Little Brown Myotis (Little Brown Bat)

Little brown bat held in a blue-gloved hand, grinning and doing “jazz hands”
Species of Conservation Concern
Scientific Name
Myotis lucifugus
Family
Vespertilionidae (evening bats) in the order Chiroptera
Description

The little brown myotis, or little brown bat, is a small bat with dark glossy brown fur on its back. Its populations are declining.

The fur on the back is two-toned: blackish or dark gray at the base and brown toward the tips. The overall look of the fur on the upper surface of the bat is from yellowish brown to olive brown; the glossy tips of the hairs give it a metallic sheen. The wing and tail membranes and the ears are glossy dark brown.

In addition to the coloration described above, note that the ears are ⅝ inch long or less and are narrow, naked, with bluntly rounded tips.

Similar species: Missouri has five other species of bats in genus Myotis:

  • Southeastern myotis (M. austroriparius)
  • Gray myotis (M. grisescens)
  • Eastern small-footed myotis (M. leibii)
  • Northern long-eared myotis (M. septentrionalis)
  • Indiana myotis (M. sodalis)

For more information about Missouri’s bats as a group, visit the Bats page.

Size

Total length: 76–95 mm (3–3¾ inches); tail length: 31–44 mm (1¼–1¾ inches); weight: 6–11 g (about 0.2–0.4 ounce); forearm length: 33–41 mm (about 1⅜–1⅝ inches); wingspan: 22–27 cm (about 8½–10½ inches).

Where To Find
Little Brown Myotis, LIttle Brown Bat Distribution Map

Widely distributed throughout the state but no longer common in any one place.

When feeding, little brown myotises prefer borders between open areas and denser cover where flying insects are plentiful, and they also frequently forage over water.

Little brown myotises hibernate, typically in small clusters of around 20 individuals, in limestone caves and mines, mostly in the Ozarks. In spring, they disperse up to 620 miles.

In spring and summer, the females live in nursery colonies in cliff crevices and hollow trees, under loose bark, in attics, and other undisturbed retreats. Males are solitary or live in colonies up to 20 in similar protected sites, including under siding and shingles. Males are less picky about the temperature of their roosting sites because they can enter torpor if the temperature drops. Pregnant or nursing females require warmer roosts to avoid interrupting the development of their fetus or pup.

Only insects are eaten, particularly winged adult forms in flight: mayflies, mosquitoes, midges, beetles, flies, caddis flies, lacewings, stone flies, and moths. Little brown bats feed heavily, consuming half their body weight in a night.

Bats use echolocation to locate and catch their prey. They emit ultrasonic cries too high for humans to hear, then listen for those sound waves to reflect from their prey’s body to determine its size, position, speed, and direction.

A species of conservation concern in Missouri, imperiled to extirpation from the state. Once common across the state, this species has declined dramatically across the eastern part of its range, including Missouri, resulting from impacts of white-nose syndrome.

No longer common in any one place; populations are declining. This is one of the species most heavily affected by white-nose syndrome, particularly in northeastern states.

In this species, mating is in fall before hibernation, during winter if bats become active, and in spring after hibernation. The ovum undergoes no change during winter, but in spring it is shed from the ovary and fertilization follows.

In nearly all cases, only a single young is produced annually. Most young are born by mid-June and are weaned in about 6 weeks. Young are most vulnerable during the first few weeks of life, especially if they fall from roosting sites and cannot be retrieved by their mothers.

In the wild, little brown myotises can live to be more than 30 years old.

Bat Control

Bats help control insects, some of which are agricultural pests or, like mosquitoes, are annoying or harmful to people.

Bats have contributed much to human knowledge through scientific studies of their echolocation, biology, and physiology.

Bats are protected by both state and federal laws.

Bats are one of the few kinds of mammals that people can enjoy watching, but they have suffered from misinformation and superstition for years.

As predators, bats help to hold insect populations in balance.

Many forms of cave-dwelling life depend on the nutrients brought in by bats and released from their guano (feces).

Bats are greatly important in the natural scheme of things. Without conservation, we may lose many bat species forever.

Media Gallery
Little brown bat held in a blue-gloved hand, grinning and doing “jazz hands”
Little brown bats feed on flying insects such as mayflies, mosquitoes, midges, beetles, flies, caddisflies, lacewings, stone flies, and moths.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
1/17
Little brown bats, small cluster plus one individual, clinging to a pocket in a cave
Little brown bats typically hibernate in groups smaller than those of Indiana bats or gray bats. The strong contrast between the color of their back, belly, and bare skin also helps distinguish them from those species.
MDC Staff
Photo by MDC Staff, courtesy Missouri Department of Conservation
2/17
Little brown myotis hanging from cave wall with lesions on its wrist
In winter, little brown myotises hibernate in Ozark caves and mines. In spring they disperse up to 620 miles. Females form nursery colonies in cliff crevices and hollow trees, under loose bark, in attics, and in other undisturbed retreats. Males live singly or in small colonies.
MDC staff
Photo by MDC staff, courtesy Missouri Department of Conservation
3/17
One little brown bat clinging to the wall of a cave
During autumn, a little brown bat will increase its body weight by about 30 percent in preparation for hibernation.
MDC Staff
Photo by MDC Staff, courtesy Missouri Department of Conservation
4/17
Three little brown bats clinging to the wall of a cave
Little brown bats typically mate in the fall. The sperm persists in the female’s reproductive tract until spring, when fertilization occurs. Pups are born from late May to early July.
Shelly Colatskie
Photo by Shelly Colatskie, courtesy Missouri Department of Conservation
5/17
Little brown bat held in a blue-gloved hand, hunkered down
The scientific name for the little brown bat is Myotis lucifugus. The genus name, Myotis, comes from two Greek words meaning “mouse” and “ear.” The species name, lucifugus, comes from Latin words meaning “light” and “to flee,” referring to their nocturnal behavior.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
6/17
Little brown bat held in a blue-gloved hand
Little brown bats have glossy brown fur on their back, paler bellies, and comparatively dark skin on their face, ears, and forearms.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
7/17
Little brown bat held in a blue-gloved hand, mouth open as if singing
Little brown bats have been known to live more than 30 years in the wild. Bats’ life spans are usually determined by recapturing individuals wearing bat bands like the one on this male’s right wing.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
8/17
Little brown bat held in a blue-gloved hand
Female little brown bats form maternity colonies in the summer. They typically roost underneath peeling bark or in tree cavities, but they also use structures like barns and attics.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
9/17
Little brown bat held in a blue-gloved hand, wing partially extended
Little brown bats are one of the most widely dispersed species in North America and were once one of the most common species of bat. However, they have been heavily impacted by White-Nose Syndrome, and genetic evidence suggests they may need to be reclassified as multiple species.
Kyle Jansky
Photo by Kyle Jansky, courtesy Missouri Department of Conservation
10/17
Photo of a little brown bat
Little brown myotis (little brown bat)
Use of this image is restricted to MDC only
11/17
researcher holds a little brown myotis
Once common across the state, the little brown myotis has declined dramatically across the eastern part of its range, including Missouri, resulting from impacts of white-nose syndrome.
MDC staff
Photo by MDC staff, courtesy Missouri Department of Conservation
12/17
White Nose Syndrome in Little Brown Bat
This photo from the U.S. Fish and Wildlife Service shows white-nose syndrome in a little brown myotis.
U.S. Fish and Wildlife Service
Use of this image is restricted to MDC only
13/17
brown bat with powdery white fungus on its nose shows signs of disease
A deadly disease in bats called white-nose syndrome was confirmed in three bats from two caves in Lincoln County in March 2012. The name describes the white fungus, Pseudogymnoascus destructans, shown on the face and wings of this infected little brown myotis.
U.S. Fish and Wildlife Service
Use of this image is restricted to MDC only
14/17
Little brown bats
Little brown bats (Myotis lucifugus) with white-nose syndrome.
Shelly Colatskie
Photo by Shelly Colatskie, courtesy Missouri Department of Conservation
15/17
Little brown bats with signs of WNS
Little brown bats (Myotis lucifugus) with white-nose syndrome.
Shelly Colatskie
Photo by Shelly Colatskie, courtesy Missouri Department of Conservation
16/17
Little Brown Bat
Little brown myotis (little brown bat), Myotis lucifugus.
Jim Rathert
Photo by Jim Rathert, courtesy Missouri Department of Conservation
17/17
Little brown bat held in a blue-gloved hand, grinning and doing “jazz hands”
Little brown bats, small cluster plus one individual, clinging to a pocket in a cave
Little brown myotis hanging from cave wall with lesions on its wrist
One little brown bat clinging to the wall of a cave
Three little brown bats clinging to the wall of a cave
Little brown bat held in a blue-gloved hand, hunkered down
Little brown bat held in a blue-gloved hand
Little brown bat held in a blue-gloved hand, mouth open as if singing
Little brown bat held in a blue-gloved hand
Little brown bat held in a blue-gloved hand, wing partially extended
Photo of a little brown bat
researcher holds a little brown myotis
White Nose Syndrome in Little Brown Bat
brown bat with powdery white fungus on its nose shows signs of disease
Little brown bats
Little brown bats with signs of WNS
Little Brown Bat
Similar Species
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.
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