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The tricolored bat (''Perimyotis subflavus'') or American perimyotis is a species of
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 ...
native to eastern North America. Formerly known as the eastern pipistrelle, based on the incorrect belief that it was closely related to European ''
Pipistrellus ''Pipistrellus'' is a genus of bats in the family Vespertilionidae and subfamily Vespertilioninae. The name of the genus is derived from the Italian word , meaning "bat" (from Latin "bird of evening, bat"). The size of the genus has been co ...
'' species, the closest known relative of the tricolored bat is now recognized as the canyon bat. Its common name "tricolored bat" derives from the coloration of the hairs on its back, which have three distinct color bands. It is the smallest bat species in the eastern and midwestern US, with individuals weighing only . This species mates in the fall before hibernation, though due to sperm storage, females do not become pregnant until the spring. Young are born helpless, though rapidly develop, flying and foraging for themselves by four weeks old. It has a relatively long lifespan, and can live nearly fifteen years. In the summer, females roost in small groups and males roost solitarily in tree foliage or beard lichen. It eats a diverse array of insects, foraging with a slow, erratic flight and navigating via echolocation. Though once considered one of the most common bat species in its range, its populations have declined rapidly since 2006 with the introduction of the fungal disease white-nose syndrome. It was listed as an endangered species in 2012 in Canada, and has been petitioned for inclusion on the US endangered species list. Along 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 ...
, the tricolored bat is one of two bat species whose
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 ...
variants have most frequently been implicated in human rabies deaths in the US, with sixteen deaths from 1958–2000.


Taxonomy

The tricolored bat was described as a new species in 1832 by French zoologist
Frédéric Cuvier Georges-Frédéric Cuvier (; 28 June 1773 – 24 July 1838) was a French zoologist and paleontology, paleontologist. He was the younger brother of noted natural history, naturalist and zoologist Georges Cuvier. Career Frederic was the head keepe ...
, who placed it in the genus '' Vespertilio'' with a scientific name of ''Vespertilio subflavus''. The
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
had been collected in the US state of
Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...
by American naturalist
John Eatton Le Conte John Eatton Le Conte Jr. (sometimes John Eatton LeConte or John Eaton Leconte) (February 22, 1784 – November 21, 1860) was an American natural history, naturalist. He was born near Shrewsbury, New Jersey, Shrewsbury, New Jersey, the son o ...
. In 1897, American zoologist Gerrit Smith Miller Jr. placed it in the genus ''
Pipistrellus ''Pipistrellus'' is a genus of bats in the family Vespertilionidae and subfamily Vespertilioninae. The name of the genus is derived from the Italian word , meaning "bat" (from Latin "bird of evening, bat"). The size of the genus has been co ...
'' for the first time as a result of its physical similarities to other members of the genus. Its common name was thus the "eastern pipistrelle". In 1984 its status was reviewed, with H. Menu concluding that it was more similar in appearance to species in the genus '' Myotis'' rather than ''Pipistrellus'', erecting a new genus for the
taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
: ''Perimyotis''. The name "''Perimyotis''" means "around ''Myotis''", alluding to its similarities with the genus. This classification was not immediately accepted, however, with a 1985 study instead grouping it and the canyon bat into the genus '' Parastrellus'' and a 1987 publication maintaining that the tricolored bat was part of the ''Pipistrellus'' genus, though they listed ''Perimyotis'' as one of seven
subgenera In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...
. However, in 2003, a genetic study concluded that the tricolored bat was distinct from ''Pipistrellus'' species (and the canyon bat), confirming the validity of the genus ''Perimyotis''. Usage of the scientific name ''Perimyotis subflavus'' is widely accepted as of 2019. Its common name was changed from "eastern pipistrelle" to "tricolored bat" to reflect its revised classification. A 2010 study found that the
sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...
of the tricolored bat is the canyon bat, with the authors suggesting that these two genera form a
tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...
, though declining to name and formally describe the tribe. Instead, they referred to it as the "perimyotine group", which they gave as the most basal member of a clade that also included the following tribes: Nycticeiini, Eptesicini, Vespertilioni, and another unnamed tribe referred to as the "hysugine group" (including '' Chalinolobus'', '' Hypsugo'', '' Laephotis'', '' Neoromicia'', '' Nycticeinops'', '' Tylonycteris'', and '' Vespadelus''). The tribe was later described as Perimyotini. Its
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 ...
"''subflavus''" means "a little less than yellow", meaning yellowish or pale yellow. Four
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
are recognized: *''P. s. clarus'' (Baker, 1954) *''P. s. floridanus'' (Davis, 1957) *''P. s. subflavus'' (Cuvier, 1832) *''P. s. veraecrucis'' (Ward, 1891)


Description

The tricolored bat has blond fur that is distinctly tricolored on its back. Individual hairs tricolored: dark gray at the base, buffy (yellowish brown) in the middle, and brown or reddish brown at the tip. It is the smallest bat species found in the eastern and midwestern US. Individuals have a forearm length of and weigh . Its forearms are reddish, contrasting sharply with the black membranes of its wings. Its wingspan is . It has a
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 ...
of for a total of 34 teeth.


Biology and ecology


Reproduction and life cycle

The tricolored bat is a seasonal breeder, with copulation (mating) occurring in the fall before hibernation.
Ovulation Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...
does not occur until the spring, however, and females store the males'
sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...
in their
uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...
es through the winter.
Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...
(pregnancy) length is about forty-four days, with females giving birth in June or July. The litter size is typically two individuals. As newborns, the combined mass of twin pups can be as great as 58% of the mother's postpartum mass. At birth, the young lack fur and their eyes are closed. The mother leaves the offspring behind at the roost while she forages at night. Offspring develop rapidly, beginning to fly at three weeks old. By four weeks old, they are foraging for themselves. Young do not reach sexual maturity in their first fall; they do not breed until their second fall. Individuals can live at least 14.8 years in the wild; juveniles have higher mortality rates than adults, and females have higher mortality rates than males.


Behavior

During the summer, the tricolored bat will roost in tree foliage or buildings, with females alone or in maternity colonies of up to thirty individuals. Trees used for this purpose include
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
,
maple ''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated si ...
, the eastern cottonwood, and American tulip tree. Males are solitary and do not form colonies. In
Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
, researchers discovered nearly one hundred roosts of this species, finding that all sampled individuals were roosting not in tree foliage, but rather in a species of beard lichen, '' Usnea trichodea''. This was thought to be the first documentation of a bat using beard lichen as a roosting substrate. It was speculated that the tricolored bat may use the lichen to ward off parasites. Usnic acid, which has anti-insect and anti-bacterial properties, naturally occurs in beard lichens, and no ectoparasites (external parasites) have been documented on the tricolored bat in Nova Scotia. In the winter, the tricolored bat hibernates in mines, caves, or other human structures. A years-long study of a mine in the US state of Nebraska found that in the summer, the mine was mostly occupied by males. Total number of tricolored bats using the mine at one time ranged from zero to forty-three. Bats were in a state of
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 ...
from November to April. More bats used the mine as a roost in the winter than in the summer. In another abandoned mine in the US state of Indiana, researchers found that the tricolored bat roosts solitarily during hibernation for the majority of the time (96.8% of observations were singletons). During hibernation, males lose an average of , while females lose an average of .


Diet and foraging

The tricolored bat is
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 small prey of in length. Prey taxa include
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 ...
es,
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,
ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...
s,
moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...
s, and
cicada The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...
s. It forages with slow, erratic flight in areas near water or forest edges. It is one of the first bat species to begin foraging each night. It navigates and searches for prey via echolocation (sonar). Its echolocation calls are at a high frequency; visual renderings of the calls show a distinctive hook-shaped call profile, with the lowest frequencies (bottom of the hook shape) at 42 k Hz.


Predators, parasites, and disease

The tricolored bat's natural predators include the
northern leopard frog ''Lithobates pipiens''Integrated Taxonomic Information System nternet2012''Lithobates pipiens'' pdated 2012 Sept; cited 2012 Dec 26Available from: www.itis.gov/ formerly ''Rana pipiens'', commonly known as the northern leopard frog, is a s ...
, birds of prey,
raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the North American, northern or common raccoon (also spelled racoon) to distinguish it from Procyonina, other species of raccoon, is a mammal native to North America. It is the largest ...
s, snakes,
skunk Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or gi ...
s, and
prairie vole The prairie vole (''Microtus ochrogaster'') is a small vole found in central North America. Description The vole has long, coarse grayish-brown fur on the upper portion of the body and yellowish fur on the lower portion of the body. It has sh ...
s. Feral cats will also catch and kill them as they leave their hibernacula (cave or mine used for hibernation). There are also records of it being attacked by the hoary bat. The tricolored bat is the host to several species of endoparasites (internal parasites) and ectoparasites. Oocysts (spores) of an ''
Eimeria ''Eimeria'' is a genus of apicomplexan parasites that includes various species capable of causing the disease coccidiosis in animals such as cattle, poultry and smaller ruminants including sheep and goats. ''Eimeria'' species are considered to ...
'' species ('' Eimeria heidti'' ) have been recovered from 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 ...
(feces). The tricolored bat has experienced severe population decline as a result of the fungal disease white-nose syndrome, which arrived in the US in 2006, with losses of 70% and greater detected in multiple US states. The disease kills bats by colonizing their skin during the winter, causing them to arouse from torpor and burn through their limited fat reserves. Though its population experienced dramatic reduction, subsequent studies have found that their numbers may be stabilizing, though hibernacula where many individuals once roosted may only host fewer than five bats, or even one solitarily.


Range and habitat

The tricolored bat is common throughout eastern North America, with the southern extent of its range in Central America and the northern extent in southern Canada. Its range has expanded since the 1980s, with westward expansion reaching the US states of Colorado, New Mexico, South Dakota, and Wyoming. Additionally, its range started to include the Great Lakes Basin.


Conservation

As of 2018, it is listed as a
vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...
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 ...
. In 2008, however, it was considered a
least-concern species 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 ...
, which is the IUCN's lowest conservation priority. In the time between the two assessments, the fungal disease white-nose syndrome became widespread in eastern North America, severely impacting the tricolored bat. Historically, it was one of the most common bat species of eastern North America. After an emergency assessment, the tricolored bat is considered an endangered species under the Committee on the Status of Endangered Wildlife in Canada as of 2012. In 2016, the Center for Biological Diversity and Defenders of Wildlife submitted a petition to the
United States Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is a List of federal agencies in the United States, U.S. federal government agency within the United States Department of the Interior which oversees the management of fish, wildlife, ...
(USFWS) to list the tricolored bat under the
Endangered Species Act of 1973 The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...
. The USFWS determined that the petition demonstrated that listing the species as "threatened" or "endangered" may be warranted. In September 2022, the USFWS announced it would protect the bat as endangered under the Endangered Species Act, following a lawsuit from the Center for Biological Diversity.


Relationship to people

Along 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 ...
, the tricolored bat is one of two species of bat whose rabies variants are responsible for 70% of human rabies cases from bats in the US. Additionally, the rabies virus variants associated with these two species caused 75% of cryptic rabies deaths in the US (rabies cases where the exposure route is unclear, and no bite history exists). From 1958–2000, sixteen people in the US died from the rabies variant associated with tricolored bats, or 46% of all nationwide indigenous (not acquired elsewhere) rabies fatalities. The tricolored bat is infrequently encountered by humans and submitted for rabies testing, with only thirty-one individuals tested for rabies in the US in 2017. Of those, one (3.4%) tested positive for the virus.


See also

* Bats of Canada * Bats of the United States


References


External links

* * {{Authority control Vesper bats Bats of Canada Bats of the United States Bats of Mexico Bats of Central America Fauna of the Eastern United States Fauna of the Great Lakes region (North America) Mammals described in 1832 Taxa named by Frédéric Cuvier