Nature Guide: Big Brown Bat

Many people are afraid of bats, so it's no wonder they've become a scary symbol of Halloween. There's really no reason to be afraid, though. Bats rarely come into contact with humans. Also, they're important in controlling insects, many of which are pests. Our Nature Guide Jon Latimer gives us some more information about these creatures of the night.

"There are nine species of bats in New Jersey: three are migrants that fly south for the winter and six are here throughout the year. The Big Brown Bat (Eptesicus fuscus) is a year-round resident and the most common species in our area. Its body ranges up to 5 inches long and its wingspan to about 14 inches. It has copper-colored fur on its back and paler fur on its belly. Its wings are black but have no fur. It weighs only about half an ounce.

"Bats are the only mammals that fly and Big Brown Bats can fly up to 40 miles per hour. You are most likely to see them when they begin to hunt at dusk. They use echolocation to catch their prey in the dark, sending out high frequency sounds and listening for the echoes that bounce off nearly objects. Big Brown Bats can eat as many as 3,000 insects in a single night, including moths, flies, mosquitoes and especially flying beetles. They scoop up insects with their tail or wing membranes and place them in their mouth, which is why their flight pattern is so irregular.

"Big Brown Bats are social animals that hibernate in large numbers in caves and mines during winter. In spring they spread out and roost together in smaller colonies, often in buildings. They may return to the same roost year after year.

"A common concern about bats is that they spread rabies, but less than one percent of bats carry rabies and bites by bats are extremely rare. Another disease, called White-nose Syndrome, has killed tens of thousands of bats in North American. Named for a white fungus that appears around the noses of affected bats, this disease attacks them during winter hibernation. In 2010 New Jersey officials estimated that the state's bat population had declined by 90 percent. So far, no cure has been found."

Photos (click for a larger image): NPS, NPS, Tim Krynak/USFWS, Marvin Moriarty/USFWS