The world's only true flying mammals also are among its most misunderstood. Here are a few facts about bats:

• There are 1,100 known species of bats, accounting for about 20 percent of the world's mammal species.

• Pennsylvania is home to nine bat species: little brown bats, northern long-eared bats, Indiana bats, small-footed bats, silver-haired bats, Eastern pipistrelles, big brown bats, red bats and hoary bats.

• Little brown bats are the state's most common and can live up to 30 years. Females bear one pup per year, and mother bats recognize their young by smell.

• Little brown bats can eat up to 1,200 insects in a single hunting flight, and nursing females can eat the equivalent of their own body weight (about a half ounce) in a single night.

• Bats hibernate in the winter. In fall, winter and early spring, insects are not readily available to bats in Pennsylvania and other northern states. At this time, three species migrate south; six others hibernate underground, usually in caves.

• According to the state Department of Health, an average of 36 bats per year are found to be rabid in Pennsylvania, often with human exposure.

• More than 70 percent of bat species, including all of those found in the United States and Canada, dine on insects. About 24 percent of bats feed on fruit, and another three percent eat nectar. The remaining species feed on frogs, mice, birds or blood.

• There are only three species of hematophagic, or "vampire," bats. All are native to Latin America: the common vampire bat, the hairy-legged vampire bat and the white-winged vampire bat. These animals prefer to feed on sleeping livestock, but occasionally bite humans.

• The largest known bat is the giant golden-crowned flying-fox, a fruit bat that grows to about 2.6 pounds and boasts a 5-foot wingspan. It is found in the Philippines.

From the Pennsylvania Game Commission, Bat Conservation International and other sources.