Vespertilionid bats I

(Vespertilioninae)

Class Mammalia

Order Chiroptera

Suborder Microchiroptera

Family Vespertilionidae

Thumbnail description
Small- to medium-sized bats with well-developed tails that in most species are completely covered by tail membranes

Size
Range about 1.4–5.5 in (3.5–14 cm) in body length, and about 0.09–1.59 oz (2.5–45 g) in weight

Number of genera, species
30 genera; about 267 species

Habitat
Forests and open fields, both moist and dry regions, lowlands and mountains up to the tree line

Conservation status
Extinct: 2 species; Critically Endangered: 6 species; Endangered: 17 species; Vulnerable: 46 species; Lower Risk: 59 species

Distribution
Old and New World from the tropics into temperate zones

Evolution and systematics

The subfamily of vespertilionines is by far the largest of the five subfamilies within the family Vespertilionidae. With 30 genera and about 267 species, it makes up more than 90% of all the species within Vespertilionidae, which itself is the largest bat family.

In the subfamily Vespertilioninae, the major genera include:

• Myotis, 84 species
• Pipistrellus, 50 species
• Eptesicus, 32 species
• Chalinolobus, 15 species
• Scotophilus, 10 species

Eighteen of the remaining genera each have fewer than five species, and half have only one representative species. The two-species genus Antrozous, or the pallid bats, is notable in that some systematists place it in its own family, Antrozoidae, or in its own subfamily, Antrozoinae, within the vespertilionids.

Phylogenetic studies indicate that the family Vespertilionidae is likely most closely related to the families Mystacinidae, or the New Zealand short-tailed bats, and Molossidae, or the free-tailed and mastiff bats.

Physical characteristics

Vespertilionines are wide-ranging. The bamboo bat (Tylonycteris pachypus) and African banana bat (Pipistrellus nanus) are not only the smallest in the subfamily at about 0.1 oz (3g) in weight, but also two of the tiniest bats in the world. At the opposite end of the spectrum is the subfamily's largest member: the large mouse-eared bat (Myotis myotis) with its nearly 14-in (35-cm) wingspan.

Although a large number of vespertilionines are brown, a few are frosted with silver, yellow, or reddish tips. The hoary bat (Lasiurus cinereus), for example, has a luxuriant pelage highlighted in white. Fur in other species within this subfamily may be golden like that of the yellow bat (Rhogeessa anaeus) of Belize, ginger and white like that of Welwitch's hairy bat (M. welwitschii) of Africa, or vivid orange like that of Myotis formosus of Southeast Asia.

Vespertilionines have some features in common. All lack the fleshy nose ornaments common to so many other bat families. In fact, the family Vespertilionidae is often called "the plain-faced bats." Most of the vespertilionines also have small eyes, although a few, such as the pallid bat (Antrozous pallidus), have noticeably larger eyes. Ear size can be small or large, with many species having tiny, rounded ears smaller than their head while others have enormous ears that extend almost the length of their bodies. The long-eared bat

(Plecotus auritus) has extraordinarily long ears, but it can tuck them so far under the wing (done during the daily sleep and in hibernation) that only the pointed ear cover (tragus) can be seen.

Other distinctive features of vespertilionines—indeed all species within the family Vespertilionidae—are a well developed tragus that reaches up from the base of the ear, and a nearly naked patagium, or flight membrane, that covers the relatively long tail. Vespertilionine tails are commonly half as long as the body.

Distribution

Vespertilionines spread almost around the globe. The pipistrelles (Pipistrellus) include more than three dozen species in North America, Europe, Africa, Madagascar, Asia, and Australia. The noctule bats (Nyctalus) are distributed from the Azores through Europe and Asia to the Philippines, and the big brown bats (genus Eptesicus) are distributed nearly worldwide. The northern bat (E. nilssoni) has an extraordinary resistance to cold; its distribution extends into the Arctic. The mouse-eared bats (Myotis spp.) are especially noted for their wide distribution, and members of this genus are found almost everywhere bats exist.

Habitat

Given their nearly global distribution, it is not surprising that the habitat preferences of the vespertilionines vary greatly. While a large number of the temperate members inhabit caves during winter, their summer haunts can range from caves to woodlands, and riparian areas to deserts. A few vespertilionines stay away from disturbed areas, but many, like the serotine bat (Eptesicus serotinus), will make use of cracks and crevices in human-made structures for roosts. Many species utilize tree hollows and loose bark for daytime roosts in the summer, with various southern species even taking advantage of these spots for hibernation. A few more tropical species make use of vegetation for their roosts. The African banana bat (Pipistrellus nanus), for example, invariably spends the day in young banana leaves that are still rolled up.

Behavior

Temperate vespertilionines hibernate—sometimes alone, sometimes in the hundreds. Commonly, individuals awaken periodically during the winter. If the outside temperature is warm enough, they will travel outside of the hibernaculum,

which may be a cave, attic, or tunnel, and look for food. Following hibernation, male bats in this subfamily will typically spend the summer alone, while females will group together in maternity colonies to bear and raise their young. A maternity colony of pipistrelles (Pipistrellus pipistrellus), for example, may include more than 100 females. Unlike most vespertilionines, pipistrelle nursing colonies may include some males. After the young are independent, the bats abandon these sites.

Mouse-eared bats generally return to the same summer and winter roosts, which may be as much as 125 mi (200 km) away from each other. Another change of roosts is occasionally made in summer or in winter. Roost changes are also typical of other vespertilionine species.

Most species begin mating in the fall, but very little is known about courtship behaviors. The little brown bat (Myotis lucifugus), which is one of the most well-known bats in the New World, engages in no courtship. Mating simply involves the male grasping the female by the nape of her neck during copulation, performed upside down. The two separate after copulation, often to find additional partners.

In the fall, many temperate vespertilionines disappear from northern habitats, assumedly to migrate south, although some species' seasonal movements are little known. The hoary bat is one species whose migration pattern is generally understood, although specifics are still lacking. These bats begin migrating in late summer to early fall, with often-large, mixed-sex groups traveling to the Gulf states and Mexico to spend the winter. However, the destination of some individual populations is still in question. For instance, populations of the red bat (Lasiurus borealis) of North America that spend their summers in the upper Great Lakes may not fly as far south as more

southern populations, perhaps migrating only as far as the Ohio River valley for the colder months instead of the Gulf states or Mexico. Part of the mystery surrounding many bat migratory movements stems from their hibernacula, which are often hidden, remote, and undiscovered. Return migrations for many species, including the hoary bat, begin when gravid females head north. The males follow shortly thereafter.

Vocalizations are used for communication and carry a variety of information. Acoustic studies on hoary bats show that they use mainly multiharmonic signals with considerable intra- and inter-individual variability in five signal variables (call duration, call interval, highest, lowest frequency, and frequency with maximum energy) to recognize each other and communicate with one another. Echolocation behavior is influenced by the presence of conspecifics. When bats hunt together, call duration decreases and call interval increases. While hunting, the pallid bat flies slowly, and close to the ground, with rhythmic dips and rises. Instead of echolocating, the desert-adapted pallid bat relies on sounds made by its prey to locate and capture a meal, often crickets or scorpions.

Some species (pallid bats) are known to produce a musky skunk-like odor from glands on the muzzle. There have been no experimental studies to determine the function of this odor—it may be a defense mechanism for repelling predators.

Feeding ecology and diet

The bats in this group are almost exclusively insectivorous. Armed with echolocation capability, these skilled flyers are typically able to catch moths, beetles, flying ants, and other insects on the wing, but many will also glean leafhoppers, spiders, or other arthropods off of foliage. A few have expanded their diet to include fish or other vertebrates. Remains of food under feeding sites of the pallid bat (Antrozous pallidus) have included bugs, crickets, and locusts, and occasionally scorpions, lizards, and geckos. The Mexican fishing bat (Pizonyx visesi) employs its long hindfoot claws to spear fish. Daubenton's bat (Myotis daubentonii) also occasionally eats fish.

Vespertilionines commonly rest during the day in roosts, and forage at night. Some species, like the western barbastelle (Barbastella barbastellus) become active early in the evening and hunt for a few hours. Noctules leave their sleeping site early, and may begin the hunting flight in the afternoon, particularly in the fall. The spotted bat (Euderma maculatum) is active through the night. All typically rest between foraging flights to aid digestion.

Predation on these bats is generally rare. Predators may include owls who catch and kill a bat while it is foraging for insects, or mammals, like raccoons or skunks, and snakes that may find a daytime roost.

Reproductive biology

This subfamily of bats generally begins mating in the fall. Females store sperm in the reproductive tract after mating and during hibernation and then ovulate in the spring. In some species,

such as the big brown bat (Eptesicus fuscus), mating also occurs in the spring. Gestation averages about two months, with altricial young typically born in late spring or early summer. Litter size is commonly one or two pups, although some species produce more. During birth, most females turn right side up and catch the infant in the tail membrane. Hoary bats and red bats have four teats, and occasionally raise four pups. On average, females lactate for one to two months. During the same period, the young learn to fly from their mothers just three weeks after birth on average and begin to forage on their own. The young may become independent during the first year, or spend the winter with the family unit. They are often left in roosts with hundreds of other bats. Females of many species become sexually mature the first year, while males typically mature the following year. Compared to mammals of a similar size, bats can live a very long time. They average 10 years or so but records of bats living 15 years and longer under natural conditions are not uncommon and there is one record of a little brown bat surviving for at least 32 years in the wild.

Conservation status

Many vespertilionines are experiencing population declines, particularly due to habitat destruction. A large number of these bats roost in dying or dead trees, as well as abandoned buildings, which are often targeted for removal.

Legislative, organizational and grassroots efforts are now under way to protect populations. The Indiana bat (Myotis sodalis), for example, is listed as Endangered by the IUCN. The U. S. Fish and Wildlife Service lists the causes of the decline as habitat disturbance, destruction and degradation, and pesticide use. Also listed as endangered under the U. S. Endangered Species Act, the species is protected from hunting or harassment. In addition, ongoing programs are managing bat habitats to ensure that species have sufficient roosting and hibernation sites, and to help educate the public on the bat's plight.

Concerned individuals have also become involved in the decline of vespertilionines and other species, and made various artificial roosts, like bat houses, more popular. According to Paul A. Racey of the U. K.'s Bat Conservation Trust, "Instead of trying to get rid of bats in their attics or other spaces, many home owners frequently ask bat workers how they can attract bats to their house. To accommodate bats, special roofing tiles and clay bricks that facilitate the entry of bats to roof spaces are now marketed in the U. K."

Significance to humans

Bats have major cultural importance, especially in Asia. But perhaps the greatest significance of bats to humans stems from their insectivorous diet. A single vespertilionine can eat thousands of insects a night, and many of these arthropods are seen as pest species. For instance, bats help control populations of mosquitoes, flies, moths, beetles, and other insects. While decreases in fly or mosquito populations are readily seen as a benefit for all humans, unchecked populations of beetles, moths, and other pest species can cause significant damage to agricultural crops and forests.

In addition, many vespertilionine bats are very susceptible to pesticides and other chemicals, making them good bioindicators. These bats carry rabies and other zoonotic diseases of concern to humans.

Species accounts

List of Species

Pallid bat

Antrozous pallidus

subfamily

Vespertilioninae

taxonomy

Antrozous pallidus (La Conte, 1856), El Paso County, Texas, United States. Six subspecies.

other common names

French: Chauve-souris blonde; Spanish: Murcielago pálido.

physical characteristics

Body length ranges from 3.6–5.5 in (9.2–14 cm), wingspan about 14 in (35.5 cm), and forearm length from about 1.8–2.4 in (4.5–6 cm). Adults weigh from 0.46 to 1.02 oz (13–29 g). A large-eared, yellowish bat with big eyes compared to other vespertilionids. The dental formula is (I1/2 C1/1 P1/2 M3/3) × 2 = 28.

distribution

North America from central Mexico through the western to west-central continental United States and into extreme southwest Canada. Also in western Cuba.

habitat

Found in deserts, and other drier regions, they roost in small openings in cliffs, trees, and buildings.

behavior

In addition to the normal echolocation calls used in hunting, pallid bats also have intraspecies communication calls. These

"directive" calls bring mothers and their young together, and also facilitate the gathering of adults in a population to a new roost. Pallid bats roost in caves, rock crevices, mines, hollow trees, and buildings and they have been reported to hibernate in some areas.

feeding ecology and diet

An insectivorous bat that can live in an arid habitat in part by obtaining necessary water from its insect prey and employing water-conservation behaviors, such as folding its wings. Besides insects, they also eat scorpions and centipedes, as well as flower nectar and pollen.

reproductive biology

Promiscuous. Mating starts in late October. Following delayed fertilization, gestation lasts about 60 days, and litters are born in late spring to early summer. Litter size is typically one or two altricial young per female. The young begin to fly at about one to one-and-a-half months. Young females attain sexual maturity during the first year, and males a year later.

conservation status

Not threatened.

significance to humans

Aid cross-fertilization of plants.

Western barbastelle

Barbastella barbastellus

subfamily

Vespertilioninae

taxonomy

Barbastella barbastellus (Schreber, 1774), Burgundy, France. Two subspecies.

other common names

French: Barbastelle d'Europe, barbastelle commune; German: Mopsfledermaus; Spanish: Murcielago de bosque.

physical characteristics

Body length ranges 1.8–2.4 in (4.5–6.0 cm), wingspan 9.4–11.8 in (24–30 cm), and forearm length about 1.2–1.8 in (3.1–4.5 cm). Adults weigh from 0.2 to 0.42 oz (6–12 g). A small-to medium-sized bat with black, notched ears that are about as big as its head and are connected at the base across the fore-head. The head and back are covered with light-tipped blackish fur. Ventral fur is a bit lighter in color. The dental formula is (I2/3 C1/1 P2/2 M3/3) × 2 = 34.

distribution

Found in scattered pockets throughout much of central and northern Europe.

habitat

Forests often near water, roosting in trees or human buildings, and hibernating in tree hollows and caves.

behavior

This bat is quite rare and its behavior is little known. Scattered reports, however, indicate that the western barbastelle hibernates from fall to spring, but frequently awakens to fly outside of its hibernaculum. During the summer, they roost alone or in small maternity colonies typically under bark, in slight hollows in trees, or in tree stumps, but they will also crawl into tight crevices in buildings. From one to about six individuals usually share a given roost, but during the breeding season barbastelles apparently congregate in fairly large numbers. Individuals are also known to migrate up to 60 mi (100 km).

feeding ecology and diet

Diet is mainly moths and other flying insects taken while on the wing, but also includes insects and other small arthropods plucked off plants. It appears to become active earlier than most vespertilionids, sometimes emerging from its roost before sunset.

reproductive biology

Little known, but reported to mate in autumn, with one young born in early summer, and weaning occurring about a month-and-a-half later. Thought to be promiscuous.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

Helps to control insect populations.

Big brown bat

Eptesicus fuscus

subfamily

Vespertilioninae

taxonomy

Eptesicus fuscus (Beauvois, 1796), Philadelphia, Pennsylvania, United States. Ten subspecies.

other common names

French: Chauve-souris brune; German: Große braune Fledermaus; Spanish: Murcielago ali-oscuro.

physical characteristics

Body length ranges 3.5–5.3 in (9–13.5 cm), and forearm length about 1.6–2.2 in (4–5.5 cm). Adults weigh from 0.39 to 0.88 oz (11–25 g), with the heavier weights typical just before hibernation and the lighter weights immediately afterward. The dental formula of the big brown bat is (I2/3 C1/1 P1/2 M3/3) × 2 = 32. A small- to medium-sized bat with brown to reddish brown or tan dorsal pelage, a lighter-colored underside, and brownish black wings.

distribution

Throughout the continental United States, southern Canada, most of Mexico, the Caribbean, much of Central America, and northwest South America.

habitat

Big brown bats spend much of their summer in the hollows of trees, and small hiding places beneath tree bark or leaves. They are also common in attics, barns, and in other human-built structures. They are typically found near water and/or woods or meadows, but also are quite common in desert habitats. During the winter, they usually hibernate in caves.

behavior

Females will form maternity colonies, with three dozen or more females roosting together in an attic, tree hollow or other location. In the fall, big brown bats move to caves, where they soon enter hibernation. A hibernaculum may include only a handful of bats.

Their courtship and mating behaviors are unknown, although genetic differences between litter mates show that they may have different fathers.

feeding ecology and diet

Their diet includes scarab beetles, as well other flying and ground-dwelling insects. Big brown bats typically hunt on the wing, picking moths and other flying insects out of the air or snatching grasshoppers and beetles from the floor of an open forest. Each night, a big brown bat can eat several thousand insects, often equal to its body weight.

reproductive biology

Mating commonly occurs in early spring, although some mate the previous fall or winter. Early mating females delay fertilization until the spring. Gestation lasts 50 to 60 days, and the young are born in late spring or early summer. Litter size is typically one or two altricial young per female. The young are weaned and begin to fly at about one to one-and-a-half months. Young females attain sexual maturity at four months, while males mature at four to 16 months. May be polygynous.

conservation status

Not threatened.

significance to humans

Big brown bats consume large quantities of pest insects.

Spotted bat

Euderma maculatum

subfamily

Vespertilioninae

taxonomy

Euderma maculatum (J. A. Allen, 1891), Santa Clara Valley, California, United States.

other common names

French: L'Oreillard maculé; Spanish: Murcielago moteado.

physical characteristics

Adults weigh about 0.53–0.71 oz (15–20 g), and their body length ranges 4.1–5.0 in (10.5–12.6 cm). A distinctive bat with three, large white spots on black dorsal fur. It has huge, pink ears that are about the same length as its 1.8–2.2 in (4.5–5.5 cm) forearms. Its underside is mostly white, and its face is brown and black.

distribution

North America from northwest Mexico, through the western United States and into British Columbia in Canada.

habitat

Ponderosa pine and other forests, typically near water and rocky cliffs.

behavior

Active through the night, spotted bats have echolocation calls that are audible to humans, including buzzes made while feeding. During the daytime, they rest in roosts set in small openings in steep cliffs sides.

feeding ecology and diet

Insectivores, these bats capture moths and other prey insects in fight, sometimes diving within a few feet of the ground after a low-flying arthropod.

reproductive biology

Little is known of the reproductive biology of this species. The young are born in late spring to early summer. Litter size is typically one altricial young per female.

conservation status

Not threatened.

significance to humans

Helps to control insect populations.

Allen's big-eared bat

Idionycteris phyllotis

subfamily

Vespertilioninae

taxonomy

Idionycteris phyllotis (G. M. Allen, 1916), San Luis Potosí, Mexico. Two subspecies.

other common names

English: Mexican big-eared bat, lappet-brown bat; Spanish: Murcielago de grandes orejas de Allen.

physical characteristics

Average adult body length is 2–2.3 in (5–6 cm), weight is 0.28–0.56 oz (8–16 g), and forearm length is 1.7–1.9 in (4.2–4.9 cm). These long-eared bats are distinguished by the presence of lappets, which are fleshy, horizontal flaps lying over the forehead. They have dark-brown to black dorsal fur tipped with tan, reddish or yellowish brown. Like other bigeared bats, they can curl up their ears to lie them quite flat against their bodies. When unfurled, the ears are about twothirds the length of the body.

distribution

Interior southwestern United States and Mexico.

habitat

Mountainous woods, particularly ponderosa and other pines, frequently near waterways, but also occasionally in arid scrubs and grasslands.

behavior

Nocturnal bats that are highly skilled flyers, even capable of flying vertically. During the summer, males likely travel alone, while females will form maternity colonies of up to 150 individuals in tunnels, rock piles, and mine shafts. These bats disappear late in the fall, but little is known about possible migratory patterns or their winter whereabouts.

feeding ecology and diet

Excellent flyers, these bats feed on insects, especially in-flight moths, but also various beetles taken from foliage. While echolocating at constant frequency, they often make loud peeps and clicks that are audible to humans.

reproductive biology

Litter size is generally one, and pups are born in early summer. Little else about their reproductive biology is known.

conservation status

Not threatened.

significance to humans

Helps control agricultural pest insect populations.

Silver-haired bat

Lasionycteris noctivagans

subfamily

Vespertilioninae

taxonomy

Lasionycteris noctivagans (Le Conte, 1831), eastern United States.

other common names

French: Chauve-souris argentée; German: Silberhaar-Fledermaus; Spanish: Murcielago plateado.

physical characteristics

Average adult body length is 3.5–4.7 in (9–12 cm), weight is 0.32–0.39 oz (9–11 g), and forearm length is 1.5–1.8 in (3.7–4.5 cm). Medium-sized brown to black bat with noticeable white fur tips, accounting for its "silver" appearance. The dental formula is (I2/3 C1/1 P2/3 M3/3) × 2 = 36.

distribution

North America from west-central Canada to Nova Scotia, through much of the continental United States except Florida, and into extreme north-central Mexico.

habitat

Found in forests near water.

behavior

Normally solitary bats that will sometimes travel in twos or threes, and will form small groups during migration. Migrations occur in late fall and spring when they travel between their summer home in the northern United States and Canada, and their winter environs in southern areas. Those that migrate to warmer climates typically hibernate beneath loose bark, in crevices in trees or rocky cliffs, in buildings, or in piles of lumber. Those that spend their winters farther north may hibernate in caves. Silver-haired bats are known to form maternity colonies, which they make in small tree crevices.

feeding ecology and diet

This slow-flying, nocturnal bat typically searches for food over open areas, including ponds, and eats flies, moths, mosquitoes, and other mainly small arthropods. Predators include large owls and skunks.

reproductive biology

Their reproductive biology is little known, but mating is believed to occur in autumn, and following delayed fertilization, litters of two naked young are born in early summer.

conservation status

Not threatened.

significance to humans

Assist in controlling pest insect populations.

Hoary bat

Lasiurus cinereus

subfamily

Vespertilioninae

taxonomy

Lasiurus cinereus (Beauvois, 1796), Philadelphia, Pennsylvania, United States. Three subspecies.

other common names

French: Chauve-souris cendrée; German: Weißgraue Fledermaus; Spanish: Murcielago blanquizco.

physical characteristics

Body length ranges 5.1–5.9 in (13–15 cm), weight about 0.88–1.23 oz (25–35 g), and forearm length 1.8–2.2 in (4.6–5.5 cm). Large, dark brown to dark gray bats with white-tipped fur and a wingspan that can reach 12 in (30.5 cm). Unusually, its tail membrane and parts of its wings are lined with fur. The dental formula is (I1/3 C1/1 P2/2 M3/3) × 2 = 32.

distribution

Throughout the continental United States, Mexico, and Central America, north into south-central and southeastern Canada, and as far south as Argentina and Chile in South America. They are also found in Hawaii, where they are the only native land mammal.

habitat

Wide-ranging from deserts to tundra to mountains, but most common in deciduous and coniferous forests.

behavior

Migratory bats that leave their summer haunts in late summer to early fall, and return in the spring. They migrate in large groups of sometimes 200 or more. Except for mother-and-young families, these bats are solitary animals. While other bats seek caves, tree hollows, or other cover during hibernation, hoary bats frequently hibernate in the open, often on the side of a tree. They use their furred tail membrane as a blanket to protect them from the winter weather.

feeding ecology and diet

This nocturnal bat's diet is mainly moths, supplemented by occasional flies, beetles, and other insects. The Hawaiian sub-species prefers termites. An agile and fast flier, it often hunts in open areas. Predation on hoary bats is rare, but raptors and snakes are known to pose risks.

reproductive biology

Assumed to mate in flight in late summer or early fall, with gestation delayed until winter to early spring. The young are born in late spring to early summer. Litter size is typically two altricial young per female, but may be as high as four. The young begin to fly at about one to one-and-a-half months. Young females attain sexual maturity at four months, while males mature at four to 16 months. Mating system is not known.

conservation status

Not threatened.

significance to humans

Assist in controlling pest insect populations.

Little brown bat

Myotis lucifugus

subfamily

Vespertilioninae

taxonomy

Myotis lucifugus (Le Conte, 1831), near Riceboro, Georgia, United States. Six subspecies.

other common names

English: Little brown myotis; French: Petite Chauve-souris brune; German: Kleine braune Fledermaus; Spanish: Murcielago marrón Americano.

physical characteristics

Wingspan varies from 7.9 to 10.6 in (20–27 cm), and forearms about 1.4–1.6 in (3.5–4 cm). With a body length of 3.1–3.7 in (8–9.5 cm), they are smaller than the big brown bat (Eptesicus fuscus), with which they are often confused. Adults weigh 0.21–0.49 oz (6–14 g), tending toward the higher end before entering hibernation and the lower end when awakening in the spring. A small bat that ranges in color from light to dark brown dorsally and light tan to whitish on its belly. They are similar in appearance to the Indiana bat (M. sodalis), but the little brown bat lacks the keel present on the calcar of the Indiana bat. The dental formula of the little brown bat is (I2/2 C1/1 P3/3 M3/3) × 2 = 38.

distribution

Found through much of North America, including southern and south-central Alaska, the southern two thirds of Canada, all but the extreme southeastern, south-central and southwestern United States, and north-central Mexico.

habitat

Little brown bats are found in a wide variety of habitats. They spend much of their summer in the hollows of trees, or in attics, barns, between wooden vents, and in other human-built structures. They are typically found near water and/or woods. During the winter, they hibernate in caves.

behavior

Males are typically solitary during the summer. Females, however, will form maternity colonies with a dozen to more than 1,000 bats roosting together often in hot locations, such as attics, where temperatures can top 100°F (38°C). During the winter, males and females roost together in caves, sometimes migrating more than 150 mi (250 km) between their winter and summer roosts. A single hibernaculum draws bats from a wide area, often totaling 200,000 bats or more.

feeding ecology and diet

These are insectivorous bats that hunt in flight for their favorite prey items—moths, mayflies, and chironomid flies—by either snatching the insect with their jaws or scooping them into their wings and bringing them to their mouths. Adults may eat close to, and sometimes more than, their body weight in insects in a single night. Little brown bats are most active and do the bulk of their feeding early in the evening and at dawn.

Predators may include raptors that catch a bat in flight, or raccoons that reach a roost. However, predation on little brown bats is not prevalent.

reproductive biology

A promiscuous species, mating commonly occurs in late summer and early fall as bats begin to move into the hibernaculum. Fertilization is delayed until the following spring. Gestation lasts 50 to 60 days, and the young are born in late spring to mid-summer. Litter size is typically one altricial young per female. After clinging to the mother for a day or two, the young bat hangs in the roost until it reaches about three to four weeks old, when it begins to fly and is weaned. The young reach full size at about two months old, and attain sexual maturity at one to two years. A long-lived bat, individuals in the wild have reached 33 years of age.

conservation status

Not listed by the IUCN, however, some populations are experiencing declines. Numbers of the subspecies M. l. occultus, for instance, have dropped precipitously, particularly through habitat destruction.

significance to humans

These voracious insectivores help control pest insect populations, and also serve as bio-indicators.

Noctule

Nyctalus noctula

subfamily

Vespertilioninae

taxonomy

Nyctalus noctula (Schreber, 1774), France. Seven subspecies.

other common names

French: Noctule; German: Abendsegler; Spanish: Nóctulo común.

physical characteristics

A medium-sized bat with yellowish to dark brown dorsal fur and slightly lighter-colored fur ventrally. Body length ranges from 2.6 to 3.2 in (6.5 to 8.2 cm), weight from about 0.53 to 1.23 oz (15 to 35 g), and forearm length from 1.9 to 2.3 in (4.7 to 5.8 cm).

distribution

Throughout Europe and much of temperate Asia, perhaps as far south as Singapore.

habitat

Forests and fields, often near water.

behavior

They migrate—sometimes more than 400 mi (670 km) and possibly much farther—to winter hibernation sites in caves, tree hollows, and building crevices. Hundreds may hibernate together. They frequently awaken during the winter and leave the hibernaculum in search of food. After the spring migration, groups may temporarily roost together in buildings, frequently emitting screeching trills that are audible to humans. The groups disperse, and individuals separate to roost in small tree hollows and rock crevices. Males become territorial during breeding season, and release pheromones to attract females.

feeding ecology and diet

Fly over open areas, foraging for winged insects, including moths and beetles.

reproductive biology

Mating commonly occurs both in early fall and in the spring; most likely polygynous. Delayed fertilization follows early mating, so that only one litter is produced in late spring to early summer. Gestation lasts 50–70 days. Litter size ranges from one to three altricial young per female, although three is rare. Weaned at six weeks of birth, the young reach full size at about two months old. Females may attain sexual maturity as early as three months of age, but most females and males do not become sexually active until the following year.

conservation status

Not listed by the IUCN, however, habitat destruction appears to be reducing their numbers.

significance to humans

Assist in controlling pest insect populations.

Evening bat

Nycticeius humeralis

subfamily

Vespertilioninae

taxonomy

Nycticeius humeralis (Rafinesque, 1818), Kentucky, United States.

other common names

English: Twilight bat, black-shouldered bat; French: Chauvesouris vespérale.

physical characteristics

Adults range from 3.5 to 4.3 in (9–11 cm) in body length, about 0.28–0.53 oz (8–15 g) in weight, and 1.3–1.5 in (3.3–3.9 cm) in forearm length. A medium-sized dark brown bat with short, black ears. It has a single pair of incisors, rather than two pair as are present in the similar appearing, although larger, big brown bat (Eptesicus fuscus). The dental formula is (I1/3 C1/1 P1/2 M3/3) × 2 = 30.

distribution

North America, including northeastern Mexico and about a third of the United States from the Gulf states to the Midwest and the mid-Atlantic coast states.

habitat

Forested areas.

behavior

Evening bats roost in tree crevices and buildings in the summer, and become active in early evening. Solitary animals, but females and their pups may gather in large, multi-family nursery colonies. Little is known about this species' migratory behavior, but they do accumulate fat stores before disappearing in the fall, indicating that they may migrate south. Cave surveys have not found evening bats, suggesting that this species either uses something other than caves for its hibernacula, or does not hibernate.

feeding ecology and diet

Evening bats begin foraging soon after sunset, seeking beetles, moths, flying ants, and other insects.

reproductive biology

Polygynous; mating occurs in the fall, with birth in early summer. Litter size is usually two naked young per female. The young begin to fly within a month of their birth, and are weaned at about two months old. Young males leave their mothers upon weaning, but females remain for at least a few more months.

conservation status

Not threatened.

significance to humans

Assist in controlling pest insect populations, notably the chrysomelid beetle. Its larvae, called the corn rootworm, is well-known to farmers for a destructive potential.

Eastern pipistrelle

Pipistrellus subflavus

subfamily

Vespertilioninae

taxonomy

Pipistrellus subflavus (F. Cuvier, 1832), Georgia, United States.

other common names

French: Pipistrelle de l'est.

physical characteristics

Adults range from 3 to 3.5 in (7.5–9 cm) in length, 0.18–0.28 oz (5–8 g) in weight, and 1.2–1.4 in (3.1–3.6 cm) in forearm length. Medium-sized, yellowish to reddish brown bat with an orangish forearm that is a start contrast to its dark wing. The individual dorsal hairs bear a characteristic yellowish patch in the middle. The dental formula is (I2/3 C1/1 P2/2 M3/3) × 2 = 34.

distribution

The eastern half of Mexico and the United States, except for much of Minnesota, Michigan, and southern Florida. Also extends into extreme southern Ontario and Quebec, and south to Honduras.

habitat

Wooded areas near water.

behavior

The eastern pipistrelle remains quite active all year in southern climates, but enters a deep hibernation in northern areas, usually opting to spend its winter in the same cave or mine from year to year. It is one of the first bats to hibernate, and awakens infrequently during the cold months. During the summer, this bat becomes active early in the evening, sometimes at sunset.

feeding ecology and diet

Diet includes small, flying insects, which the bat catches in flight, often swiping them up with its wing or tail membrane and drawing them to its mouth.

reproductive biology

Mating commonly occurs in early fall and spring, with delayed fertilization following the fall mating. Young are born in early summer. Gestation lasts at least 44 days. Litter size is typically two altricial young per female, although it can range from one to three. Weaned within a month of birth, the young begin flying before they reach one month old. Most likely polygynous.

conservation status

Not threatened.

significance to humans

Assist in controlling pest insect populations.

Brown long-eared bat

Plecotus auritus

subfamily

Vespertilioninae

taxonomy

Plecotus auritus (Linnaeus, 1758), Sweden.

other common names

English: Whispering bat; French: Oreillard brun; German: Braunes Langohr; Spanish: Orejudo septentrional.

physical characteristics

Adults range from 1.5 to 2 in (3.7–5 cm) in length, 0.18–0.42 oz (5–12 g) in weight, and 1.3–1.7 in (3.4–4.2 cm) in forearm length. Medium-sized, light-brown bat that rests with its long ears curled along its body or hidden beneath the wings. When outstretched, the ears are almost as long as the bat's body.

distribution

Throughout all but far southern Europe, east through temperate Asia to northern China and Nepal.

habitat

Open forests and park-like settings.

behavior

During the summer, they roost individually or in nursery colonies in tree crevices or in buildings. Males often join the nursery colonies. They leave the roost for nighttime feeding well after sunset. They typically enter hibernation in late fall, opting to spend the winter in small crevices in trees or man-made structures, although they will sometimes hibernate in caves.

feeding ecology and diet

A slow, but skillful flyer, this bat forages for insects in flight and by picking earwigs and spiders off of plants. Research has shown that this species uses taste and/or smell to select food items. Predators include ground mammals, such as house cats, that catch the bats while they are gleaning arthropods from vegetation.

reproductive biology

Promiscuous; mating commonly occurs in fall and spring, with delayed fertilization in early breeding females. Young are born in early summer. Litter size is typically one altricial young per female. The young begin flying before they reach one month old and are weaned at about a month-and-a-half. Females become sexually mature their first year, and males the following spring.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

A bio-indicator species that is particularly sensitive to pesticides.

Bamboo bat

Tylonycteris pachypus

subfamily

Vespertilioninae

taxonomy

Tylonycteris pachypus (Temminck, 1840), Java, Indonesia.

other common names

English: Club-footed bat, lesser flat-headed bat.

physical characteristics

Adults range from 1.6 to 2.4 in (4–6 cm) in length, 0.09–0.21 oz (2.5–6 g) in weight, and 0.8–1.2 in (2–3 cm) in forearm length. One of the smallest bats, the bamboo bat is brown to reddish dorsally, slightly lighter ventrally, and has a flattened head.

distribution

Southeast Asia from India to southern China and into Indonesia.

habitat

Bamboo forests.

behavior

Most notably, these bats are able to climb into and actually roost in internodal hollows of the large bamboo, Gigantochloa scortechinii. Their flattened skulls combined with small overall body size provide access to the tiny openings in the hollow stem joints, and pads on their thumbs and feet help them cling to the sides of the stems. Males may travel alone, with a few other males, or in transient harems of one male, several females, and numerous young.

feeding ecology and diet

Termites appears to be a preferred food item.

reproductive biology

Young are born in February to May. Gestation lasts about three months. Litter size is typically two altricial young per female. The young are weaned at about a month-and-a-half. Females and males become sexually mature their first year. Most likely polygynous.

conservation status

Not threatened.

significance to humans

Assist in controlling termite populations.

Daubenton's bat

Myotis daubentonii

subfamily

Vespertilioninae

taxonomy

Myotis daubentonii Kuhl, 1817, Hanau, Hessen, Germany.

other common names

English: Water bat; French: Vespertilion de Daubenton; German: Wasserfledermaus; Spanish: Murcielago ribereño.

physical characteristics

Adults range from 1.8 to 2.2 in (4.5–5.5 cm) in length, 0.25–0.42 oz (7–12 g) in weight, and 1.3–1.6 in (3.4–4.1 cm) in forearm length. Medium-sized brown bat with lighter ventral fur.

distribution

Eurasia.

habitat

Riparian areas, often near woods.

behavior

In addition to mother-and-young maternal roosts, adult males and females may roost together during the summer. Roosts are usually underground tunnels, cellars, and caves. They hibernate in the winter in similar underground locations, but remain quite active, leaving the hibernaculum frequently.

feeding ecology and diet

Often feeds in flight, capturing insects over water. Also known to occasionally take a small fish.

reproductive biology

Species most likely promiscuous. Mating commonly occurs in the fall and winter, with delayed fertilization. Young are born in early summer. Litter size is typically one. The young are weaned by two months of age.

conservation status

Not threatened.

significance to humans

May help control pest insect populations.

Resources

Books

Altringham, J. Bats: Biology and Behavior. Oxford: Oxford University Press, 1996.

Fenton, M. Bats. New York: Checkmark Books, 2001.

Kunz, T., and P. Racey, eds. Bat Biology and Conservation. Washington, DC: Smithsonian Institution Press, 1998.

Kurta, A. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press, 1995.

Nowak, R. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press, 1999.

Periodicals

Adams, R., and S. Pedersen, "Wings on Their Fingers." Natural History 103 (January 1994): 48–55

Arizona Game and Fish Department. "Antrozous pallidus." Unpublished abstract compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department. Phoenix: 1994.

Bradley, P. "Nevada's Night Fliers." Natural History 105 (February 1996): 72–6.

Milius, S. "Bat Bites Bird—In Migration Attacks." Science News 160, no. 6 (2001): 86.

Petit, E., L. Excoffier, and F. Mayer. "No Evidence of Bottleneck in the Postglacial Recolonization of Europe by the Noctule Bat (Nyctalus noctula)." Evolution 53, no. 4 (1999): 1247–1258.

Racey, P. "The Conservation of Bats in Europe." Bats 10, no. 4 (1992): 4–10.

Whitaker, John O., Jr. "Food of the Big Brown Bat Eptesicus fuscus from Maternity Colonies in Indiana and Illinois." The American Midland Naturalist 134 (1995): 346–360.

Organizations

Bat Conservation International. P.O. Box 162603, Austin, TX 78716 USA. Phone: (512) 327-9721. Fax: (512) 327-9724. E-mail: [email protected] Web site: <http://www.batcon.org>

The Bat Conservation Trust. 15 Cloisters House, 8 Battersea Park Rd., London, SW8 4BG UK. Phone: 020 7627 2629. Fax: 020 7627 2628. E-mail: [email protected] Web site: <http://www.bats.org.uk/aboutbct.htm>

The Organization for Bat Conservation at Cranbrook Institute of Science. 39221 Woodward Avenue, P.O. Box 801, Bloomfield Hills, MI 48303-0801 USA. Phone: (800) 276-7074. E-mail: [email protected] Web site: <http://batconservation.org/>

Leslie Ann Mertz, PhD