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Overview

Brief Summary

Description

The eastern small-footed myotis is one of the smallest North American bats. It has a limited range, occurring only in eastern deciduous and coniferous forests. This bat tolerates colder temperatures than many bats, entering hibernation later than many (November to December) and leaving it rather early (in March). It has a slow, erratic flight that is characteristic and can be used to help identify the species. Rather remarkable for a mammal of such small size, this bat is known to live to 12 years. By comparison, most small rodents and shrews live only about 18 months or less.

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account
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Distribution

Range Description

The range extends from New England, southeastern Ontario, and southwestern Quebec south and west to southeastern Oklahoma, Arkansas, northern Alabama, northern Georgia, and northwestern South Carolina (Menzel et al. 2003). Within this range, the distribution is very spotty, and the bulk of the occurrences and largest populations are in New York, Pennsylvania, West Virginia, and western Virginia. Hall's (1981) map should be taken as potential range; there are no records of this species ever occurring in some parts of the indicated distribution (e.g., Illinois; Jim Herkert pers. comm.). This species is apparently extirpated in Connecticut and Ohio (where known from only one specimen). Elevational range extends to at least 700-800 meters in several states and to at least 1,125 meters in Kentucky (Best and Jennings 1997).
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Eastern small-footed bats are native to the United States and Canada. Despite their wide distribution, they are one of the rarest bats in North America. They range from as far north as Ontario, to as far south as Georgia, and as far west as Oklahoma. This species has been documented in the Ozark Mountains in Arkansas, Missouri and Oklahoma. They are found in the Appalachian mountains north to southeastern Canada and the New England states. In the southern parts of its range, eastern small-footed bats are limited to caves and rocky outcrops in Virginia, North Carolina, South Carolina, Tennessee, Kentucky, Alabama, and northern Georgia.

Biogeographic Regions: nearctic (Native )

  • 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.
  • Linzey, D. 1998. The Mammals of Virginia. Blacksburg, Virginia: McDonald and Woodward Publishing Company.
  • 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.
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range extends from New England, southeastern Ontario, and southwestern Quebec south and west to southeastern Oklahoma, Arkansas, northern Alabama, northern Georgia, and northwestern South Carolina (Menzel et al. 2003). A map is included in Best and Jennings (1997). Within this range, the distribution is very spotty, and the bulk of the occurrences and largest populations are in New York, Pennsylvania, West Virginia, and western Virginia (Amelon and Burhans 2006). Hall's (1981) map should be taken as potential range; there are no records of this species ever occurring in some parts of the indicated distribution (e.g., Illinois; Jim Herkert, pers. comm.). This species is apparently extirpated in Connecticut and Ohio (where known from only one specimen). Elevational range extends to at least 700-800 meters in several states and to at least 1,125 meters in Kentucky (see Best and Jennings 1997).

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Physical Description

Morphology

Eastern small-footed bats are the smallest of the Myotis genus ranging from 3.5 to 6 grams with a length of 75 to 85 mm and a wing span of 210 to 250 mm. They derive their common name from the fact that they are the only member of the Myotis genus (in Virginia) with feet measuring less than 9 mm. The sexes are similar in coloration and size. Their fur is black at the root with brown shiny tips; this gives them their glossy yellowish-brown appearance. Their underside is a dull grayish-brown. The completely black face mask is its most unique feature. They also have black ears, wings, and interfemoral membranes (a stretch of membrane that extends between the legs to the tail). Females have two mammae (or milk glands). They have a strongly keeled calcar (a protruding piece of cartilage on the hind leg to support the intefemoral membrance) and a pointed tragus (a fleshy projection which extends from the base of the ear) of about 9 mm in length.  Their skulls are relatively flat, short, and fragile. Their dental formula is: incisors 2/3, canines 1/1, premolars 3/3, and molars 3/3. Their foreheads slope gradually away from the rostrum lacking the typical prominent forehead of most Myotis species. Their ears are erect and broad at the base and their noses are blunt. Their tails extend beyond the interfemoral membrane.

Eastern small-footed bats are often confused with two other members of the bat family: little brown myotis (Myotis lucifugus) and tri-colored bats (Perimyotis subflavus). Little brown myotis are larger in size and have no mask or keel on the calcar. Tri-colored bats have a blunt tragus, no keel, and a pink coloring on their forearm.

Range mass: 3.5 to 6 g.

Range length: 75 to 85 mm.

Range wingspan: 210 to 250 mm.

Sexual Dimorphism: sexes alike

Other Physical Features: endothermic ; bilateral symmetry

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Size

Length: 8 cm

Weight: 9 grams

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Size in North America

Length:
Range: 73-82 mm

Weight:
Range: 3-7 g
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Diagnostic Description

This bat differs from other sympatric bats by a) small size, < 8.5 cm, b) small hind foot, < 8 mm, c) black face, d) long-keeled calcar, and e) absence of a dark shoulder patch. It differs from M. lucifugus by having golden-tinted, almost yellowish fur and a shorter forearm. It differs from Pipistrellus subflavus by its lighter color, especially the light pinkish forearms, and lack of a keeled sternum (Godin 1977). The skull is much flatter than that of M. lucifugus, and the braincase is narrower; a sagittal crest may be present (Banfield 1974, Godin 1977, Schwartz and Schwartz 1981, Merritt 1987). See Whitaker and Hamilton (1998) for a key to the vespertilionid bats of eastern North America.

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Type Information

Type for Myotis leibii
Catalog Number: USNM 150275
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Male; Adult
Preparation: Skin; Skull
Collector(s): A. Fisher
Year Collected: 1907
Locality: Plummers Island, in Potomac River, 10 mi above Washington, Montgomery County, Maryland, United States, North America
  • Type: Nelson, E. W. 1913 Aug 08. Proceedings of the Biological Society of Washington. 26: 183.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is most often detected during hibernation. In recent years, it has been counted at approximately 125 hibernacula. Recent surveys have greatly increased the number of localities above those known historically; the number of hibernacula may be significantly larger than currently known. Intensive cave and mine surveys have been undertaken in most states where the species occurs, but some sites probably remain unsearched in most states.

The total count for all hibernacula is approximately 3,000 individuals, with roughly 60% of the total number from just two sites in New York. Some of the occurrences probably have not been surveyed completely, and some individuals are undoubtedly missed within some sites because they are hibernating in portions of mines or caves that cannot be reached or easily observed.

This bat always has been considered to be relatively rare (Barbour and Davis 1969). Numbers are reduced in a few sites where older counts are available, and a few historical sites are apparently no longer occupied, but whether these observation reflect declines or changes in distribution is unknown. In Vermont, Myotis leibii has been consistently found in very small numbers and often not detected at all during periodic surveys of various hibernacula dating back to 1934 (Trombulak et al. 2001).

Habitat is mostly hilly or mountainous areas, in or near deciduous or evergreen forest, sometimes in mostly open farmland. In Pennsylvania, Mohr (1976) found this species mostly in heavy hemlock forests in the foothills of mountains that rise to 2,000 feet (600 meters). Unpublished data from the Kentucky Heritage Program indicate that summer roosts include caves, coal mines, buildings, and bridges over rivers (in expansion joints). Warm-season roosts include buildings, towers, hollow trees, spaces beneath the loose bark of trees, cliff crevices, and bridges. Tuttle (1964) reported two individuals found in April in Tennessee under a large flat rock at the edge of a quarry surrounded by woods and cow pastures. In Ontario, about 12 of these bats were found in July behind the door of a shed that was kept open (i.e., positioned against the wall) (Hitchcock 1955). They have been seen resting in limestone caves in West Virginia in spring and summer (Krutzsch 1966).

By far most records come from observations of bats hibernating in winter in caves and mine tunnels. Hibernation occurs in solution and fissure caves and mine tunnels (including coal, iron, copper, and talc mines). Situations near the entrance where the air is relatively cold and dry seem to be preferred (Barbour and Davis 1969), though sometimes deeper locations are used (Schwartz and Schwartz 1981). Roost sites often are deep in crevices, or under rocks on the cave floor, where the bats can be very difficult to find (Davis 1955, Krutzsch 1966, Martin et al. 1966). These bats are usually found singly or occasionally in small clusters, but many may be packed in a crevice; often they hang among other species (Marin et al. 1966). In tight places the body may be horizontal, even belly down. On cave walls, the forearms are somewhat extended rather than parallel to the body axis. Dunn and Hall (1989) noted that 52% of Pennsylvania hibernacula were small caves of less than 150 m (500 feet) in length. Like many other bat species, this one typically forages over ponds and streams.

Systems
  • Terrestrial
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Eastern small-footed bats roost during the spring and summer in buildings, bridges, caves, mines, in hollow trees, tunnels, rock crevices, beneath rocks, and in rocky outcrops. They prefer colder and drier hibernacula than other Myotis species, often seeking the coldest locations within a cave to roost and hibernate. They prefer short caves - often less than 150 m in length - and return to the same spot annually. Across combined observed accounts, 125 caves and mines throughout its range host eastern small-footed bats during hibernation. 90% of their habitat is on private land which is vulnerable to alteration. Only 3.8% of U.S. Forest service upland hardwood, bottomland hardwood, and pine-hardwood forests can support them. Required elevation differs by geographic location. In the 1997 Mammalian Species account by Best and Jennings, the elevation in Virginia is reported at 750 m but ranges from 300-750 m in Pennsylvania.

Range elevation: 300 to 750 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: caves

  • Johnson, J., E. Gates. 2008. Spring migration and roost selection of female Myotis leibii in Maryland. Northeastern Naturalist, 15/3: 453-460.
  • 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.
  • Veilleux, J. 2007. A noteworthy hibernation record of Myotis leibii (eastern small-footed bat) in Massachusetts. Northeastern Naturalist, 14/3: 501-502.
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Habitat Type: Terrestrial

Comments: Habitat is mostly hilly or mountainous areas, in or near deciduous or evergreen forest, sometimes in mostly open farmland. In Pennsylvania, Mohr (1932) found this species mostly in thick hemlock forests in the foothills of mountains that rise to 2,000 feet (600 meters). Warm-season roosts include buildings, bridges (e.g., in expansion joints), towers, hollow trees, spaces beneath the loose bark of trees, cliff crevices, caves, and mines. Tuttle (1964) reported two individuals found in April in Tennessee under a large flat rock at the edge of a quarry surrounded by woods and cow pastures. In Ontario, about 12 of these bats were found in July behind the door of a shed that was kept open (i.e., positioned against the wall) (Hitchcock 1955). They have been seen resting in limestone caves in West Virginia in spring and summer (Krutzsch 1966).

By far most records come from observations of bats hibernating in winter in caves and mine tunnels. Hibernation occurs in solution and fissure caves and mine tunnels (including coal, iron, copper, and talc mines). Situations near the entrance where the air is relatively cold and dry seem to be preferred (Barbour and Davis 1969), though sometimes deeper locations are used (Schwartz and Schwartz 1981). Roost sites often are deep in crevices, or under rocks on the cave floor, where the bats can be very difficult to find (Davis 1955, Krutzsch 1966, Martin et al. 1966). These bats are usually found singly or occasionally in small clusters, but many may be packed in a crevice; often they hang among other species (Marin et al. 1966). In tight places the body may be horizontal, even belly down. On cave walls, the forearms are somewhat extended rather than parallel to the body axis.

Dunn and Hall (1989) noted that 52% of Pennsylvania hibernacula were small caves of less than 150 m (500 feet) in length.

Like many other bat species, this one typically forages over ponds and streams.

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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Long-distance migrations have not been documented. In Ontario, two were recovered in summer 16 and 19 km from the winter hibernation cave (Hitchcock 1955). Barbour and Davis (1969) reported: "In the Mammoth Cave region of Kentucky, M. leibii is fairly common in late summer in the flocks of migrating bats. The whereabouts of these individuals at other seasons in unknown."

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Trophic Strategy

Eastern small-footed bats are insectivores, specializing in nocturnal flying insects while staying 1 to 3 meters off the ground. Prey include beetles, mosquito, moths, and flies. Occasionally they feed on ants as well. One study of fecal samples during fall swarming found 7 orders, 1 superfamily, and 9 families of insects. The insects were very diverse but moths were consumed most abundantly. When foraging, they fly slowly and often feed over water where nocturnal insects are abundant and sometimes fill their stomach within an hour of the start of their foraging bout. They have also been observed feeding in dense forested areas using a gleaning strategy, which is described as eating insects from plants, rocks, or other surfaces. This type of feeding is considered the most efficient for bats with long-wing loading. Eastern small-footed bats have short, broad wings with rounded wingtips to that improve maneuverability in dense vegetation.

Animal Foods: insects

Primary Diet: carnivore (Insectivore )

  • 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.
  • United States Department of Agriculture. Notes on Foraging Activity of Female Myotis leibii in Maryland. NRS-8. Delaware, OH: U.S. Forest Service. 2009.
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Comments: Probably the diet is almost exclusively flying insects; specific data are lacking. Feeding flights are relatively slow and fluttery and occur over ponds and streams and along roads.

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Associations

Eastern small footed bats host the following ectoparasites: mites (Androlaelaps casalis and Cryptonyssus desultorius), chiggers (Leptotrombidium myotis), and ticks (Ornithodorus kelleyi). Females in maternity colonies have an increased probability of exposure to ectoparasites. Females in northern regions of the United States are more likely to carry the Trypanosoma infection originating from the bat bug, Cimex brevis. These bat bugs are common in maternity colonies in Ontario.

Commensal/Parasitic Species:

  • mites (Androlaelaps casalis)
  • mites (Cryptonyssus desultorius)
  • chiggers (Leptotrombidium myotis)
  • ticks (Ornithodorus kelleyi)
  • white-nose syndrome fungus (Geomyces destructans)
  • bat bug (Cimex brevis )
  • Trypanosoma

  • 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.
  • 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.
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During the summer months, eastern small footed bats are found in cracks and crevices which reduce the chance of predation. Little is known about their specific predators, but bats are often eaten by hawks and owls, snakes, raccoons, and weasels.

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 300

Comments: This species may be represented by a large number of occurrences (subpopulations). It is most often detected during hibernation. In recent years (but prior to the prevalence of white-nose symdrome), it was counted at approximately 125 hibernacula (Amelon and Burhans 2006). These recent surveys greatly increased the number of localities above those known historically; the number of hibernacula may be significantly larger than currently known. Intensive cave and mine surveys have been undertaken in most states where the species occurs, but some sites probably remain unsearched in most states. However, as a result of die-offs associated with white-nose syndrome, some sites may no longer harbor this species.

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Global Abundance

250 - 10,000 individuals

Comments: Population size is not completely known. Prior to the recognition of white-nose symdrome, one total count for all known hibernacula was approximately 3,000 individuals, with roughly 60 percent of the total number from just two sites in New York. Some of the occurrences probably have not been surveyed completely, and some individuals are undoubtedly missed within some sites because they are hibernating in portions of mines or caves that cannot be reached or easily observed.

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General Ecology

Mites (identification pending) have been found on the ears of an individual in South Carolina (Mary Strayer, pers. comm.). Related species are parasitized by trematodes, cestodes, chiggers, mites, fleas, and bat bugs (Cimex sp.).

This is one of the many mammals known to carry rabies (Constantine 1979).

Possible predators include domestic cats, mink, raccoons, opossum, fish, frogs, snakes, and birds of prey. Most of these are known to prey occasionally on other Myotis species (Barbour and Davis 1969).

Bats are often important components of cave ecosystems, providing the primary energy input in the food chain in the form of guano (Horst 1972, Poulson 1972).

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Life History and Behavior

Behavior

Eastern small-footed bats use echolocation to locate prey, typical among insectivores. Search-phase call is first used to locate an insect. While in pursuit, an approach-phase call is emitted. Immediately before consuming prey, they emit a terminal-phase call or feeding buzz. Both the approach-phase (pre-buzz call) and the terminal-phase (buzz call) are used to determine a range on the prey and maintain the location of the prey item. In one study the duration of search-phase calls were 2.8 ms and other studies have recorded calls as long as 5 ms. The minimum frequency is 46.1 KHz and the maximum frequency is 84.5 KHz.

Communication Channels: acoustic

Perception Channels: visual ; tactile ; acoustic ; echolocation ; chemical

  • Murray, K., E. Britzke, L. Robbins. 2001. Variation in search-phase call of bats. Journal of Mammalogy, 82/3: 728-737.
  • 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.
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Cyclicity

Comments: These bats emerge from daytime retreats shortly after sunset, while there is still some light. In the northeastern United States, they seldom enter hibernation caves before mid-November; depart by March, or possibly earlier in Vermont (Godin 1977).

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Life Expectancy

Eastern small-footed bats are estimated to live 6 to 12 years in the wild. This is affected by predation, habitat availability, and exposure to parasites or fungi. The maximum recorded lifespan in captivity was 12 years. In northern regions of their geographic range, males have a higher rate of survival (75%) than females (42%). This could be due to the higher demand on females during reproduction. Maternity colonies are not always present, so there is a large increase in energy output for thermoregulation of both pregnant and lactating females compared to those involved in clustering behaviors.

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.

Range lifespan

Status: captivity:
12 (high) years.

Typical lifespan

Status: wild:
6 to 12 years.

Average lifespan

Status: captivity:
12 years.

  • 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.
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Lifespan, longevity, and ageing

Maximum longevity: 12 years (wild)
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Reproduction

Swarming, which is important for mate selection, breeding, and hibernacula selection, occurs from late summer through early fall. Eastern small-footed bats are polygynandrous, so both males and females have many mates.

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.

Mating System: polygynandrous (promiscuous)

Maternity colonies have been observed in New Hampshire, Kentucky, North Carolina, South Carolina, and Ontario. These colonies ranged from a 12 to 33 individuals and the roost locations were diverse. Thirteen individuals were found in rock crevices, 20 in guardrail crevices on a concrete bridge, 12 behind a shed door, and others in wood piles and picnic shelters. Little is known about their breeding behavior. However, one study found a maternity colony in an abandoned cabin in North Carolina. This colony consisted of 33 individuals: 22 adult females, 1 non-reproductive adult male, 3 juvenile males, and 7 juvenile females. Female eastern small-footed bats typically have one offspring per year between May and July. Sperm is stored throughout hibernation, where the female is in sub-estrus, from mid-November to March. Mating has also been documented during the winter if a male and a female are aroused from hibernation at the same time. This is when the female releases an egg and delayed fertilization occurs.

During reproduction, males initiate copulation and the female's role is passive. Both sexes are quiet throughout copulation. The male mounts the female and tilts her head back to a 90 degree angle by biting down on the hairs at the base of the skull. The male uses his thumbs to further stabilize his position on the female as he moves his projecting penis below her interfemoral membrane. The interfemoral membrane does not hinder posterior copulation due to the free movement of the penis. After the male has entered the female the penis appears to move rapidly and independently of any movements by the hindquarters.

Newborn eastern small-footed bats weigh 20 to 35% of their mother's weight. This large size is thought to limit the number of offspring to one because another fetus would overexert the mother while foraging. There is a 1:1 sex ratio at birth. When raising young, females choose the site with the highest solar exposure to decrease energy expenditure. Warmer sites provide thermal stability for young when the female goes out on foraging trips.

Breeding interval: Once per year

Breeding season: Fall swarm

Range number of offspring: 1 to 1.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; sperm-storing ; delayed fertilization

Average number of offspring: 1.

Only females care for newborns. They go on foraging trips for food, feed, protect, and teach the young. Mothers leave the newborn soon after birth to look for food. Weaning time is not known.

Parental Investment: female parental care ; pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

  • 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.
  • Johnson, J., J. Gates. 2007. Food habits of Myotis leibii during fall swarming in West Virginia. Northeastern Naturalist, 14/3: 317-322.
  • 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.
  • 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.
  • 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.
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The basic major life cycle stages minimally include breeding (e.g., rearing of young) and hibernation.

Mating behavior is similar to that of the little brown bat (Wimsatt 1945) and so, probably, are other facets of reproduction (Banfield 1974). Breeding may occur in the fall, with the sperm stored in the uterus over winter. Active gestation lasts probably two months, with a single offspring born annually, probably in early July (Merritt 1987).

Survival rates are significantly lower for females (42%) than for males (76%) (van Zyll de Jong 1985). One individual is reported to have lived 12 years (Hitchcock 1965).

One summer colony included about 12 individuals (Hitchcock 1955). Colonies are usually small (< 15), though a few number in the hundreds.

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Arroyo-Cabrales, J. & lvarez-Castaeda, S.T.

Reviewer/s
Medelln, R. & Schipper, J.

Contributor/s

Justification
This species is listed as Least Concern in view of its wide distribution, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.

History
  • 1996
    Lower Risk/least concern (LR/lc)
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In 2009, eastern small-footed bats were were placed on many conservation lists. In Alabama, Arkansas, Massachusetts, Maryland, Maine, New Hampshire, New Jersey, Oklahoma, Pennsylvania, West Virginia, Virginia, and Vermont they are listed as "critically imperiled". In Georgia, Kentucky, North Carolina, and New York, they is listed as "imperiled". In Connecticut, Massachusetts, Maryland, Missouri, North Carolina, New Jersey, New York, Ohio, Oklahoma, Tennessee, Virginia, West Virginia, and Georgia they are listed as a "species of special concern." In Pennsylvania and Vermont they are listed as "threatened," and are endangered statewide in New Hampshire. On a federal level, they are listed as a species of special concern and is 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 with a stable population trend. They are threatened by human activities because of their reliance on forests for foraging. Activties such as logging, wind turbines, agricultural and urban development contribute to foraging habitat destruction. Oil, gas, and mineral development can destroy roosting sites and contaminents can leak into local streams.

Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

  • 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/.
  • 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.
  • Terwilliger, K. 1991. Virginia's Endangered Species. Blacksburg, Virginia: The McDonald and Woodward Publishing Company.
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N2 - Imperiled

United States

Rounded National Status Rank: N2 - Imperiled

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NatureServe Conservation Status

Rounded Global Status Rank: G2 - Imperiled

Reasons: Fairly widespread in southeastern Canada and eastern United States; very spotty distribution; rarely found in large numbers; few high quality occurrences exist; historically the total numbers counted have been very low in comparison to the total number of caves and mines surveyed; severe declines associated with a fungal pathogen (white-nose syndrome) have occurred in much of the range since 2006; severity of the decline is not precisely known but may be quite high..

Intrinsic Vulnerability: Highly to moderately vulnerable.

Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.

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Population

Population
Approximately 80% of the known occurrences are of poor estimated viability; just 7% are believed to have good or excellent viability. In most instances, surveys yield very few individuals of this species in any particular location.

Most occurrences have been counted only within the past decade or two and are not revisited regularly, making the assessment of population trend difficult. Many biologists believe that this species is basically stable, having declined little in recent times, but that it is vulnerable, especially in its cave hibernacula. The population at one site in Arkansas has increased in recent years, probably due to reduced winter disturbance following the installation of a cave gate.

Population Trend
Stable
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Global Short Term Trend: Decline of 70 to >90%

Comments: Until recently, most occurrences were not revisited regularly, making the assessment of population trend difficult. Also, the relatively sparse populations of this bat make it difficult to determine trends. Through the 1990s, many biologists believed that this species was basically stable but vulnerable, especially in its cave hibernacula. The population at one site in Arkansas increased in recent years, probably due to reduced winter disturbance following the installation of a cave gate.

Trend over the past three generations (probably at least 15 years) is not precisely known but likely a major decline has occurred. Since 2006, white-nose syndrome (WNS) has reduced some hibernating bat populations in northeastern North America by 80-97 percent (http://www.fort.usgs.gov/wns/). In Massachusetts, New York, and Vermont, Myotis leibii populations have declined 78 percent overall since the advent of WNS (Langwig et al. 2009). In New York, some hibernating populations of M. leibii have disappeared, though the bats were not common in pre-WNS surveys (Hicks et al., 2008, unpublished data). The geographic extent of WNS continues to expand, and it is reasonable to assume that WNS will continue to decimate M. leibii popuations.

Global Long Term Trend: Unknown

Comments: This bat always has been considered to be relatively rare (Barbour and Davis 1969). Through the 1990s, numbers were reduced in a few sites where older counts are available, and a few historical sites were apparently no longer occupied (e.g., see Hall 1979, but compare Dunn and Hall 1989), but whether these observations reflected declines or changes in distribution is unknown. In Vermont, Myotis leibii was consistently found in very small numbers and often not detected at all during periodic surveys of various hibernacula dating back to 1934 (Trombulak et al. 2001). Numbers detected in Pennsylvania declined between the 1930s (7 sites, 363 individuals) and late 1970s (none detected) (Felbaum et al. 1995).

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Threats

Major Threats
Some mines may be threatened by closure or collapse. Ceiling collapse may kill bats outright or, more significantly, alter cave microhabitat enough to make it unsuitable. A few cave occurrences are threatened or have been reduced in quality due to commercialization for tourism.

Threats to summer sites are unknown, but are likely to be moderate due to alteration of riparian habitats. Conversion of forested habitats to agricultural and residential uses has decreased the amount of preferred habitat in some areas, but the bats do make use of bridges and various other non-natural roost sites.

Improper gating of caves to protect bats may result in site abandonment. For example, the large colony of M. leibii at Fourth Chute Cave, Quebec, was driven out by blocking the flow of cold air (Mohr 1976). In contrast, gating of cave entrances in other locations (e.g., Aitkin Cave, Pennsylvania) has led to increases in M. leibii populations. With its small numbers and spotty distribution, isolated colonies of M. leibii are particularly vulnerable to extirpation by chance events, especially when concentrated during winter months. On the other hand, in contrast to certain other bats that assemble in vast numbers in relatively few sites, the population of M. leibii as a whole is not vulnerable to localized events.

This bat tends to hibernate near cave entrances; hence it may be vulnerable to freezing in abnormally severe winters. THREATS TO BATS IN GENERAL: Perhaps the most serious threat to cave-dwelling bats is human disturbance during hibernation. Very low levels of noise, light, and heat from lanterns are sufficient to awaken hibernating bats, which then expend energy moving about and deplete critical reserves of body fat. When disturbance is repeated, bats (especially juveniles) are likely to perish. "By the end of the winter energy reserves may be insufficient to meet the demands of the first feeding forays, when emerging insects may be scattered and scarce, or the bats may be too weak to make long flights to their summer territories" (Mohr 1976). Such disturbance is equally lethal, whether caused by vandals, well-meaning spelunkers, or bat researchers. Intentional killing of bats in caves by clubbing, stoning, burning, bombing, etc. has been a significant cause of mortality. Documented examples are numerous (e.g. Tuttle 1979). Bats are sometimes exterminated from commercial caves, or if not, leave or move to suboptimal habitats due to increased disturbance. Poisoning by pesticides, heavy metals, and other environmental contaminants has been and may remain a significant threat. Destruction of roost and foraging habitat by reservoir inundation, strip mining (especially limestone), deforestation, drainage of wetlands, development, etc., and pollution or siltation of waterways with consequent decline in insect production are additional potential adverse impacts (Tuttle 1979). Hundreds of thousands of bats have been destroyed by natural flooding of caves.
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Degree of Threat: High

Comments: The most serious threat is white-nose syndrome (WNS), an often (but not always) lethal condition caused by a fungal pathogen (Geomyces destructans). WNS was first noticed in 2006 in New York. Since its initial discovery, WNS has spread rapidly and now has been been documented throughout the range of Myotis leibii (http://www.fws.gov/whitenosesyndrome/maps/WNSMap_060111_300dpi_DS.jpg). WNS affects Myotis leibii and several other bat species and resulted in more than a million bat deaths in the northeastern United States in just 5 years. Myotis leibii population declines (100 percent) were observed during surveys at Hailes Cave, New York, from 2005 to 2008, and these declines may be attributed to WNS (Hicks et al. 2008). As of mid-2012, WNS was still spreading but was confined almost exclusively to areas east of the Mississippi River (plus a few locations in Missouri and Oklahoma).

Closures of mines used for hibernation are a potential threat, but there is no evidence that mine closures are currently affecting Myotis leibii populations (USFWS 2011). Some mines may be threatened by collapse. Ceiling collapse may kill bats outright or, more significantly, alter cave microhabitat enough to make it unsuitable. A few cave occurrences are threatened or have been reduced in quality due to commercialization for tourism.

Threats to summer sites are unknown but likely to be moderate due to alteration of riparian habitats. Conversion of forested habitats to agricultural and residential uses has decreased the amount of preferred habitat in some areas, but the bats do make use of bridges and various other non-natural roost sites. Reliance on loose shale, talus, or karst formations often found in oil-, gas-, and mineral-rich lands makes M. leibii vulnerable to habitat loss associated with natural resource exploitation (Center for Biological Diversity 2010, USFWS 2011).

Development of wind power poses a threat in some areas. Myotis leibii typically roosts in talus areas that occur on ridgetops. In the Appalachian Mountains, such roosting areas coincide with past, present, and anticipated future wind power development,. Thus this bat may be exposed to both habitat loss due to project construction and direct mortality from turbine operation, though mortality from turbines has not yet been documented (Center for Biological Diversity 2010, USFWS 2011).

Improper gating of caves to protect bats may result in site abandonment. For example, the large colony of M. leibii at Fourth Chute Cave, Quebec, was driven out by blocking the flow of cold air (Mohr 1972). In contrast, gating of cave entrances in other locations (e.g., Aitkin Cave, Pennsylvania) has led to increases in M. leibii populations.

With its small numbers and spotty distribution, isolated colonies of M. leibii are particularly vulnerable to extirpation by chance events, especially when concentrated during winter months. On the other hand, in contrast to certain other bats that assemble in vast numbers in relatively few sites, the population of M. leibii as a whole is not vulnerable to localized events.

This bat tends to hibernate near cave entrances; hence it may be vulnerable to freezing in abnormally severe winters.

THREATS TO BATS IN GENERAL: Other than white-nose syndrome, perhaps the most serious threat to cave-dwelling bats is human disturbance during hibernation. Very low levels of noise, light, and heat from lanterns are sufficient to awaken hibernating bats, which then expend energy moving about and deplete critical reserves of body fat. When disturbance is repeated, bats (especially juveniles) are likely to perish. "By the end of the winter energy reserves may be insufficient to meet the demands of the first feeding forays, when emerging insects may be scattered and scarce, or the bats may be too weak to make long flights to their summer territories" (Mohr 1976). Such disturbance is equally lethal, whether caused by vandals, well-meaning spelunkers, or bat researchers.

Intentional killing of bats in caves by clubbing, stoning, burning, bombing, etc,. has been a significant cause of mortality. Documented examples are numerous (Greenhall 1973, Harvey 1976, Tuttle 1979, and others). Bats are sometimes exterminated from commercial caves, or if not, leave or move to suboptimal habitats due to increased disturbance.

Poisoning by pesticides, heavy metals, and other environmental contaminants has been and may remain a significant threat (Clark 1988). Destruction of roost and foraging habitat by reservoir inundation, strip mining (especially limestone), deforestation, drainage of wetlands, development, etc., and pollution or siltation of waterways with consequent decline in insect production are additional potential adverse impacts (Tuttle 1979). Hundreds of thousands of bats have been destroyed by natural flooding of caves (Hall 1962, Brady 1979).

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Management

Conservation Actions

Conservation Actions
There is a strong conservation easement held by The Nature Conservancy (TNC) on the second largest occurrence. TNC has a management agreement giving limited protection to the largest occurrence and one occurrence with apparently good viability is on National Park Service land in Arkansas. Several occurrences with fair to poor estimated viability in various states are either owned by TNC or are on Federal land.

Summer surveys throughout the species known range should be a high priority for inventory work. Winter hibernacula surveys should continue with emphasis on searching sites which have not been surveyed, improving counts in sites which have not been completely or thoroughly surveyed, and monitoring some portion of the known sites on a regular basis (perhaps every other year as recommended for Myotis sodalis sites) to establish baseline population trend data.
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Restoration Potential: Restoration to formerly occupied caves may be possible if conditions of temperature, air flow, moisture, and access remain unchanged, but there is little guiding information. Mohr (1976) thought this an unlikely option: "Attempts to transfer bat populations from houses to tunnels in Pennsylvania (Mohr 1942) were totally unsuccessful and recent evidence of the extreme loyalty--philopatry--of bats to their accustomed caves (Tuttle 1975) leaves little hope for reestablishing deserted hibernating sites." There is evidence of Indiana bats (Myotis sodalis) and big-eared bats (Corynorhinus spp.) returning to abandoned caves after gating or fencing (Craig Stihler, pers. comm.) In the case of gray bats (Myotis grisescens), Tuttle (1979) thought they might return to previously used caves, but that "any cave not already used by gray bats, however, should be assumed to be unsuitable for future use. Such caves probably do not provide essential temperature or roosting conditions, are too distant from acceptable foraging or hibernating sites, or are too vulnerable to predation or flooding." He thought that all suitable caves were probably occupied long before the arrival of man. Myotis leibii (among others) has found new habitat in certain mine tunnels, but little is known about the specific microhabitat conditions required.

Preserve Selection and Design Considerations: Preserves should include sufficient buffer area above and around the hibernaculum cave to protect it from disturbances that might alter water and air flow, temperature, and humidity. Adjacent to summer roosts and maternity sites (in the unlikely event that they are known), sufficient foraging area (probably along a stream) should be protected from deforestation, contamination with pesticides, and other major impacts. Too little is known about this species' ecology to make more specific recommendations.

Management Requirements: With the present scarcity of pertinent information, management can focus only on protection of hibernation caves summer roosts. The locations of caves, especially in remote areas, should not be publicized, and trails to entrances should be eliminated. Depending on the situation and potential for irresponsible traffic or vandalism, it may be useful to construct a fence or steel gate and/or place warning/interpretive signs. Hibernacula should be closed from November through March.

Public education as to the true nature and value of bats could avoid many problems and is urgently needed. Staff of national and state forests and parks, wildlife agencies, agricultural extension agents, and others in similar positions should be educated first so they can enlighten the public.

Foraging areas should be identified and protected from pesticides and other contaminants that may poison bats directly as well as destroy their food sources. Analysis of guano may be a convenient way of checking colonies for contamination (Clark 1988), in the rare cases of where summer colonies are known and there is sufficient accumulation. Bats for diagnostic study are generally frozen immediately. Consult a U.S. Fish and Wildlife Service Environmental Contaminant Field Specialist in cases of suspected poisoning or disease.

Logging above and around bat caves should be limited; deforestation can alter cave temperature, humidity, and air and water flow. Blasting in limestone mines or winter logging in the immediate vicinity of caves could cause arousal of hibernating bats. Some forest cover around the cave entrance and foraging area may offer significant protection from predators and periods of exceptionally cold spring weather (Tuttle 1979). Some Myotis species seem to require wooded corridors from roosts to feeding areas (Craig Stihler, pers. comm.).

Harvey (1981) offered cave protection suggestions: "Where gates are necessary, they should be used with extreme care to avoid detrimental effects to bats and cave microclimates. Each gate must be designed specifically for the cave to be protected, considering number of bats, type of colony, air flow, and entrance size and configuration. They should not be used at summer caves unless adequate free flight space can be provided above. Gates should be vertical (not horizontal or slanting) and should not be placed in entrances smaller than 1.8 m (6 ft) in diameter. Care must be taken so that gates do not restrict normal air flow. They should be constructed of welded steel bars 1.9 cm (3/4 inch) to 2.5 cm (1 inch) in diameter and of sufficient hardness to be invulnerable to bolt cutters. Free ends of bars should be grouted into solid rock. If a concrete footing is necessary, it should not extend above original ground level. Access openings should be constructed with durable hinges, hasps, and locks. Openings through which bats are expected to fly should be 15.2 cm (6 inches) vertically and 61 cm (24 inches) horizontally. In situations where vandalism is likely, a weak-link design may be employed. The lock, hasp, or some other easily replaceable part should be relatively weak so that vandals, if determined, can break in without doing excessive damage to the gate." [Modern gates constructed with 4-inch (10-cm) angle iron may make this unnecessary; also, latest designs minimize the number of vertical members, which seem to disturb bats (Craig Stihler, pers. comm.).]

"At some caves, especially those with sinkhole entrances, a simple vertical gate is impractical. In these situations a 'cage' or 'box' type gate may be necessary so that bats can fly up into the 'box' and then out through vertical openings. If gates are used at summer caves, they should be 'half-gates.' Such a gate is practical only in large cave entrances, where it can extend part way to the ceiling and still allow adequate space (at least 1 m, ideally more) above the gate through which bats can fly" (Harvey 1981). ["Half-gates" are probably only necessary for caves used also by gray bats (Craig Stihler, pers. comm.).] After gates are placed at cave entrances, bat activity should be monitored to assure that gates are not having detrimental effects on bat populations. Gates should be inspected periodically and often so that necessary repairs can be made promptly." (Harvey 1981).

"Fences do not afford as much protection as steel gates and are easier to cut or climb. Nevertheless, circumstances at some caves make fences more practical, especially in situations where gates might result in abandonment of the cave by bats. Chainlink, barbed-wire-topped fences with posts set in concrete are recommended. Barbed-wire should not extend into flight space required by bats" (Harvey 1981). [The bottoms of fences must also be secured; people going underneath are a problem (Craig Stihler, pers. comm.).]

"At caves which are infrequently visited, or which can be easily observed by the landowner, a sign alone may be adequate to prevent disturbance. In some circumstances, a sign might attract unnecessary attention to a cave, in which case the management agency might place a sign inside the cave, or not use a sign." (Harvey 1981).

"Signs should be of durable construction and fixed solidly in place to minimize vandalism, and should be placed so as to not interfere with bat flight patterns or air flow. They should be located where potential violators will see them, and should be placed behind the gate or fence if such a structure has been erected. Wording may vary from cave to cave, but signs should contain both a warning and interpretive message. At many caves it may be permissible to permit entry during times of the year when bats are not present. A sign containing that message, plus information on how to obtain a key to gated or fenced caves, might discourage vandals and encourage the cooperation of spelunkers. Where a cave is located in a public use area, the management agency may wish to use a more elaborate sign with a more detailed interpretive message" (Harvey 1981).

White and Seginak (1987) also discussed gate designs for bat caves.

Management Research Needs: Very little is known about the ecology, reproduction, and life history of this species. Especially needed is knowledge of critical habitat requirements, including hibernacula, summer roost and maternity sites, and foraging areas, food sources and impacts on them, and reproductive biology. Movements between hibernacula and summer sites need to be investigated.

The potential for translocation of colonies threatened by habitat destruction needs study (Mohr 1976).

There is still a need for new monitoring methods that are accurate and minimize impact on the bats.

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Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: There is a strong conservation easement held by The Nature Conservancy (TNC) on the second largest occurrence. TNC has a management agreement giving limited protection to the largest occurrence and one occurrence with apparently good viability is on National Park Service land in Arkansas. Several occurrences with fair to poor estimated viability in various states are either owned by TNC or are on Federal land. However, these forms of protection do not shield the bats from population decimation caused by disease.

Needs: All high-quality occurrences should be fully protected along with as many other viable occurrences as possible. Protection should include the ground surface above and adjacent to caves and mines and may need to include mineral rights for some mines. Protection, whether by ownership, easement, or management agreement, must include some means of limiting winter disturbance.

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Relevance to Humans and Ecosystems

Benefits

Bats are noted carriers of rabies, which results in a nearly 100% fatality rate if not detected on time. Five out of 45 species of bats has been recorded transmitting rabies to humans in the United States, one of which is suspected to be the eastern small-footed bat. Eastern small-footed bats might also carry Histoplasmosis, a disease caused by the fungus Histoplasma capsulatum. This presents itself with flu-like symptoms and disappears with antifungals and sometimes without need for any treatment. Eastern small-footed bats might also be considered a nuisance because they roost in human structures.

Negative Impacts: injures humans (carries human disease)

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Eastern small footed bats prey on beetles and mosquitoes which are pests to humans and agriculture.

Positive Impacts: controls pest population

  • 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.
  • 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.
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Risks

Stewardship Overview: The eastern small-footed myotis is most vulnerable during hibernation. The caves and mines that serve as significant hibernacula should be protected from disturbance from November through March. If necessary, the entrance should be gated. Foraging areas (mostly streams and ponds) should be protected from pesticides and anything else that might adversely affect production of the bat's insect food. Forest should not be eliminated above or around hibernacula, nor around foraging areas. Public education about the value of bats is necessary in the long-term.

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Wikipedia

Eastern small-footed myotis

The eastern small-footed bat (Myotis leibii) is a species of vesper bat. It can be found in Ontario, Quebec in Canada and in the Eastern United States.[1] It is among the smallest bats in eastern North America[2] and is known for its small feet and black face-mask. Until recently all North American small-footed Myotis were considered to be "Myotis leibii". The western population is now considered to be a separate species, Myotis ciliolabrum. The Eastern small footed bat is extremely rare throughout all of its range, and due to white-nose syndrome their numbers are continuing to dwindle. Most occurrences of this species have only been counted within the past decade or two and are not revisited regularly making the assessment of their population very difficult to assess. Many biologists believe the species is stable, having declined little in recent times, but that it is vulnerable, especially in its cave hibernacula.

Description[edit]

The Eastern small footed bat is between 65 to 95 millimeters in length, has a wingspan of 210 to 250 millimeters, and weighs between 4 to 8 grams.[3] The bat got its name from its abnormally small hind feet, which are only 7 to 8 millimeters long.[4] The fur on the dorsal side of their body is dark at the roots, and fades to a light brown at the tips, which gives the bats a signature shiny, yellow-brown appearance. The fur on the dorsal side of the body is a dull gray color, which is believed to help camouflage themselves in their hibernacula.[5] The defining characteristic of this bat is its face-mask, which is completely black.[4] They also have black ears, wings and interfemoral membrane, (the membrane between the legs and tail).[5] Like all bats, the Eastern small footed Bat has a patagium that connects the body to the forelimbs and tail, allowing the animal to fly. Their head is very flat and short, with a forehead that slops gradually away from the rostrum, a feature that is unique to other individuals in the Myotis species.[4] They have erect ears, which are very broad at the base and a short flat nose. They have a keeled calcar (protruding cartridge on the hind legs to support the interfemoral membrane) as well as a pointed tragus[disambiguation needed] Their tail is between 25-45 millimeters in length and protrudes past their interfemoral membrane, and they have a dental formula of 2/3, 1/1, 3/3, 3/3.[4]

Range and distribution[edit]

The range of this species includes Northern Arkansas and southern Missouri, East to the Appalachian Mountains and Ohio River Basin, North into New England, southern Ontario and Quebec.[6] Distribution of the bats is spotty within their entire range, and they are considered to be very uncommon. These bats prefer to reside in deciduous or coniferous forests. They are active in mountain ranges from 240–1125 meters in height. During the summer and spring they prefer to roost in rock bluffs, buildings, and turnpike tunnels as well as rocky cliffs, talus slopes and shale fields; where they roost under rocks and in crevices during the day. The largest populations of Myotis leibii have been found in New York, Pennsylvana, West Virginia and Western Virginia. (red list) The total count of individuals in all hibernacula in which they have been found is 3,000, with roughly 60% of the total number from just two sites in New York.[7] Unfortunately, 90% of their habitat is on private land which makes it difficult to protect them.[7]

Diet[edit]

The eastern small-footed Myotis is believed to feed primarily on flying insects such as beetles, mosquitoes, moths, and flies, (Barbour and Davis 1969; Harvey et al. 1999; Linzey 1998; Merritt 1987) and are capable of filling their stomachs within an hour of eating.[8] They are nighttime foragers and usually forage in and along wooded areas at and below canopy height, over streams and ponds, and along cliffs. Moths compose nearly half of their diet, and they forage primarily on soft-bodied prey [9] It is believed that the avoidance of hard prey is due to their small, delicate skulls. The Food habits of M. leibii are similar to those of the closely related California (M. californicus) and western small-footed bats (M. ciliolabrum), as well as other North American Myotis (e.g., little brown bat, (M. lucifugus), and northern bat, (M. septentrionalis).[10]

Hibernation[edit]

The Eastern small- footed bat is most often detected during hibernation, and has been counted at approximately 125 hibernacula.[11] They are one of the last species to enter hibernation in the fall and the first to leave in the spring, with a hibernation period lasting from late November to early April. They have been found in very cold caves and mines and can tolerate lower temperatures than other bat species. (Whitaker and Hamilton 1998) Unlike most other bat species they prefer to hibernate in caves and mines that are very short in length (150m) and are most often found hibernating near the entrance of their hibernacula where temperatures sometimes dip below zero, and the humidity is very low. (Barbour and Davis 1969; Merritt 1987; Harvey 1992). This location choice puts them at a greater risk of white nose syndrome and it is estimated that the disease alone has caused a 12% decrease in their population since 2006.[12] These bats also tend to hibernate individually, or in groups of less than 50, and have also been found hibernating with other species of bats, which makes them very difficult to find.[8]

Spring and summer roosting[edit]

Very little is know about the summer roosting locations of this species, as well as where maternal colonies are formed, which makes a proper species distribution estimate very difficult to obtain. The first study into the summer roosting habits was only done in 2011 so information is scarce. This study performed by Johnson, Kiser and Peterson discovered that these bats most commonly use ground level rock roosts in talus slopes, rock fields and vertical cliff faces for their summer roosts.[13] On average they change their roosts every 1.1 days, males travel about 41 meters between consecutive roosts and females around 67 meters. They also found that females roosting sites were closer to ephemeral water sources than male’s roosts. Females who have young require roost sites that receive a lot of sunlight in order to keep the pups warm while the mother is away from the nesting site.[14] These preferred summer roosting habitats are very difficult to find, and are becoming even sparser due to mining, quarrying, oil and gas drilling and other mineral extraction, as well as logging, sprawl highway construction, wind energy and other forms of agricultural, industrial and residential development.[12]

Mating and reproduction[edit]

One of the reasons this bat is in so much danger is its slow reproduction rate. The Eastern small-footed bat can only have one offspring a year, although a few instances of twins have been noted. Mating most often occurs in autumn and the female stores the male’s sperm throughout hibernation in the winter. Fertilization occurs in the spring once the females are active again, and gestation occurs between 50–60 days with young being born in late May and early June. Mating has also been noted to occur throughout the hibernation period if individuals awake. During the time of breeding large number of bats come together in a behavior commonly known as “swarming.” All bats of this species are polyandrous, meaning they mate with multiple partners throughout the mating period. This mating behavior allows them to increase the likelihood of copulation, and therefore increase their reproductive success.

Males initiate copulation by mounting the female and tilting her hear back 90 degrees. The male then secures his position by biting and pulling back on the hairs at the base of the female’s skull. The male then uses his thumbs to further stabilize his position and enters the female under her interfemoral membrane. Both individuals have been noted to be very quiet during the copulation process. Once the process is over the male dismounts the female and flies away to find another mate.

When born the newborn bat, which is called a “pup” is completely dependent on its mother. They weigh between 20-35% of their mothers body weight. Newborn bats are called pups, and are dependent on their mothers.[6] They weigh between 20-35% of their mothers body weight. The young’s large body size is believed to lead to high-energy expenditure from the mother, which is what limits her to only having one offspring a year.[14]

Threats[edit]

The main threat to this species is habitat disturbance, both natural and human caused. They are also under great threat of white nosed syndrome, pollution (especially waster pollution) and human disturbance during hibernation. Very low levels of light, noise and heat are sufficient enough to wake hibernating bats. Once awoke the bats begin to expend energy and deplete critical fat reserves. If these disturbances are repeated bats, especially juveniles become very susceptible to death. White nosed syndrome is a fungal infection that attacks bats while they hibernate. 7 million bats of 6 different species are estimated to have been killed since 2006. There has been a 12 percent decline in eastern small-footed bats from white nosed syndrome alone. Due to their dependency on rare ecological features where they nest they are at particularly high risk from mining, quarrying, oil and gas drilling and other mineral extraction, as well as logging, highway construction, wind energy and other forms of agricultural industrial and residential development.

Conservation[edit]

Although the Eastern small-footed bat is listed as a species of least concern on the IUCN red list, many states in which the bat resides have begun listing it has a threatened species and have begun conservation efforts in order to improve its numbers. This species is not protected by federal law, but was a former C2 candidate for listing prior to the abolishment of that category by the U.S. fish and wildlife service in 1996.[15] Some states (e.g. Pennsylvania) have given the species legal protection while others have recognized its apparently low numbers and consider the eastern small-footed Myotis a species of concern. In the report “Species of Special Concern in Pennsylvania” by Genoways and Brenner (1985),[15] the Pennsylvania Biological Survey assigned Myotis leibii the status of “threatened.” Other states, such as Virginia, are currently working to get the Eastern small-footed Myotis legal protection. Despite these efforts not many conservation projects have been put in place to help the species. Due to their strange hibernation patterns, and the lack of information regarding their spring and summer roosting locations proper conservation efforts are very difficult. The bats will not usually use bat boxes like many other bat species, due to their tendency to nest alone or in very small groups, so this is not an appropriate action to assist in habitat disturbance issues with this species.

Longevity[edit]

The eastern small-footed bat has been recorded living up to the age of 12 years.[3]

See also[edit]

References[edit]

  1. ^ a b Arroyo-Cabrales, J. & Ticul Alvarez Castaneda, S. (2008). Myotis leibii. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 17 January 2009.
  2. ^ Blasco, J. "Myotis leibii". Animal Diversity Web. Retrieved 2007-06-30. 
  3. ^ a b Linzey, D.; Brecht, C. "Myotis leibii (Audubon and Bachman); Eastern small-footed Bat". Discover Life. Retrieved 2007-12-07. [dead link]
  4. ^ a b c d Best, T., and Jennings, J. (1997) ”U.S. Fish and Wildlife Service Federal register notice of a 90-day finding for Eastern small-footed bat and Northern Long-eared bat”, “U.S. Fish and Wildlife Service” 547: 1-6
  5. ^ a b Chapman, B. (2007) ”The Land Manager's Guide to Mammals of the South. Durham, NC,” “The Nature Conservancy”, 191:1-559.
  6. ^ a b Best, T., J. Jennings. (1997) “Myotis leibii”, “Mammalian Species”, 547:1-6.
  7. ^ a b Erdle Y., S. Hobson. (2001) “Current status and conservation strategy for the eastern small footed Myotis (Myotis leibii)”,”Virginia Department of Conservation and Recreation”, National Heritage Technical Report: #00-19.
  8. ^ a b Best, T., J.S. Altenback., J.M. Harvey. “Eastern small-footed bat,” “The Tennessee Bat Working Group”
  9. ^ Freeman, P. W. (1981). “Correspondence of food habits and morphology in insectivorous bats”, “Journal of Mammalogy,” 62:166-173.
  10. ^ Whitaker, J. O., C. Masser., S. P. Cross. (1981). “Food habits if Eastern Oregon bats, based on stomach and scat analyses,” “Northwest Science,” 55:281-292.
  11. ^ Arryo-Cabrales, J., T.A. Castaneda (2008) “Myothis Leibii in IUCN red list,” “IUCN Red List of Threatened Species”. 13.1.
  12. ^ a b Salazar, K., M, Matteson (2010) “Petition to list the Eastern small-footed bat 'Myotis leibii' and Northern Long eastern bat Myotis septentrionais as threatened of endangered under the Endangered Species Act,” The Bester for Biological Diversity.
  13. ^ Johnson, J.S., J,D, Kiser., K.S. Wareous., T.S. Peterson (2011) “Day-Roost of Myotis leibii in the Appalachian Ridge and valley of Western Virginia”, “Northern Naturalist”, 18(1):96-106.
  14. ^ a b Johnson, J., E. Gates (2008). “Spring migration and roost selection of female Myotis leibii in Maryland,” “Northeastern Naturalist,” 15/3:453-460.
  15. ^ a b Heoways. H., F.J. Brenner (1985). “Species of Special Concern in Pennsylvania,” “Carnegie Museum of Natural History.”
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Names and Taxonomy

Taxonomy

Comments: Formerly, M. ciliolabrum was included as a subspecies of M. leibii (or M. subulatus). Based chiefly on cranial measurements, Van Zyll de Jong (1984) recognized western populations of what had been known as M. subulatus as a species (M. ciliolabrum) distinct from eastern populations, for which the appropriate name is M. leibii. Electrophoretic data support the conclusion that the two taxa are specifically distinct (Herd 1987). Wilson and Ruff (1999) and Baker et al. (2003) regarded M. ciliolabrum and M. leibii as separate species. Koopman (in Wilson and Reeder 1993) did not recognize M. ciliolabrum as a species distinct from M. leibii, but Simmons (in Wilson and Reeder 2005) did. See also Miller and Allen (1928), Glass and Baker (1968), and Hall (1981) for nomenclatural information. Myotis leibii is regarded as monotypic (Best and Jennings 1997).

In a phylogenetic study based on mtDNA data, M. leibii was included within clades containing both M. californicus and M. ciliolabrum (Rodriguez and Ammerman 2004). Further data from M. leibii are necessary to validate its phylogenetic relationship to M. ciliolabrum and M. californicus (Rodriguez and Ammerman 2004). Comparisons among outgroups (M. yumanensis, M. lucifugus, and M. evotis) found sufficient support for specific status of M. leibii, but sequence divergence between M. evotis and the leibii group was small (2.9%) and within the intraspecific range. Further sampling of M. evotis is necessary to establish the level of divergence between M. evotis, as well as other long-eared Myotis, and the leibii group (Rodriguez and Ammerman 2004).

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