the largest colony of Big Brown Bats found in a Michigan mine numbered 225. This habit has saved this species from significant effects of the disease because houses are not likely to support the cause of the disease. In fact, the Big Brown Bat is still thriving in many areas where the disease was first discovered.
White Nose Syndrome is thought to be caused by a newly discovered cold loving fungus aptly named Geomyces destructans. The name foreshadows scientists anticipated impact to bats, and describes the urgency of the problem. The fungus thrives on hibernating bats in cold damp caves that have a humidity >90% and a temperature between 40-50F. The fungus establishes itself on the bats as they lower their body temperature during torpor. Bats use this semi-hibernation strategy to survive periods when food is not readily available. By reducing their body temperature, they can conserve energy and survive long periods by utilizing stored fat reserves. Unfortunately, the fungus appears to cause stress on the animal causing it to deplete these reserves at a quicker pace. Once the bat is sufficiently impacted, it attempts to fly out of the cave in search of food that isn’t readily available. One of the first signs, to the public, that the bats have been affected is observation of large numbers of bats flying during the daylight or near the mouth of a cave or mine.
Michigan DNRE anticipates placing the Little Brown Bat on the endangered species list, adding to the urgency of the matter.
Authorities are looking for instances where:
• Large numbers of sick or dead bats are observed near an opening of a cave or mine
• Bats are observed flying during the day (outside), in the middle of the winter.
• Hibernating bats with white fungus on the face or wings observed during winter.