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Myotis leibii (Audubon and Bachman, 1842)
Eastern Small-footed Bat
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G4
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 31
Habitat Summary for element in Georgia: Caves; mines; abandoned buildings, bridges, rock shelters in Mtn. areas; high elevation talus fields
Very small bat with golden-brown on back and grayish fur on the belly; glossy fur. Hair black at roots. The face is black, resembling a mask. The ears and wings are also black, which contrasts the brown body fur. Tragus is narrow and pointed and calcar is keeled. Feet are very small. This is the smallest Myotis species in Georgia. Total length is 75 – 85 mm (2.9 – 3.3 in), the average body length (excluding tail) of 40 - 50 mm (1.5 – 1.9 in), tail (base to tip of tail) of 33 – 40 mm (1.3 – 1.5 in), hind foot (ankle to tip of claw) 6 – 8 mm (0.2 – 0.3 in), ear of 12 – 15 mm (0.5 – 0.6), mass of 3 – 6 g (0.10 – 0.2 oz), and forearm length (outer edge of elbow to wrist) of 30 - 34 mm (1.2 – 1.3 in).
The eastern small-footed myotis is easy to distinguish from other similar Myotis species based on size, given that this bat is the smallest member of its genus in Georgia. The forearm and weight is less than that of any other Myotis species. It is also the only species with a black face mask. The tri-colored bat (Perimyotis subflavus) is similar in size but has a pale face and ears, pinkish forearms, and no black mask on its face. The little brown bat (Myotis lucifugus) is similar in coloration but does not possess as dark of a mask, has a longer forearm and hind foot length (34 – 41 mm, 1.3 – 1.6 in, and 8 – 10 mm, 0.3 – 0.4 in respectively), and does not have a keeled calcar. The Indiana bat (Myotis sodalis) may also be confused for the eastern small-footed myotis but has a pinkish face.
This species usually inhabits deciduous and coniferous (especially hemlock) forests, often at higher elevations (2000 feet). Summer roosts are typically in crevices of rocky outcrops and talus slopes and underneath rocks and tree bark, although some have been found in bridge expansion joints and buildings. Winter hibernacula include caves and mines, often hibernating near the entrances where temperatures can drop below freezing. They have also been found to hibernate in cracks in cave floors and under rock slabs.
The diet includes insects of the orders Lepidoptera (moths), Coleoptera (beetles), and Diptera (flies). Johnson et al.’s 2012 study reports that the eastern small footed myotis consumed eight orders of arthropods, but Lepidoptera was found at the highest volume and was consistently detected in all samples. Fecal samples of adult females contained a higher percent volume of Lepidoptera than samples of adult males. This study’s results provide evidence of moderate dietary specialization on Lepidoptera and indicates variation between sexes.
Swarming, breeding, and hibernacula selection occurs from late summer to early fall. Based on winter surveys, this species can hibernate individually or within small groups. Some studies have also shown that they tend to be more active in the winter than other cave dwelling bats. This is most likely due to their higher tolerance of lower temperatures, making them one of the last bats in the region to hibernate and one of the first species to emerge in spring. Sperm is stored during hibernation. Maternity colonies form in the spring and range from 12-33 individuals. Females typically give birth to one pup per year between May and July. Pups are born weighing 20-35% of their mother’s weight. Eastern small-footed myotis are estimated to live 6-12 years in the wild.
This species forages in a variety of habitats, including forested and open areas and is adapted to flying in dense vegetation. Individuals emerge at dusk to forage, and their flight is described as slow and erratic, usually 1 – 3 m above the ground. Johnson et al.’s 2009 study reports telemetered animals foraged within 1.8 km of their diurnal roosts and had home ranges of over 100 ha.
Conduct mist net surveys during the summer active months, but should follow guidelines laid out on our Bat Survey Guidance webpage (http://www.georgiawildlife.com/BatSurveyGuidance). Mist nets should be placed over water or on roads near optimal eastern small-footed myotis habitat. Cave surveys can be performed when absolutely necessary but should be limited as to prevent disturbances to all hibernating bats and limiting the spread of WNS. For more information on how to prevent the spread of WNS and how to decontaminate gear used during mist netting or cave surveys, see link this https://www.whitenosesyndrome.org/static-page/decontamination-information. Another common way to survey for eastern small-footed myotis is to look under rocks and within crevices in areas suitable for this species.
Native to the United States and Canada. Ranges from southern Ontario and extends southwest through the Appalachian Mountains, into eastern Oklahoma, to North Georgia, and as far west as Oklahoma. This species has only been found in the northern region of Georgia.
An emerging threat to this species is white-nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans. However, this species is less affected by this disease than other Myotis. This is most likely due to their tolerance of colder temperatures, often hibernating at cave entrances below the optimum temperatures needed for the growth of P. destructans. They are also more active during the winter months, allowing them to groom themselves more regularly, restore fat reserves, and rehydrate, possibly aiding in their survival against the effects of WNS. They are listed as “threatened” or “endangered” in many of the states within the eastern small-footed myotis range. Besides WNS, human activities, such as deforestation, agricultural and urban development, and wind turbines contribute to the decline of this species throughout its range.
Currently in Georgia the eastern small-footed myotis is a SWAP high priority mammal.
Protection of occupied caves and preservation and management of summer foraging habitat within the small-footed myotis range is recommended. Upland water sources and rocky talus slopes are also important to this species’ continued survival and should be preserved or restored.
Best, T.L. and J.B. Jennings. 1997. Myotis leibii. Mammalian Species no. 547 (1-6). American Society of Mammologists, New York.
Fenton, M.B., C.G. van Zyll de Jong, G.P. Bell, D.G. Campbell, and M. LaPlante. 1980.
Distribution, parturition dates, and feeding of bats in South-central British Columbia. Canadian Field Naturalist 94:416-420.
Harvey, M.J., J.S. Altenbach, and T.L. Best. 2011. Basts of the United States and Canada. Baltimore: Johns Hopkins University Press.
Johnson, J.S., J.D. Kiser, K.S. Watrous, and T.S. Peterson. 2011. Day-roosts of Myotis leibii in the Appalachian Ridge and Valley of West Virginia. Northeastern Naturalist. 18:96-106.
Johnson, J. B., J. E. Gates, and W. M. Ford. 2009. Notes on foraging activity of female Myotis leibii in Maryland [electronic resource]. Newton Square, PA: U.S. Dept. of Agriculture, Forest Service, Northern Research Station.
Johnson, J.S., L.E. Dodd, J.D. Kiser, T.S. Peterson, and K.S. Watrous. 2012. Food habits of Myotis leibii along a forested ridgetop in West Virginia. Northeastern Naturalist. 19:665- 672.
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.
O’keefe, J.M. and M. LaVoie. 2011. Maternity colony of eastern small-footed myotis (Myotis leibii) in a historic building. Southeastern Naturalist. 10:382-383.
Reid, F. A. 2006. Mammals of North America. Houghton Mifflin Company, New York.
Reynolds D.S., K. Shoemaker, S. Von Oettingen, and S. Najjar. 2017. High rates of winter activity and arousals in two New England bat species: Implications for a reduced white-nose syndrome impact? Winter Ecology: Insights from Biology and History Northeastern Naturalist. 24(Special Issue 7): B188-B208.
Species profiles: Myotis leibii. Bat Conservation international. Accessed on 9 Jan 2019 from http://www.batcon.org/resources/media-education/species-profiles/detail/2014.
Thomas, D.W., R.A. King, P. McKann, J. Szymanski, and L. Pruitt. 2012. Population-level impact of White-nose Syndrome on the endangered Indiana bat. Journal of Mammalogy. 93:1086-1098.
Kaitlyn Torrey
P. Sirajuddin. April. 2019. Edited format, grammar, and content
S. Thrasher. Aug. 2019. Edited
S. Krueger, March 2020. Edited for final review