Gray Myotis (Gray Bat)

Photo of four gray myotises clinging to a cave ceiling.
Species of Conservation Concern
Scientific Name
Myotis grisescens
Vespertilionidae (evening bats) in the order Chiroptera

The gray myotis, or gray bat, is the largest of all Missouri’s myotis (mouse-eared) bats, which include the little brown myotis, the Indiana myotis, and the northern long-eared myotis. Gray myotises are hard to distinguish from their myotis cousins. Gray myotises have grayer fur; it is a uniform brownish gray most of the year, turning a light rusty brown in summer. Other myotises have bi- or tricolored fur, with the tips of each strand contrasting with the base. The gray myotis’s ears and wing membranes are gray to black. Its key identifying feature is wings that attach to the ankle and not at the base of the toes. The gray myotis also has a distinct notch on the inside curve of each claw.


Length: 3 inches; wingspan: 10-12 inches; weight: 1/3 ounce.

Where To Find
Gray Myotis, Gray Bat Distribution Map

Missouri contains about 20 percent of the total population of gray myotises. Most of the known gray myotis caves are south of the Missouri River, particularly in the Ozarks, although a few exist north of the river.

This species once flourished in limestone caves, especially caves within two miles of rivers, streams, or lakes. Conservation efforts include protecting known gray myotis wintering and nursery caves from disturbance, reducing the use of pesticides (which not only affect their prey but also accumulate in the bat's tissues and mother's milk), and maintaining wooded corridors along streams. White-nose syndrome, a deadly fungal disease, is a new and grave threat to this species' survival.

BATS AND COVID-19: There is no evidence that Missouri bats have COVID-19 (SARS-CoV02), the virus that is causing the human pandemic. All viruses that have been identified in U.S. bats are alphacoronaviruses, while COVID-19 is a betacoronavirus. MDC, the U.S. Fish and Wildlife Service, and the Association of Fish and Wildlife Agencies are concerned about the possibility of bats contracting the COVID-19 virus from infected humans. Until more information is available, no activities that result in the direct interaction with live wild bats or with MDC-owned caves are permitted under existing or new 2020 Wildlife Collector Permits at this time. To protect bats, people are advised to not interact with them.

Insects, including caddisflies, moths, stoneflies, mayflies, flying beetles, true flies, and moths. The Asiatic oak weevil is a favorite summertime food, when it is abundant in forested cliffs along rivers. Most insects are eaten on the wing.

Listed as Endangered by both the Missouri Department of Conservation and the U.S. Fish and Wildlife Service.

Life Cycle

Pregnant females roost in maternity colonies in caves separate from males and young females from late May to June. Each female gives birth to a single young in June. The young are able to fly 4 weeks later. Mothers and young rejoin the bachelor colonies in July and August. Gray myotises exhibit great loyalty to their roosting and hibernating sites and will return to the same caves year after year.

Bats eats untold numbers of flying insects. It is important for people to stay out of nursery caves: If disturbed, pregnant females may abort their young and babies may drop from the wall to the floor or stream below and die. A single disturbance can wreck a colony’s reproduction for the year.

Bats help control populations of flying insects. Their presence in caves is a crucial part of those unique underground ecosystems. By collecting organic material (insects) from outside the cave and bringing it in (as guano), bats help provide the basis for a variety of cave life forms.

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About Mammals in Missouri
More than 70 species of wild mammals live in Missouri: opossums; shrews and moles; bats; rabbits; woodchuck, squirrels, beaver, mice, voles, and other rodents; coyote, foxes, bear, raccoon, weasels, otter, mink, skunks, bobcat, and other carnivores; deer and elk; and more. Most of us recognize mammals easily — they have fur, are warm-blooded, nurse their young, and breathe air.