Beginning in late fall, bats spend up to six cold months hibernating, and their body temperature drops to a crisp 45 to 55 degrees. For a brief period once every two weeks, however, they heat up to a typical mammalian range of 98 to 100 degrees. About 98 percent of the energy they will burn over the winter months, Verant said, will be devoted to these quick, hot blips. As bats hang from cold rock walls, saving enough energy to last the entire hibernation becomes a balancing act. (It's also why bat researchers are incredibly careful to disturb the mammals as little as possible in the colder weather.) And when fungus enters the fray, bats teeter over the edge.
They may be fragile in their winter slumber, but once warmer weather arrives, bats are pest-munching machines. And they don't need utility belts to be nocturnal superheroes: A little brown bat, no bigger than the size of a tightly closed fist, can eat up to 5,000 bugs in one night, Verant said.
In the northeast, bat populations have declined by as much as 80 percent. If North America were to lose all its bats, the effect would be catastrophic. A 2011 study estimated that bats prevent, at the very least, $3.7 billion in agricultural damage every year.