Wisconsin's Bats

Little Brown Bat
(Myotis lucifugus)

This species is the most common Myotis species in the northern two-thirds of the U.S. Frequently found in tree hollows and

Illustration of a little brown bat
Little Brown Bat
chases a moth

buildings during the summer, it often roosts with big brown bats. In winter it flies to the nearest suitable cave or abandoned mine hibernate. This is the species most likely to be found in homes and usually occurs near rivers, lakes, or marshes.

Northern Myotis or Eastern Long-ear
(Myotis septentrionalis)

This species is similar in appearance to the little brown bat although its hair is somewhat duller and not as glossy. Not as abundant in Wisconsin as the little brown bat, the Eastern Long-ear prefers abandoned mines and small caves and seems less attracted to buildings. It, like the little brown, feeds on insects.

Big Brown Bat
(Eptesius fuscus)

This bat is larger than the little brown bat and one of the most common and widespread species of North America. It roosts in colonies in tree hollows, wall spaces, and buildings. More tolerant of cold conditions than other Wisconsin bats, it is the only one that commonly overwinters in walls and attics. It ranges in color from pale brown to dark brown with a black wing membrane. It hibernates in caves, abandoned mines, and sometimes in buildings.

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Silver-Haired Bat
(Lasionyceris noctivigans)

This species is black to dark brown with the dorsal fur frosted with silver. It lives in wooded areas of the U.S. and Canada and migrates south to central and southern states where it hibernates in rock crevices and tree hollows. It feeds in forest openings and along forest edges, apparently on a wide variety of insects.

Red Bat
(Lasiurus borealis)

Click to enlarge photo of red bat by Kathy Kirk
A small red bat hangs at the edge of woodland on a hot August day; photo by Kathy Kirk

The red bat is a solitary species found most often in deciduous tree foliage during the summer. It migrates south to the central and southern states where it probably hibernates in tree hollows. The red bat had angora-like red-orange to yellowish fur. It is often overlooked because it can appear, at quick glance, to be a dead leaf. Red bats are early fliers in the evening but are much faster in flight than pips. They are rarely seen far from forested areas. Moths are their preferred food. Triplets and even quadruplets are not uncommon.

Hoary Bat
(Lasiurus cinereus)

One of the largest bats in the U.S. and the most widely distributed, this species has dark-yellowish fur tipped with white, which gives it its name. It is more common in the prairie states than in the eastern U.S. It roosts in tree foliage, but mostly in evergreens. Like the red bat, it eats moths. Northern populations may migrate considerable distances to subtropical areas when the weather gets cold.

Eastern Pipistrelle
(Pipistrellus subflavus)

This species is Wisconsin's smallest with a body of three inches or less and a wingspan rarely exceeding seven inches. Pips, as they called, have a blunt tragus (tragus is a flap of skin at the base of the external ear) whereas all of our Myotis species have a pointed tragus. Pips emerge earlier in the evening than most other bats and have a rather slow erratic flight pattern. It is found in wooded areas of eastern North America.

Indiana Bat
(Myotis sodalis)

An endangered species protected by federal legislation. Very difficult to distinguish from other Myotis species. Indiana bats are colonial hibernates.

Last Revised: October 26 2004