New York Natural Heritage Program
Little Brown Bat
Myotis lucifugus (Le Conte, 1831)

General Description [-]
The little brown myotis has glossy fur that may range from golden brown to cinnamon brown in color and buffy to pale gray below (Fenton and Barclay 1980; Hall 1981). When pressed forward, their ears reach approximately to their nostrils and their tragus, the fleshy protuberance in the outer ear, is approximately half the height of their ear (Fenton and Barclay 1980; Hall 1981). They typically weigh 7-14 grams, with females slightly larger than males (Harvey et al. 2011).

Identifying Characteristics [-]
The little brown myotis appears very similar to the Indiana bat (Myotis sodalis) but they have longer hairs on their feet that extend beyond their toes and they lack a keeled calcar, the spur of cartilage that occurs on the ankle joint (Fenton and Barclay 1980; Hall 1981:198). Northern bats (Myotis septentrionalis) have longer ears that extend beyond the nose when pressed forward, and a sharply pointed tragus, (Fenton and Barclay 1980). Little brown myotis are difficult to distinguish from other Myotis species in flight.

Best Life Stage for Proper Identification [-]
Adults may be easiest to identify.

Behavior [-]
The little brown myotis, like most bats, breed in the late summer to early fall; they swarm and mate near the cave or mine entrance. Breeding during swarming may result in mixture of genetics among groups from different areas since bats may travel to swarm near a cave or mine that they do not select to hibernate in over the winter (Carmody et al. 1971; Fenton and Barclay 1980). Ovulation occurs in the spring which coincides with emergence from winter hibernacula. Females give birth to one young approximately 50-60 days later (Wimsatt 1945; Fenton and Barclay 1980). Young are weaned and can fly after 21-28 days (Saunders 1988).

Little brown myotis are nocturnal with periods of heightened activity at pre-dawn and dusk. They maintain large home ranges to meet their daily energy and resting needs. Mean foraging ranges were 515 ha in Mississippi (Bergeson et al. 2013). During summer, females form large maternity colonies, while males and non-reproductive females may roost individually or in small groups and may use torpor to balance energy needs (Fenton and Barclay 1980). During winter, both genders roost together in large groups.

Communications for the little brown myotis are known to include echolocations (high frequency sounds used to communicate, navigate, and locate prey), vocalizations termed "honking" that are produced prior to an aerial-collision, isolation calls by young that aid in mother-young recognition, and chemical signals produced in the nasal glands that play a primary role in communication (Saunders 1988).

Little brown myotis are short-distance migrants but they may travel several hundred kilometers between hibernacula and summer colonies (Davis and Hitchcock 1965; Griffin 1970) which is farther than for some other myotis species. In Manitoba and northwestern Ontario, migration distances ranged from 10 to 647 km (Norquay et al. 2013) and in New York and New England up to 277 km (Davis and Hitchcock 1965). Site fidelity to summer colonies and winter hibernacula is common (Norquay et al. 2013). However for individuals that do relocate between hibernacula, females may be more likely to switch sites than males (Norquay et al. 2013).

Diet [-]
The little brown myotis is an insectivore that consumes a wide variety of insect orders. There are no known studies on their specific diet in New York, however, there are several from the eastern U.S. and they suggest regional differences in the variety and types of prey consumed. Coleoptera, Lepidoptera, and Diptera are important in the diets of little brown myotis across New England, with other groups consumed opportunistically (Moosman Jr et al. 2012). They are also known to prey heavily on the adult stages of aquatic invertebrates such as chironomids in northern parts of their range (Belwood and Fenton 1976; Anthony and Kunz 1977; Fenton and Barclay 1980). In WV, little brown bats consumed 10-22% each in descending order of importance of Lepidoptera, Diptera, Tricoptera, Coleoptera, Hymenoptera, Homoptera, and lesser amounts of Hemiptera (Carter et al. 2003). In Illinois, little browns consumed similar families, however Hymenoptera and Hemiptera were absent from their diet, and Aranea was added (Feldhamer et al. 2009).
The Best Time to See
The best time to see this species is from May through August in the early evening; however, it may be difficult to distinguish it from other Myotis species.
Present Active Reproducing
The time of year you would expect to find Little Brown Bat present (blue shading), active (green shading) and reproducing (orange shading) in New York.
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