The northern long-eared bat is a medium-sized bat with a body length of 3 to 3.7 inches, but a wingspan of 9 to 10 inches. It is listed as a threatened species under the Endangered Species Act by the US Fish and Wildlife Service. - The northern long-eared bat is a medium-sized bat with a body length of 3 to 3.7 inches, but a wingspan of 9 to 10 inches. It is listed as a threatened species under the Endangered Species Act by the US Fish and Wildlife Service.