Big Brown Bat
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The big brown bat (''Eptesicus fuscus'') is a species of
vesper bat Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat famili ...
distributed widely throughout North America, the
Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
, and the northern portion of South America. It was first described as a species in 1796. Compared to other microbats, the big brown bat is relatively large, weighing and possessing a wingspan of . Big brown bats are
insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...
, consuming a diverse array of insects, particularly night-flying insects, but especially
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s. Some of the beetles it consumes are serious agricultural pests, including cucumber beetles. They are
nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...
, foraging for prey at night and roosting in sheltered areas during the day such as caves, tunnels, tree cavities, and human structures. Their breeding season is in the fall, shortly before their annual hibernation. After hibernation ends in the spring, females form maternity colonies for giving birth to young. Oftentimes only one offspring is produced per litter, though twins are common in the Eastern US. Lifespans of 6.5 years are considered average. The big brown bat occurs widely throughout the US, Canada, Central America, and the Caribbean. Its range extends into parts of South America, found as far south as Colombia and Venezuela. It is adaptable to many habitats and is considered a
generalist species A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different natural resource, resources (for example, a heterotroph with a varied diet (nutrition), diet). A specialist species can ...
. The big brown bat is not considered at risk for extinction, and is evaluated as the lowest conservation priority by the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
(IUCN). While some other bat species in its range have experienced dramatic population declines due to the fungal disease
white-nose syndrome White-nose syndrome (WNS) is a fungal disease in North American bats which has resulted in the dramatic decrease of the bat population in the United States and Canada, reportedly killing millions as of 2018. The condition is named for a distinctiv ...
, the big brown bat is relatively resistant to the effects of the disease, and some populations have even increased since the syndrome arrived in North America. Like all bats in the US, the big brown bat can be impacted by
rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abn ...
, though some individuals have immunity against the virus. Even though sick bats are more likely to be submitted for testing, in 2011, only 3.8% of submitted big brown bats were positive for the rabies virus. Bat boxes are sometimes used to attract them as they are an agriculturally valuable species.


Taxonomy and etymology

The big brown bat was described in 1796 by French naturalist
Palisot de Beauvois Ambroise Marie François Joseph Palisot, Baron de Beauvois (27 July 1752, in Arras – 21 January 1820, in Paris) was a French naturalist and zoologist. Palisot collected insects in Oware, Benin, Saint Domingue, and the United States, from 17 ...
. Palisot described the species based on specimens in the Philadelphia Museum of
Charles Willson Peale Charles Willson Peale (April 15, 1741 – February 22, 1827) was an American painter, military officer, scientist, and naturalist. In 1775, inspired by the American Revolution, Peale moved from his native Maryland to Philadelphia, where he set ...
, an American naturalist, giving it the name ''Vespertila fuscus''. The genus name, ''Eptesicus'', is likely derived from the Greek words ''ptetikos'' ("able to fly") or ''petomai'' ("house flier"), and the
species name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
"'' fuscus''" is
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
in origin, meaning "brown". The big brown bat is the
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
for the genus ''Eptesicus'', which was established in 1820 by French-American naturalist
Constantine Samuel Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...
. Though Rafinesque designated the type species as ''Eptesicus melanops'', this was later determined to be a synonym of ''Eptesicus fuscus''. The first use of the current name combination ''Eptesicus fuscus'' was in 1900 by Hungarian zoologist
Lajos Méhelÿ Lajos Méhelÿ (August 24, 1862 – February 4, 1953) was a Hungarian zoologist, herpetologist, professor, and author. He remains controversial due to his Social Darwinist and racialist publications. He was a member of the Hungarian Academy of Sc ...
. Recognized subspecies number eleven or twelve: ''E. f. lynni'' has sometimes been considered a full species, though was listed as a subspecies by the
American Society of Mammalogists The American Society of Mammalogists (ASM) was founded in 1919. Its primary purpose is to encourage the study of mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence ...
and the
Integrated Taxonomic Information System The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...
(ITIS) as of 2019. In the US state of
Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
where two subspecies were hypothesized to overlap (''E. f. fuscus'' and ''E. f. pallidus''), morphological features did not agree with genetic lineages, and thus were not reliable in distinguishing the two subspecies. Individuals with eastern and western US genetic lineages co-occurred in the same colonies, however. As the genus ''
Eptesicus ''Eptesicus'' is a genus of bats, commonly called house bats or serotine bats, in the family Vespertilionidae. The genus name is likely derived from the Greek words ''ptetikos'' 'able to fly' or ''petomai'' 'house flier', although this is not cer ...
'' is fairly speciose, it is further divided into morphologically similar " species-groups". The big brown bat belongs to the ''serotinus'' group, which is defined by having a large, elongate skull, flat braincase, and a long
snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...
. In a study of the evolutionary relationships of some ''Eptesicus'' species, the big brown bat was most closely related to the two other species from the Americas: the Argentine brown bat and the diminutive serotine. The ''serotinus'' group also includes: * Little black serotine, ''E. andinus'' * Botta's serotine, ''E. bottae'' *
Brazilian brown bat The Brazilian brown bat (''Eptesicus brasiliensis'') is a bat species from South America, South and Central America. Description The Brazilian brown bat is medium in size, being long, and has forearms that are long. It has a long tail and tr ...
, ''E. brasiliensis'' * Diminutive serotine, ''E. diminutus'' * Argentine brown bat, ''E. furinalis'' * Long-tailed house bat, ''E. hottentotus'' * Harmless serotine, ''E. innoxius'' * Meridional serotine, ''E. isabellinus'' * Lagos serotine, ''E. platyops'' * Serotine bat, ''E. serotinus'' * Sombre bat, ''E. tatei''


Description

It is a relatively large
microbat Microbats constitute the suborder Microchiroptera within the order Chiroptera (bats). Bats have long been differentiated into Megachiroptera (megabats) and Microchiroptera, based on their size, the use of echolocation by the Microchiroptera an ...
, weighing . Adult body length is . Its forearm is usually longer than . The tail is and the hind legs are . Its wingspan is . Its
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
fur is reddish brown and glossy in appearance; its
ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
fur is lighter brown. Its snout,
uropatagium The patagium (: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flying. The structure is found in extant and extinct groups of flying and gliding animals including bats, theropod dinosaurs (including b ...
(flight membrane between the hind limbs), and wing membranes are black and hairless. Its ears () are also black; they are relatively short with rounded tips. The tragi (cartilage flaps in front of the ear canal) also have rounded tips. It has a robust
skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...
; the greatest length of the skull is approximately . The snout has a rounded and somewhat flattened appearance. The
braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calv ...
has a breadth of approximately and the
mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...
(jawbone) has a length of approximately . The upper incisors are large, with the inner pair more prominent than the outer pair. The inner pair of upper incisors also has a distinctive secondary cusp. The crowns of the lower incisors are trifid, or have three cusps. Its
dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...
is , for a total of 32 teeth.


Biology


Diet

Big brown bats are
insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...
, eating many kinds of insects including
beetles Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
,
flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...
, stone flies,
mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...
,
true bugs Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, Cimex, bed bugs, and shield bugs. They ...
, net-winged insects,
scorpionflies Mecoptera (from the Greek language, Greek: ''mecos'' = "long", ''ptera'' = "wings") is an Order (biology), order of insects in the superorder Holometabola with about six hundred species in nine Family (biology), families worldwide. Mecopterans a ...
,
caddisflies The caddisflies (order Trichoptera) are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis ...
, and
cockroaches Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...
. It will forage in cities around street lamps. As the big brown bat is such a widespread species, it has regional variation in its diet, though it is generally considered a beetle specialist. Populations in
Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...
and
Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
have particularly high consumption of scarab beetles, cucumber beetles, ground beetles and shield bugs. In
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
, primary prey items include
moths Moths are a group of insects that includes all members of the order Lepidoptera that are not butterflies. They were previously classified as suborder Heterocera, but the group is paraphyletic with respect to butterflies (suborder Rhopalocera) a ...
in addition to scarab beetles and ground beetles. In
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
, large proportions of caddisflies are consumed, with flies as a secondary prey source. A study in
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
compared fecal samples of big brown bats with the abundance of insects collected in passive traps. The result was a strong preference for beetles as prey.
Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
were the most common insect order collected but beetles were present in 99.2% of fecal samples. When being rehabilitated, big brown bats are often fed
mealworm Mealworms are the larval form of the yellow mealworm beetle, ''Tenebrio molitor'', a species of darkling beetle. The yellow mealworm beetle prefers a warmer climate and higher humidity. Male mealworm beetles release a sex pheromone to attract ...
s which have been supplemented with necessary vitamins and minerals. Big brown bats are significant predators of agricultural pests. A 1995 study found that, per year, a colony of 150 big brown bats in Indiana or Illinois consumes 600,000 cucumber beetles, 194,000 scarab beetles, 158,000
leafhopper Leafhopper is the common name for any species from the family (biology), family Cicadellidae: based on the type genus ''Cicadella''. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or ...
s, and 335,000 shield bugsall of which cause serious agricultural damage.


Behavior

The big brown bat is
nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...
, roosting in sheltered places during the day. It will utilize a wide variety of structures for roosts, including mines, caves, tunnels, buildings, bat boxes, tree cavities,
storm drain A storm drain, storm sewer (United Kingdom, U.S. and Canada), highway drain, surface water drain/sewer (United Kingdom), or stormwater drain (Australia and New Zealand) is infrastructure designed to drain excess rain and ground water from i ...
s, wood piles, and rock crevices. They generally roost in cavities, though they can sometimes be found under exfoliating bark. Both solitary males and solitary, non-pregnant/non-lactating females have been found roosting under bark. In the summer, males are most often solitary, though they may form small, all-male colonies. Males will also sometimes roost with adult females. Females exhibit
philopatry Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derives ...
("love of place"), with 10-30% of female offspring returning to their natal roost the following year and up to 72% of adult females using the same roost in subsequent years. Like many other species of microbats, the big brown bat often uses echolocation to navigate. This means that the species emits a call out into its environment and listens to the echoes of those calls that return from various objects near them. Using echolocation, big brown bats can determine how far away an object is, the objects size, shape and density, and the direction (if any) that an object is moving. Their use of echolocation allows them to occupy a niche where there are often many
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s (that come out at night since there are fewer predators then), less competition for food, and fewer species that may prey on the big brown bat itself.


Reproduction and life expectancy

Big brown bat
mating season Seasonal breeders are animal species that successfully mate only during certain times of the year. These times of year allow for the optimization of survival of young due to factors such as ambient temperature, food and water availability, and ch ...
is in the fall. After the breeding season, pregnant females separate into maternity colonies around April. Maternity colonies range in size from 5-700 individuals, though in the eastern US and Canada, they are frequently 25-75 adults. Historically, maternity colonies were probably in tree cavities. In modern, human-dominated landscapes, however, many maternity colonies are in buildings. In the eastern United States, twins are commonly born sometime between May and July; in western North America, females give birth to only one pup each year. A dissected female was once found with four
embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
s; had the female given birth, though, it is unlikely that all four would have survived. Like most species of bat, the big brown bat only has two nipples. At birth, pups are blind, helpless, and only , though they grow quickly, gaining up to per day. The pup nurses from its mother for approximately one month. Mothers leave their pups behind at the roost while they forage at night. Pups fledge, or begin flying, at three to five weeks old. A 2011 study of a population in Colorado found that their average life expectancy was a little over 6.5 years; according to a 2008 report, some banded big brown bats have lived up to 20 years, although some experts have hypothesized that the bats might be "capable of living much longer." In general, males live longer than females.


Hibernation

Big brown bats enter into hibernation around November, often in a location less than away from their summer roosts. Big brown bats often hibernate by themselves, or in small groups. While some big brown bats hibernate in
subterranean Subterranean(s) or The Subterranean(s) may refer to: * Subterranea (geography), underground structures, both natural and man-made Literature * ''Subterranean'' (novel), a 1998 novel by James Rollins * ''Subterranean Magazine'', an American fa ...
locations such as caves and underground mines, most can be found in warm man-made structures. Big brown bats tolerate cold weather fairly well, although they can be negatively affected by major changes in temperature. It is fairly common for some hibernating big brown bats to awaken temporarily and seek warmer shelter, locate water, and even mate. Big brown bats come out of hibernation in the spring. The big brown bat has large deposits of
brown fat Brown adipose tissue (BAT) or brown fat makes up the adipose organ together with white adipose tissue (or white fat). Brown adipose tissue is found in almost all mammals. Classification of brown fat refers to two distinct cell populations with si ...
, which provides the bats with a source of energy to rapidly increase body temperature upon arousal from hibernation. In the summer, big brown bats substantially reduce their brown fat deposits, which are less than half of their winter size.


Predators, parasites, and disease

The big brown bat has few natural predators. Predation occurs opportunistically, with
common grackle The common grackle (''Quiscalus quiscula'') is a species of large icterid bird found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a ...
s,
American kestrel The American kestrel (''Falco sparverius'') is the smallest and most common falcon in North America. Though it has been called the American sparrowhawk, this common name is a misnomer; the American kestrel is a true falcon, while neither th ...
s,
owls Owls are birds from the Order (biology), order Strigiformes (), which includes over 200 species of mostly Solitary animal, solitary and Nocturnal animal, nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vis ...
,
long-tailed weasel The long-tailed weasel (''Neogale frenata''), also known as the bridled weasel, masked ermine, or big stoat, is a species of weasel found in North America, North, Central America, Central, and South America. It is distinct from the Stoat, short-t ...
s, and
American bullfrog The American bullfrog (''Lithobates catesbeianus''), often simply known as the bullfrog in Canada and the United States, is a large true frog native to eastern North America. It typically inhabits large permanent water bodies such as swamps, po ...
s as known predators. It is affected by a number of
ectoparasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s (external parasites) and
endoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...
s (internal parasites). Insect ectoparasites include '' Basilia'' (flies), ''
Cimex ''Cimex'' is a genus of insects in the family Cimicidae. ''Cimex'' species are ectoparasites which typically feed on the blood of birds and mammals. Two species, ''Cimex lectularius'' and ''Cimex hemipterus'', are known as bed bugs and frequentl ...
'' (true bugs), and '' Myodopsylla'' (fleas). Several
mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s are ectoparasites as well, including '' Acanthopthirius'', '' Cheletonella'', '' Euschoengastia'', '' Leptotrombidium'', '' Macronyssus'', '' Neospeleognathopsis'', '' Neotrombicula'', '' Olabidocarpus'', ''
Ornithodoros ''Ornithodoros'' is a genus in the soft-bodied tick family, Argasidae. It is distinguished from other genera in the family by the absence of a lateral 'suture' line. It is the largest genus within Argasidae, consisting of approximately 130 specie ...
'', '' Parasecia'', '' Perissopalla'', and '' Spinturnix''. Endoparasites include
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s,
cestode Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies co ...
s, and
trematode Trematoda is a Class (biology), class of flatworms known as trematodes, and commonly as flukes. They are obligate parasite, obligate Endoparasites, internal parasites with a complex biological life cycle, life cycle requiring at least two Host ( ...
s. Like all bats in the United States, big brown bats can be affected by
rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abn ...
. The
incubation period Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or ionizing radiation, radiation, and when symptoms and signs are first apparent. In a typical infect ...
for rabies in this species can exceed four weeks, though the mean incubation period is 24 days. Rabid big brown bats will bite each other, which is the primary method of transmission from individual to individual. However, not all individuals will develop rabies after exposure to the virus. Some individuals have been observed with a sufficiently high rabies
antibody An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
concentration to confer
immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity ...
. Rabies immunity can be passed from mother to pup via
passive immunity In immunology, passive immunity is the transfer of active humoral immunity of ready-made antibodies. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced arti ...
or from exposure to the bite of a rabid individual. Overall, a low proportion of big brown bats become infected with rabies. Populations of big brown bats in the Eastern United States have a different strain of rabies than the populations in the Western United States. In one study, only 10% of big brown bats were shedding the rabies virus through their saliva before exhibiting clinical symptoms of the disease; symptoms of rabies in big brown bats include acute weight loss, paralysis,
ataxia Ataxia (from Greek α- negative prefix+ -τάξις rder= "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in e ...
(inability to coordinate muscle movement),
paresis In medicine, paresis (), compound word from Greek , (πᾰρᾰ- “beside” + ἵημι “let go, release”), is a condition typified by a weakness of voluntary movement, or by partial loss of voluntary movement or by impaired movement. Whe ...
(weakness of voluntary movement), and unusual vocalizations.


Range and habitat

The big brown bat is encountered widely throughout North America in present times. It is found from southern Canada and Alaska to as far south as Colombia and Venezuela. It has also been documented in the Caribbean in both the Greater and
Lesser Antilles The Lesser Antilles is a group of islands in the Caribbean Sea, forming part of the West Indies in Caribbean, Caribbean region of the Americas. They are distinguished from the larger islands of the Greater Antilles to the west. They form an arc w ...
, including
Cuba Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...
,
Hispaniola Hispaniola (, also ) is an island between Geography of Cuba, Cuba and Geography of Puerto Rico, Puerto Rico in the Greater Antilles of the Caribbean. Hispaniola is the most populous island in the West Indies, and the second-largest by List of C ...
,
Dominica Dominica, officially the Commonwealth of Dominica, is an island country in the Caribbean. It is part of the Windward Islands chain in the Lesser Antilles archipelago in the Caribbean Sea. The capital, Roseau, is located on the western side of t ...
,
Barbados Barbados, officially the Republic of Barbados, is an island country in the Atlantic Ocean. It is part of the Lesser Antilles of the West Indies and the easternmost island of the Caribbean region. It lies on the boundary of the South American ...
, and the
Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...
. The big brown bat has been documented from above sea level. It is a generalist, capable of living in urban, suburban, or rural environments. It has been called "the most widespread
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
bat in North America", as it is more represented in the fossil record of that time than any other bat species. Its extensive fossil record is known from more than thirty sites, including fourteen US states, Puerto Rico, Mexico, and the Bahamas.


Conservation

The big brown bat is evaluated at the lowest conservation priority by the
IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
. It meets the criteria for this designation because it has a wide geographic distribution, a large population size, occurrence in protected areas, and tolerance to habitat modification by humans. While other bat species in the Eastern United States have experienced significant population declines (up to 98% loss) due to
white-nose syndrome White-nose syndrome (WNS) is a fungal disease in North American bats which has resulted in the dramatic decrease of the bat population in the United States and Canada, reportedly killing millions as of 2018. The condition is named for a distinctiv ...
, the big brown bat is relatively resistant to its effects. Even in caves harboring ''
Pseudogymnoascus destructans ''Pseudogymnoascus destructans'' (formerly known as ''Geomyces destructans'') is a Psychrophile, psychrophilic (cold-loving) fungus that causes white-nose syndrome (WNS), a fatal disease that has devastated bat populations in parts of the United ...
'', the fungus that causes white-nose syndrome, big brown bats maintain normal
torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the ti ...
patterns. Unlike in other species more affected by white-nose syndrome, big brown bats are able to retain more of their body fat throughout hibernation. In fact, some regions of the eastern United States have seen an increase in big brown bat populations since the arrival of white-nose syndrome.


Relationship to people

The big brown bat is the official state mammal of the
District of Columbia Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and Federal district of the United States, federal district of the United States. The city is on the Potomac River, across from ...
.


Economic value

Big brown bats are a species that will use bat houses for their roosts. Landowners will purchase or construct bat houses and install them, hoping to attract big brown bats, largely due to their being an "agriculturally valuable species". In particular, the big brown bat feeds on cucumber beetles, which can decimate corn; this makes the species quite beneficial to farmers in the
Corn Belt The Corn Belt is a region of the Midwestern United States and part of the Southern United States that, since the 1850s, has dominated corn production in the United States. In North America, ''corn'' is the common word for maize. More genera ...
.


As disease vectors

Big brown bats can be of concern to
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the de ...
as a rabies vector, as they commonly roost in buildings and thus have a higher chance of encountering humans. Because they are often found in proximity to humans, the big brown bat and the not-closely related
little brown bat The little brown bat or little brown myotis (''Myotis lucifugus'') is an endangered species of mouse-eared bat, mouse-eared microbat found in North America. It has a small body size and glossy brown fur. It is similar in appearance to several ...
are the two bat species most frequently submitted for rabies testing in the United States. Big brown bats infrequently test positive for the rabies virus; of the 8,273 individuals submitted for testing across the United States in 2011, 314 (3.8%) tested positive for the virus. There is a known bias in testing, however, as healthy bats rarely come into contact with humans, and therefore sick bats are more likely to be tested. In the US, human rabies cases from exposure to bats more frequently come from other bat species. Of the twenty-four human rabies cases from bats from 1993 to 2000, seventeen cases (71%) were a rabies variant associated with the
silver-haired bat The silver-haired bat (''Lasionycteris noctivagans'') is a solitary migratory species of vesper bat in the family Vespertilionidae and the monotypic, only member of the genus ''Lasionycteris''. Etymology The species name translates as night-wand ...
(''Lasionycteris noctivagans'') while one case (4%) was associated with the rabies variant found in big brown bats. ''
Histoplasma capsulatum ''Histoplasma capsulatum'' is a species of dimorphic fungus. Its sexual form is called ''Ajellomyces capsulatus''. It can cause pulmonary and disseminated histoplasmosis. ''Histoplasma capsulatum'' is "distributed worldwide, except in Antarc ...
'', the fungus that causes the disease
histoplasmosis Histoplasmosis is a fungal infection caused by ''Histoplasma capsulatum''. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can ...
, is occasionally found in its
guano Guano (Spanish from ) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertiliser due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a le ...
. The big brown bat may also be a vector of the Saint Louis encephalitis virus, a
mosquito Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...
-born virus that can affect humans. Individuals have also tested positive for ''
West Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family ''Flaviviridae'', from the genus ''Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The virus ...
'', which can also be transferred to humans via mosquitoes.


See also

*
Bats of Canada There are eighteen indigenous species of bats in Canada, which are found in many parts of the country. They are insectivores, and are prey to falcons, hawks, owls, snakes, cats, and raccoons.Health Canada Species The little brown bat is the mos ...
*
Bats of the United States All bat species in the United States are insectivorous except for three nectar-eating species that migrate from Mexico and one fruit-eating species that inhabits the Florida Keys. Species Bats belong to the biological order of Chiroptera. Th ...
*
Brown long-eared bat The brown long-eared bat or common long-eared bat (''Plecotus auritus'') is a small Eurasian insectivorous bat. It has distinctive ears, long and with a distinctive fold. It is extremely similar to the much rarer grey long-eared bat which was ...
*
Little brown bat The little brown bat or little brown myotis (''Myotis lucifugus'') is an endangered species of mouse-eared bat, mouse-eared microbat found in North America. It has a small body size and glossy brown fur. It is similar in appearance to several ...
, a similarly named bat belonging to the ''
Myotis The mouse-eared bats or myotises are a diverse and widespread genus (''Myotis'') of bats within the family Vespertilionidae. The noun "''myotis''" itself is a Neo-Latin construction, from the Greek "''muós'' (meaning "mouse") and "''oûs''" ( ...
''
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...


Notes


References


External links

* {{Authority control Articles containing video clips Big Brown Big Brown Big Brown Eptesicus Mammals described in 1796 Mammals of Colombia Mammals of the Dominican Republic Taxa named by Palisot de Beauvois