Northern Myotis (Myotis septentrionalis) were formally named Myotis keenii.  These bats are found in eastern and northern North America, in dense forest stands along rivers and streams. They roost under tree bark or in tree cavities, while using caves and mines for hibernation. They hibernate alone or in small groups. They have very long ears up to one inch in length. From August until October, they increase their body weight 41-45% in preparation for hibernation. Northern myotis have one pup, which is born either in June or July. Northern mitosis began to forage just after sunset, and intermittently through out the night, then again, just before dawn. They have a slow flight.