Nine species of bats live at least part of the year in the northeastern United States, and two southern species reside infrequently in Pennsylvania. (See box.) Northeastern bats range in size from the hoary bat (length 5.1 to 5.9 inches from nose to tail; wingspan 14.6 to 16.4 inches; weight 0.88 to 1.58 ounces) to the pipistrelle bat (length 2.9 to 3.5 inches; wingspan 8.1 to 10.1 inches; weight 0.14 to 0.25 ounces). Colors range from the drab brown of the little brown bat to the striking frosted red coat of the red bat.
Although some mammals are able to glide, bats are the only mammals that truly fly. That is, they actually flap their wings to propel them in flight. They belong to their own unique order of mammals, called Chiroptera, meaning
