The
little brown bat (sometimes called
little brown myotis) (
Myotis lucifugus) is one of the most common
batBats are flying mammals in the order Chiroptera . The forelimbs of bats are webbed and developed as wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums and colugos, glide rather than...
s of
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
, a
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of the
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Myotis (
mouse-eared batThe mouse-eared bats, genus Myotis, are a genus of around 90 species of bat, found around the globe with 10 species in Europe.-Physical characteristics:Ears are normally longer than they are wide, with a long and lance-shaped tragus...
s), found throughout the world.
Description
As suggested by the bat’s name, its fur is uniformly dark brown and glossy on the back and upper parts with slightly paler, greyish fur underneath. Wing membranes are dark brown on a typical
wingspanThe wingspan of an airplane or a bird, is the distance from the left wingtip to the right wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent,...
of . Ears are small and black with a short, rounded tragus. Adult bats are typically long and weigh . All teeth including
molarsMolars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
are relatively sharp, as is typical for an
insectivoreAn insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures.Although individually small, insects exist in enormous numbers and make up a very large part of the animal biomass in almost all non-marine environments...
, and
canineIn mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
s are prominent to enable grasping hard-bodied
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s in flight.
Diet
Little brown bats are insectivores, eating moths, wasps, beetles, gnats, mosquitoes, midges and mayflies, among others. Since many of their preferred meals are insects with an aquatic life stage, such as mosquitoes, they prefer to roost near water. They
echolocateEcholocation, also called biosonar, is the biological sonar used by several animals such as dolphins, shrews, most bats, and most whales. The term was coined by Donald Griffin, who was the first to conclusively demonstrate its existence in bats...
to find their prey. Often they will catch larger prey with a wingtip, transfer it to a cup formed by their tail, then eat it - smaller prey are usually just caught in the mouth. They often use the same routes over and over again every night, flying 3-6 meters high above water or among trees. An adult can sometimes fill its stomach in 15 minutes; young have more difficulty. If they do not catch any food, they will enter a
torporDaily Torpor, sometimes called temporary hibernation is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds and some mammals such as mice, and bats...
similar to hibernation that day, awakening at night to hunt again.
Distribution
The little brown bat is found all over
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
from northern
MexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
to interior
AlaskaAlaska is the largest state of the United States of America by area; it is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
. It is the most abundant bat found in the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
and
CanadaCanada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...
.
Life Cycle
Since little brown bats live in a temperate zone, they must find some way of dealing with winter. Most temperate bats either migrate or hibernate, but little brown bats do both. In summer, the males and females live apart, the females raising young. When fall comes, both genders fly south to a hibernaculum, where they mate and then hibernate.
Little brown bats undergo a prolonged period of hibernation during the winter due to the lack of food. They hibernate in caves as a community. Little brown bats mate in the autumn, before hibernation begins, and over winter the male's sperm is stored inside the female's body, and the infant is conceived in spring. When they arise in the spring, the females go to nursery colonies which may often be the same place where they were born.
These nursery colonies consist mainly of adult females and their young and can be located in the attics of warm buildings where there is high humidity. Gestation is 50-60 days. They usually have one baby per female each year, sometimes
twinTwins are two offspring resulting from the same pregnancy, usually born in close succession. They can be the same or different sex. Twins can either be monozygotic or dizygotic ....
s, born sometime from late May to early July. The young are born in an altricial state with their eyes closed and will hang in the nursery while their mothers forage at night. Their eyes open on their second day. They cling to a nipple constantly until they are two weeks old. At 3 weeks, they learn to fly. By 4 weeks, they are adult size.
The number of males in the nursery increases in September, and in October all of the bats migrate back to the caves to hibernate. They use the same hibernaculum and summer colonies year after year, except for yearling males going to the male summer colony upon reaching adulthood. While the females are at the nursing colonies during the summer, males roost in small groups in rock crevices or tree hollows.
Females may be sexually mature in the fall after their birth, but males may take a year longer. About half of females and most males breed in their first autumn. They can live up to 33 years, males living longer on average, though the average
lifespanLife expectancy is the expected number of years of life remaining at a given age. It is denoted by e
x, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...
is shorter since about 50% of little brown bats die in their first year.
Social Status
The nursery colonies sometimes get to numbers as big as 1000 bats in one cave/forest.
Endangered Status
Little brown bats are not listed as endangered and have no special
conservation statusThe conservation status of a species is an indicator of the likelihood of that species remaining extant either in the present day or the near future...
. Man-made roosting areas such as attics, caves and mines assist their particular abundance. Many states, though, have made special considerations for brown bats including listing them as a sensitive or protected species. Little brown bats are now at a higher threat due to
white nose syndromeWhite nose syndrome is a poorly understood malady associated with the deaths of hundreds of thousands of bats. The condition, named for a distinctive ring of fungal growth around the muzzles, and on the wings of many affected animals, was first identified in a cave in Schoharie County, New York in...
in eastern North America.
Genome Projects
The genome of
M. lucifugus has already been sequenced at low (2x) coverage for the Mammalian Genome Project. It has also been selected for more complete (approximately 7x coverage) genome sequencing. This species is also part of the ENCODE comparative sequencing project.
External links