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Photo by: Phil Meyers, University of Michigan-Ann Arbor
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Myotis lucifugus (Le Conte, 1831)

Little Brown Myotis

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G3

State Rank: S1

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 23

Habitat Summary for element in Georgia: Caves and Mines; mixed forests, structures, bat houses


Description

The little brown myotis is a tan to dark brown bat with glossy fur on its back and gray to buff yellow on the ventral side with darker hairs at the root. Snout and ears are dark brown to blackish and it does not have a keeled calcar. It has medium-sized ears with a slightly curved and rounded / not sharply pointed tragus. Little brown bats have long toe hairs that extend past the tip of claw. Little brown bats have a body length (excluding tail) of 46 – 58 mm (1.8 – 2.3 in), tail (base to tip of tail) of 30 – 40 mm (1.2 – 1.6 in), hind foot (ankle to tip of claw) 8 – 10 mm (0.3 – 0.4 in), ear of 14 – 16 mm (0.5 – 0.6 in), mass of 7 – 9 g (0.2 – 0.4 oz), and forearm length (outer edge of elbow to wrist) of 34 - 41 mm (1.3  – 1.6 in).

Similar Species

This species is often confused with other Myotis spp such as the Indiana bat (Myotis sodalis) and northern long-eared bat (Myotis septentrionalis). M. sodalis has a keeled calcar, its toe hairs do not extend past the claws, which differs to the little brown bat. While, M. septentrionalis has longer ears that extend at least 3mm beyond tip of nose and has a longer and more pointed tragus as while the little brown bat’s ear typically does not extend past the nose when laid forward. The southeastern myotis (M. austroriparius) has brown – grayish, dull fur with a whiteish belly as compared to the little brown bat.

Habitat

Little brown bats typically roost in caves and mines in the winter, and they can be found in trees, man-made structures, bat houses, under rocks, and in piles of wood in the summer. Foraging is primarily done near water, and in a pattern around trees or houses.

Diet

Diet consists of flying insects including mosquitoes, moths, gnats, crane flies, small beetles, and spiders. However, the relative proportions of flying insects and terrestrial insects’ changes across the species geographic distribution. Shively et al.’s 2018 show that individuals in the extreme northwest region of their range consume more terrestrial insects, as flying insects are less available. Kaupas and Barclay’s 2017 study also suggest that the species wide and diverse prey selection has allowed for their broad geographic distribution.

Life History

In the spring, they emerge from their hibernacula to disperse to their summer ranges. Females begin to form maternity colonies, commonly in hot attics, that can consist of 2-100+ individuals. Females have also been found to roost in large trees during the maternity season. Males often roost under exfoliating bark, within tree trunks, and within tree cavities of live and dead trees during the summer. Males have also been observed roosting in man-made structures, such as barns, during the summer.

Large numbers of individuals may swarm around caves or mines in late summer and mating typically occurs in the fall; activity decreases with lower temperatures. Females store sperm during the winter, a process known as delayed fertilization. Females typically give birth to a single pup in May-June after  50 – 60 days of gestation. Lactation is energetically expensive during the summer and females lose the ability to thermoregulate. The young are able to fly in about four weeks. Bats of this species are known to live up to 30 years.

Survey Recommendations

Winter roost sites can be identified through knowledgeable cave exploration, but hibernating bats should not be disturbed. During summer, mist netting surveys in Georgia should follow guidelines laid out on our Bat Survey Guidance webpage (http://www.georgiawildlife.com/BatSurveyGuidance). Mist net and cave surveys (especially during winter months) should be done with care to prevent the spread of the causative fungus of white-nose syndrome (WNS). Avoid the spread of WNS by decontaminating all survey gear and clothing. (https://www.whitenosesyndrome.org/static-page/decontamination-information).

Range

This species in known to occur throughout the United States ranging from Alaska across Canada, south to Southern California, Northern Arizona, and Northern New Mexico (USA). Little brown bats are absent from much of Florida. It is more common in the northwest part of its range due to declines from disease and has only been documented in northern Georgia.

Threats

White-nose syndrome (WNS) is the largest threat to little brown bats. It was first observed in the United States in 2006 in New York, and has spread rapidly among bat populations. In the northeast, little brown bats have experienced severe population declines due to the disease. WNS was discovered in Georgia in 2013, and although this species was never abundantly common in the state, there have been noticeable declines in their numbers. Other threats to this species include habitat loss and mortality from wind turbine facilities.

Georgia Conservation Status

Little brown bats have suffered severe population declines across their range where WNS is present, including in Georgia. Therefore, this species is listed as endangered in the state of Georgia and is included in Georgia’s list of SWAP high priority mammals.

Conservation Management Recommendations

Protection of occupied caves is extremely important and disturbance to hibernating bats should be avoided. Forest management activities at summer roost sites should ensure that forested foraging habitat is available, that no known roost trees are destroyed, and that a continuous supply of suitable roost trees and clean water are available.

References

Broder H. G. 2010. Interspecific and intersexual variation in roost-site selection of northern long-eared and little brown bats in the Greater Fundy National Park ecosystem. Journal of Wildlife Management. 68: 602-610.

Fabianek, F., M. A. Simard, E. B. Racine, and A. Desrochers. 2015. Selection of roosting habitat by male Myotis bats in a boreal forest. Canadian Journal of Zoology. 93: 539-546.

Fenton, M., R. Barclay. 1980. Myotis lucifugus. Mammalian Species. 142: 1-8.

Harvey, M. W., J. S. Altenbach, and T. L. Best. 2011. Bats of the United States and Canada. The John Hopkins University Press, Baltimore.

Kaupus, L. A. And R. M. R. Barclay. 2018. Temperature-dependent consumption of spiders by little brown bats (Myotis lucifugus), but not northern long-eared bats (Myotis septentrionalis) in northern Canada. Canadian Journal of Zoology. 96(3):261-268

Kurta, A. and T.H. Kunz. 1988. Roost metabolic rate and body temperature of male little brown bats (Myotis lucifugus) in summer. Journal of Mammalogy. 69: 645-651.

Menzel, M. A., B. R. Chapman, W. M. Ford, J. M. Menzel, and J. Laerm. 2000. A review of the distribution and roosting ecology of bats in Georgia. Georgia Journal of Science 59: 143-178.

Morgan, C. N., L. K. Ammerman, K. D. Demere, J. B. Doty, Y. J. Nakazawa, and M. R. Mauldin. 2019. Field identification key and guide for bats of the United States of America. Museum of Texas Tech University.

NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org.

Olson C.R. and R.M.R. Barclay. 2013. Concurrent changes in group size and roost use by reproductive female little brown bats (Myotis lucifugus). Canadian Journal of Zoology. 91: 149-155.

Reid, F. A. 2006. Mammals of North America. Houghton Mifflin Company, New York.

Shively, R. P. Doak, P. Barboza, T. S. Jung, Increased diet breadth of little brown bats (Myotis lucifugus) at their northern range limit: a multi method approach. Canadian Journal of Zoology. 96(1):31-38

Authors of Account

Emily Ferrall

Date Compiled or Updated

Edited general formatting, description, range, life history, and literature.

Photo by: Laci Pattavina (GDNR)