occupies three types of roosts: day, night, and hibernation roosts. Locations of roosts are chosen based upon the presence of stable ambient temperatures. Day and night roosts are used by active bats and include, but are not limited to, buildings, trees, under rocks, and in piles of wood. Day roosts have very little or no light, provide good shelter, and typically have southwestern exposures to provide heat for arousal from daily torpor.
Night roosts are selected for their confined spaces where large concentrations of bats can cluster together to increase the temperature in the roost. These roosts are primarily occupied when temperatures are below 15°C. Night roosts are usually away from day roosts; this may diminish the accumulation of feces at day roosts and avoid signaling predators. Day and night roosts are inhabited during spring, summer, and fall months, whereas during the winter, hibernacula sites are used.
Nursery roosts are similar to day roosts but are warmer than ambient temperature. They are usually occupied only by females and their offspring. Females use the same nursery colony every year.
Hibernaculum sites may be shared with Myotis yumanensis. These sites usually include abandoned mines or caves where the temperature is continuously above freezing and humidity is high. Northern populations of bats enter hibernation in early September and end in mid-May; southern populations enter in November and end their hibernation in mid-March. does not make tremendously long migrations during the change of seasons. (Wilson and Ruff, 1999; Fenton and Barclay, 1980; Koopman and Gudmundsson, 1966; Nowak, 1994; Wilson and Ruff, 1999)
The fur ofis glossy, and varies in color from dark brown, golden brown, reddish, to olive brown. Albino individuals have also been observed. The ventral side has lighter pelage. The wing and interfemoral membranes are nearly hairless and dark brown or black. The tragus is blunt and of medium height. Their ears usually do not extend past the nose when laid forward. has small ears and large hind feet. The fore and hind limbs have five metapodials. The hind foot has hairs that extend past the toes.
The skull has some distinguishing characteristics.lacks a saggital crest, has a shortened rostrum, 38 teeth, and a upslope profile of the forehead. In addition, the braincase is flattened and subcircular when observed dorsally.
Mating occurs between adult females and adult males; subadult males are not sexually mature until after their first year. Mating occurs in two phases: active and passive. During the active phase, both partners are awake and alert. In the passive phase, active males mate with torpid individuals of both sexes; passive phase mating is approximately 35% homosexual. Mating is random and promiscuous. Females in active phase usually mate with more than one male. In both active and passive phase matings, males mate with multiple females. (Fenton and Barclay, 1980; Wai-Ping and Fenton, 1988)
Swarming at the hibernacula occurs during late summer and fall; activity decreases with lower temperatures. Swarming serves a prenuptial function, along with showing the young suitable hibernation roosts. During late July, bats arriving at the hibernacula are adult males and nonparous females; females and subadults appear in early August. Swarming (Fenton and Barclay, 1980; Schowalter, 1980)may travel large distances, causing mixing of populations from different areas. During the swarming period, little brown bats are receptive to calls of conspecifics.
Normally, bats hang head down; females giving birth reverse their position, so their head is up. Young are born into the interfemoral membrane; only one young is born per year. The pups’ eyes and ears open within hours of birth, and deciduous teeth are fully erupted. Pups must cling to the female’s nipple using their deciduous incisors, large thumbs, and hind feet. The young start hearing at day 2 and develop auditory sensitivity similar to that of an adult by day 13. On approximately day 9.5, pups are able to thermoregulate and in three weeks they are able to fly.
Independence from the mother comes when the pups start to fly and become self-supporting at about 4 weeks of age. Adult weight is attained at about 4 weeks of age as well. Spermatogenesis starts in May and ends in August. (Fenton and Barclay, 1980)
Mothers nurse their own young and distinguish from other pups by odor and calls. For 18 to 21 days, pups ingest only milk from their mother. Weaning takes place at about three weeks; at this time, the permanent teeth fully erupt and pups start to feed on insects along with the mother's milk. After weaning, the pups have a drop in body weight as they learn to catch insects. It is not clear if mothers bring insects to their young or help to teach them to hunt. However, many female/young pairs are captured together, suggesting that there is some period of supervised learning before independence. Males play no role in parental care. (Fenton and Barclay, 1980)
Little brown bats are primarily nocturnal and emerge from their roosts at dusk. Primary activity occurs about two or three hours after dusk and secondary activity may occur before dawn; most individuals return to the roost by four or five o’clock in the morning. These bats usually enter daily torpor. During the winter, hibernation time depends on altitude and location of the roosts. It usually starts between September and November and ends in March to May. The young remain active longer in the fall to build fat deposits to last the winter. (Barbour and Davis, 1969; Cockrum, 1956; Nowak, 1994)does not migrate long distances for hibernation roosts. Individuals travel only up to 100 miles. This species does not show territoriality at roosts, and large colonies of as many as 300,000 bats have been reported in a single roost.
During hibernation, little brown bats undergo repeated periods of torpor lasting 12 to 19 days, but may remain torpid for as long as 83 days. Signals for the end of hibernation include weather conditions of the area and arousal of neighboring bats. (Fenton and Barclay, 1980; Tuttle, 1991)
Little brown bats vary their body temperatures greatly. These bats can be cooled to 6.5 degrees Celsius and heated to temperatures of 54 degrees Celsius without harm.deposits 13 distinct type of brown fat, allowing individuals to efficiently and rapidly produce heat during arousal from hibernation torpor.
Myotis lucifugus occultus can increase urine concentration in order to better withstand water stress in low humidity environments with limited water supply. Only this subspecies is known to do this, however; most subspecies of have a poor ability to regulate urine concentration. In general, usually lives within close proximity to water. (Fenton and Barclay, 1980; Tuttle, 1991)
Little brown bats travel several kilometers between day roosts and feeding sites. (Nowak, 1994)
Little brown bats feed largely on aquatic insects. Midges are the primary source of food of , but a large part of their diet comes from other aquatic insects. When available, beetles are easily identified by echolocation and easily captured. Other insects consumed include caddisflies, moths, mayflies, lacewings, and occasionally mosquitoes. (Anthony and Kunz, 1977; Fenton and Barclay, 1980)
Domestic cats have become adept at catching bats due to the close proximities of roosts to human habitations. Many predators take advantage of the high concentrations of bats in roosts. Predators such as martens and fishers take advantage of weak young that fall or hibernating individuals that are dislodged by grooming activities. Other predators of include mice, owls, weasels, hawks, snakes, raccoons, domestic cats, and other small carnivores. (Fenton and Barclay, 1980; Griffin, 1958)
Little brown bats have a major impact on the insect populations around their roosts. Active bats eat half of their body weight per night and lactating females eat more than their body weight per night. One (Barbour and Davis, 1969; Fenton and Barclay, 1980; Wilson and Ruff, 1999)consumes approximately 3 to 7 grams of insects each night.
Members of this species are heavily researched and provide scientists with a bat model to test and study many aspects of the order, including echolocation, social behavior, feeding, and habitat use. Additionally, little brown bats eat pests that transmit diseases and eat agricultural products. They are also predators of mosquitoes and other pest around human habitats. (Barbour and Davis, 1969; Wilson and Ruff, 1999)
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%. (Cryan, 2010; National Park Service, Wildlife Health Center, 2010)
There are six subspecies of M. l. alascensis, M. l. carissima, M. l. lucifugus, M. l. occultus, M. l. pernox, and M. l. relictus. Several of these subspecies were previously considered separate species: M. l. occultus, M. l. pernox, and M. l. carissima. (Fenton and Barclay, 1980; Hall, 1981):
Tanya Dewey (editor), Animal Diversity Web.
Nancy Shefferly (editor), Animal Diversity Web.
Aaron Havens (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat