The little brown myotis is a small bat with long, glossy fur that ranges in color from pale tan to dark chocolate brown. It is found in wooded areas throughout most of Canada and the northern half of the U.S., with the exception of desert or arid areas.

There are also a few isolated populations farther south. In summer, females often form nursery colonies in buildings. Nursery colonies have also been found in tree hollows, rock crevices and bridges. These bats are also common residents of bat houses. In winter, little brown bats hibernate in caves and mines.

The big brown bat is a relatively large, robust bat with a broad nose and fur that ranges in color from light rusty to dark chocolate brown. It ranges throughout most of the U.S. and Canada, with the exception of central Texas and extreme southern Florida.

In summer, females typically form nursery colonies of 25 to 75 bats, while males live alone or in smaller bachelor colonies. They commonly roost in buildings, although nursery colonies are also found in hollow trees. In winter, big brown bats hibernate singly or in groups of up to 100 in caves, abandoned mines and buildings.

The pallid bat is a medium-sized bat with light brown or grey-yellow fur with a white underside and large ears measuring about 25 mm (1 inch) in length. It is found in the western and southwestern U.S., mostly in arid areas. These bats roosts in caves, rock crevices, mines, hollow trees, buildings and under bridges.

The California myotis is a small bat that ranges in color from light tan to nearly black. It ranges from southern Alaska to western Canada southward through the western U.S. These bats roost under loose bark, in hollow trees, rock crevices and buildings. They also use bat houses. The sexes separate in the summer when females form small maternity colonies. California myotis hibernate in caves and mines.

The western long-eared myotis is a medium-sized bat with long black ears and dark wing membranes. The fur is long and glossy and generally brown in color. It ranges from southwestern Canada into the western U.S. and Baja California. These bats often live alone or in small groups, although females form small maternity colonies of 12 to 30 individuals in the summer. Western long-eared myotis roost in hollow trees, under loose slabs of bark, in fissures of cliffs, sink holes, caves, mines and abandoned buildings. They are also known to use bat houses. Measurements: forearm length 36-41 mm (1.4-1.6 inches), weight 5-8 grams (0.2-0.3 ounces).

The Yuma myotis is a small bat that ranges in color from light tan to dark brown with white under-parts. It ranges from southwestern British Columbia through the western U.S. In summer, females form maternity colonies that may include thousands of individuals. Maternity colonies are found in buildings, under bridges and in mines and caves. Males live relatively solitary lives, roosting in buildings or other suitable roosts. Yuma myotis also use bat houses. Bats leave the nursery roosts in the fall, although their winter habitat is unknown.

Rafinesque’s big-eared bat is a medium-sized gray bat with a white underside. It has large ears measuring more than 1 inch in length, and two large lumps on the snout. It occurs in the Ohio River Valley, and east and south of the Appalachians, westward along the Gulf Coast. Females form maternity colonies of up to several dozen individuals in building and sometimes in caves. Males roost singly during this time in buildings, behind loose tree bark and in hollow trees. They generally hibernate in caves or abandoned mines.