Eastern small-footed bats are the smallest of all the bats in their genus. They weigh 3.5 to 6 grams and are 75 to 85 mm long. Their wing span is 210 to 250 mm. They get their name because their feet are only 9 mm long, smaller than bats closely related to them. Males and females are similar in color and size. Their fur has black roots and shiny brown tips, so they look shiny yellowish-brown. Their underside is dull grayish-brown. Eastern small-footed bats have have a completely black face mask, black ears and wings. Their legs and tails are connected by stretched skin supported by a flap on their back leg. They also have a pointed piece of skin sticking out from thier ear about 9 mm in long. Their skulls are flat, short, and fragile. Their dental formula is: incisors 2/3, canines 1/1, premolars 3/3, and molars 3/3. Unlike similar species, their forehead slopes gradually away from their snout. Their ears stand up straight and their noses are flat. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007)
Eastern small-footed bats are often confused with two other kinds of bats: little brown myotis and tri-colored bats. Little brown myotis are larger than eastern small-footed bats. They don't have the black mask or extra skin on their back leg. Tri-colored bats have a more skin flap in their ear, pink on the front part of their arms, and no extra skin on their back leg. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007)
Eastern small-footed bats are native to the United States and Canada, but are one of the rarest bats in North America. They are found as far north as Ontario, as far south as Georgia, and as far west as Oklahoma. They live in the Ozark Mountains in Arkansas, Missouri and Oklahoma. They live in the Appalachian mountains in New England up to southeastern Canada. In the more southern states where they live, eastern small-footed bats are limited to caves and rocky outcrops. This happens in Virginia, North Carolina, South Carolina, Tennessee, Kentucky, Alabama, and northern Georgia. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007; Linzey, 1998)
Eastern small-footed bats roost during the spring and summer in buildings, bridges, caves, mines, hollow trees, tunnels, rock crevices, under rocks, and in rocky outcrops. In the winter, they hibernate in colder and drier spots than similar bats. Often, they choose the coldest part of a cave to hibernate. They prefer short caves (often less than 150 meters long) and return to the same spot every year. Almost all of their habitat (90%) is on private land which means it is difficult to protect their habitat. Only 3.8% of U.S. Forest service forests has the right habitat for them. They live at an elevation of 750 m in Virginia and 300-750 m in Pennsylvania. ("Conservation Assessments for Five Forest Bats Species in the Eastern United States", 2006; "Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007; Johnson and Gates, 2008; Veilleux, 2007)
In the late summer through early fall, many eastern small-footed bats gather together in the same spot. This is important for breeding and for choosing locations to hibernate. Both males and females have multiple mates. (Best and Jennings, 1997; Johnson and Gates, 2007)
Females usually give birth once a year, sometime between May and July. Mating is usually in late summer or fall but occasionally happens in winter instead. Scientists don't know much about their breeding behavior, but they are often found in large groups of mostly females when they give birth. These are called maternity colonies. Maternity colonies have been found in New Hampshire, Kentucky, North Carolina, South Carolina, and Ontario. They were found in rock crevices, guardrails on a concrete bridge, behind shed doors, and in wood piles and picnic shelters. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007; O'Keefe and LaVoie, 2011; Wimsatt, 1945)
When they are born, eastern small-footed bats weigh 20 to 35% of their mother's weight. This is large for a newborn baby, so the mother only has one at a time. This is probably because it would be too hard to get enough food for more than one baby at the same time. Males and females are the same size when they are born. After the young are born, the mothers go out foraging for food. They leave their babies in the sunniest spot they can find so the babies stay warm while they wait for food. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007; O'Keefe and LaVoie, 2011; Wimsatt, 1945)
Only female eastern small-footed bats care for newborns. They go out foraging for food, feed, protect, and teach their young. Mothers leave the newborn soon after birth to look for food. Scientists don't know how long it takes until the babies can eat foods besides milk. (Best and Jennings, 1997; Wimsatt, 1945)
Eastern small-footed bats live about 6 to 12 years in the wild. This depends on predators, habitat availability, and parasites or fungi. In captivity, the maximum recorded lifespan is 12 years. In northern parts of their range, males are more likely to survive than females. The survival rate for males is 75% and the survival rate for females is 42%. This might be because females have to use more energy during the reproduction process. Females who are pregnant or nursing also use more energy to stay warm if they aren't in a maternity colony. ("Conservation Assessments for Five Forest Bats Species in the Eastern United States", 2006; Best and Jennings, 1997; Hitchcock, et al., 1984)
Eastern small-footed bats are nocturnal, so they roost during the day and are active at night. In the summer, they leave their roosting site at dusk and fly around caves and open fields. Their flying height varies from 0.3 to 6.0 m. They fly slower than other small bats with a fluttering motion. They have a very strong homing instinct, and return to the same cave to hibernate even if moved to a different location. They do not migrate, but often change their roosting locations every day. This means they need lots of good roosting locations in their home range. Males and females have different roosting preferences. Their preferences change during the reproductive season, when females seek out warm sunny spots. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007)
Eastern small-footed bats hibernate during the winter. They are the last species in their range to hibernate in mid-November and the first to get up in March. They usually hibernate alone, but sometimes in groups. They spend most of their lives upside down, but hibernate horizontally and sometimes on cave floors. Because they are so small, they can squeeze into cracks and crevices to hide from predators. They usually hibernate near the entrances of caves shorter than 150 m long. They are able to drop their body temperature very low to hibernate in below freezing temperatures. In this process, they use 95% less energy than they normally would. They wake from this deep hibernation more often than similar species, so they can use up stored energy fairly quickly. Even though this uses a lot of energy, scientists think waking up is good for their immune system. During the time they hibernate between December and April, they lose about 16% of their body mass. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Best and Jennings, 1997; Chapman, 2007)
Eastern small-footed bats have been recorded moving a maximum of 1.1 km within their home range. (Best and Jennings, 1997)
Eastern small-footed bats find prey by sound using echolocation. When searching for insects, they use a search-phase call. While pursuing insects, they use an approach-phase call. Right before they are about to eat they prey, they make a terminal-phase call or feeding buzz. These calls are used to identify the location of the insect and to follow it. Calls last 2.8 to 5 milliseconds and their frequency ranges from 46.1 to 84.5 KHz. (Chapman, 2007; Murray, et al., 2001; Parsons, et al., 1997)
Eastern small footed bats are insectivores that mostly eat nocturnal flying insects. Their prey include beetles, mosquitos, moths, and flies. Occasionally they feed on ants too. They most often eat moths, but they eat a large variety of insects. When hunting for food, they fly about 1 to 3 meters off the ground. They often feed over water where there are lots of nocturnal insects. Sometimes, they fill their stomachs within one short hour. Other times they feed in dense forests. In the forest they eat insects from plants, rocks, or other surfaces. ("Conservation Assessments for Five Forest Bats Species in the Eastern United States", 2006; "Notes on Foraging Activity of Female Myotis leibii in Maryland", 2009; Johnson and Gates, 2007; Norberg and Rayner, 1987)
During the summer months, eastern small footed bats are found in cracks and crevices which reduce the chance of predation. Scientists do not know much about their specific predators. On the other hand, bats are often eaten by hawks and owls, snakes, raccoons, and weasels. ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011)
Eastern small footed bats have skin parasites that include mites called Androlaelaps casalis and Cryptonyssus desultorius, chiggers and ticks. Females that are all together during breeding more often get infected. Females in northern regions of the United States are more likely to be infected by the parasite Trypanosoma. This infection comes from the bat bug, which is common among female breeding groups in Ontario, Canada. Finally, they are prone to deadly white-nose syndrome caused by a fungus. (Gikas, et al., 2011; Hitchcock, et al., 1984; Timpone, et al., 2011)
Bats can carry rabies, which is deadly to humans. Eastern small-footed bats are suspected to be a rabies carrier. They may also carry Histoplasmosis, a disease caused by a fungus. In addition, they may be considered a nuisance because they roost in human structures. ("Current Status and Conservation Strategy for the Eastern Small-footed Myotis", 2001; Best and Jennings, 1997)
Eastern small footed bats prey on beetles and mosquitoes which are pests to humans and agriculture. ("Current Status and Conservation Strategy for the Eastern Small-footed Myotis", 2001; Jones, et al., 2009)
They are threatened by human activities because they need forest habitat. Logging, farming, and building more buildings shrinks their habitat. Drillling and mining for oil, gas, and minerals can destroy roosting sites and contaminate streams. In 2009, eastern small-footed bats were added to many conservation lists. They are listed as "critically imperiled" in 12 states, "imperiled" in 4 states, of "special concern" in 13 states, and "threatened" in 2 states. They are listed as "special concern" by the United States government and under review by the Endangered Species Act. The state of Michigan gives no special status and the IUCN Red List lists them as "least concern." ("Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat", 2011; Terwilliger, 1991)
Like many North American bats, eastern small-footed bats are threatened by a disease called “white-nose syndrome,” where a fungus grows on their noses while they are hibernating. This causes the bats wake up from hibernation and use up all of their energy resources. It has killed many bat populations since it was discovered in 2007. At some hibernation locations, as many as 90% of bats have died from the fungus. (Cryan, 2010; National Park Service, Wildlife Health Center, 2012)
Fossils were discovered in the Cumberland Cave in Maryland in 1972 and Big Bone Cave in Tennessee in 1975. These discoveries inspired scientists to research them more closely. Fossils of their close relatives were discovered in Arkansas caves in 1908 that were from the middle to late Pleistocene era (11,700 to 781,000 years ago). Eastern small-footed bats were previously thought to be a subspecies of western small-footed bats <<Myotis ciliolabrum>>. However, genetic analysis showed it is actually a separate species. (Best and Jennings, 1997; Linzey, 1998)
Victoria Scott (author), Radford University, Karen Powers (editor), Radford University, Kiersten Newtoff (editor), Radford University, Melissa Whistleman (editor), Radford University, Catherine Kent (editor), Special Projects.
United States Department of Agriculture. Conservation Assessments for Five Forest Bats Species in the Eastern United States. NC-260. Washington, D.C.: USDA Forest Service. 2006.
Virginia Department of Conservation and Recreation. Current Status and Conservation Strategy for the Eastern Small-footed Myotis. 00-19. Richmond, VA: Division of Natural Heritage. 2001.
U.S. Fish and Wildlife Service. Federal register notice of a 90-day finding for Eastern Small-footed bat and Northern Long-eared bat. FWS–R5–ES–2011–0024; MO 92210–0–0008. Pennsylvania: U.S. Fish and Wildlife Service. 2011.
Massachusetts Department of Fisheries and Wildlife. Homeowners Guide to Bats. 60521. Westboro, Ma: Massachusetts Department of Fisheries and Wildlife. 2009.
United States Department of Agriculture. Notes on Foraging Activity of Female Myotis leibii in Maryland. NRS-8. Delaware, OH: U.S. Forest Service. 2009.
Best, T., J. Jennings. 1997. Myotis leibii. Mammalian Species, 547: 1-6.
Chapman, B. 2007. The Land Manager's Guide to Mammals of the South. Durham, NC: The Nature Conservancy.
Cryan, P. 2010. "White-nose syndrome threatens the survival of hibernating bats in North America" (On-line). U.S. Geological Survey, Fort Collins Science Center. Accessed September 20, 2012 at http://www.fort.usgs.gov/WNS/.
Gikas, N., A. Zurcher, B. Walters, J. Whitaker. 2009. The first records of the eastern small-footed bat (Myotis leibii) in Indiana. Proceedings of the Indiana Academy of Sciences, 118/2: 203-204.
Gikas, N., D. Sparks, J. Whitaker, J. Johnson. 2011. New ectoparasite records for bats in West Virginia and a review of previous records. Northeastern Naturalist, 18/4: 527-533.
Harvey, M., S. Altenbach, T. Best. 2011. Bats of the United States and Canada. China: John Hopkins University Press.
Hitchcock, H., R. Keen, A. Kurta. 1984. Survival rates of Myotis leibii and Eptesicus fuscus in southeastern Ontario.. Journal of Mammalogy, 65/1: 126-130.
Johnson, J., J. Kiser, K. Watrous, T. Peterson. 2011. Day roosts of Myotis leibii in the Appalachian Ridge and Valley of West Virginia. Northeastern Naturalist, 18/1: 95-106.
Johnson, J., E. Gates. 2008. Spring migration and roost selection of female Myotis leibii in Maryland. Northeastern Naturalist, 15/3: 453-460.
Johnson, J., J. Gates. 2007. Food habits of Myotis leibii during fall swarming in West Virginia. Northeastern Naturalist, 14/3: 317-322.
Jones, G., D. Jacobs, T. Kunz, M. Willig, P. Racey. 2009. Carpe noctem: the importance of bats as bioindicators. Endangered Species Research, 8: 93-115.
Linzey, D. 1998. The Mammals of Virginia. Blacksburg, Virginia: McDonald and Woodward Publishing Company.
Merritt, J. 1987. Guide to the Mammals of Pennsylvania. Pittsburgh: University of Pittsburgh Press.
Moosman, P., H. Thomas, J. Veilleux. 2007. Food habits of Eastern Small-footed bats (Myotis leibii) in New Hampshire. American Midland Naturalist, 158/2: 354-360.
Murray, K., E. Britzke, L. Robbins. 2001. Variation in search-phase call of bats. Journal of Mammalogy, 82/3: 728-737.
National Park Service, Wildlife Health Center, 2012. "White-Nose Syndrome" (On-line). Accessed September 20, 2012 at http://www.nature.nps.gov/biology/WNS/index.cfm.
Norberg, U., J. Rayner. 1987. Ecological morphology and flight in bats (Mammalia; Chiroptera): wing adaptations, flight performance, foraging strategy and echolocation. The Royal Society: Biological Sciences, 316/1179: 335-427.
O'Keefe, J., M. LaVoie. 2011. Maternity colony of eastern small-footed myotis (Myotis leibii) in a historic building. Southeastern Naturalist, 10/2: 381-383.
Parsons, S., W. Thorpe, S. Dawson. 1997. Echolocation of the long tailed bat: a quantitative analysis of types of calls. Journal of Mammalogy, 78/3: 964-976.
Roble, S. 2004. Notes on an autumn roost of an eastern small-footed bat (Myotis leibii). Banisteria, 23: 42-44.
Rodriquez, R., L. Ammerman. 2004. Mitochondrial DNA divergence does not reflect morphological difference between Myotis californicus and Myotis ciliolabrum. Journal of Mammalogy, 85/5: 842-851.
Schwartz, C., E. Schwartz. 2001. The Wild Mammals of Missouri (2nd edition). Canada: Curators of the University of Missouri.
Terwilliger, K. 1991. Virginia's Endangered Species. Blacksburg, Virginia: The McDonald and Woodward Publishing Company.
Timpone, J., K. Francl, D. Sparks, V. Brack, J. Beverly. 2011. Bats of the Cumberland Plateau and Ridge and Valley Provinces, Virginia. Southeastern Naturalist, 10/3: 515-528.
Veilleux, J. 2007. A noteworthy hibernation record of Myotis leibii (eastern small-footed bat) in Massachusetts. Northeastern Naturalist, 14/3: 501-502.
Wimsatt, W. 1945. Notes on breeding behavior, pregnancy, and parturition in some Vespertilionid bats of the eastern United States. Journal of Mammalogy, 26/1: 23-33.