Eastern pipistrelles are effective echolocators. Their echolocation calls are a combination of fundamental and second ary harmonics, which helps to distinguish their calls from those of similar species which share their geographic range. The use of harmonics allows eastern pipistrelles to increase their target resolution and aids in their ability to efficiently capture prey (MacDonald et. al., 1994).
The young are able to call to their mothers (Fugita and Kunz, 1984). These calls are a type of social call that signals female-infant interactions. These calls allow mutual recognition (Pfalzer and Kusch, 2003).
Although not specifically mentioned in any references, some communication must occur between a mother and her young through touch. Tactile communication may also occur between mates.
Communication Channels: tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; ultrasound ; echolocation ; chemical
This species is not considered threatened at the global or national levels, but it is a species of special concern in the state of Michigan.
Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%.
US Federal List: no special status
CITES: no special status
State of Michigan List: special concern
IUCN Red List of Threatened Species: least concern
Eastern pipistrelles sometimes inhabit human dwellings and may be considered un-welcomed guests.
Negative Impacts: household pest
Eastern pipistrelles eat many insects that may be harmful to humans.
Positive Impacts: controls pest population
Eastern pipistrelles are insectivores and help control the populations of the insects they consume.
Eastern pipistrelles are insectivores and are considered generalists. Stomach content and fecal analysis show that eastern pipistrelles consume a variety of insects including Coleoptera, Homoptera, Diptera, Hymenoptera, Lepidoptera, Neuroptera, Ephemoptera, Hemiptera, Psocoptera and Trichoptera. The diet of pipistrelles varies geographically (Griffith and Gates, 1985; Carter et al., 2003).
Because of their effective use of harmonics during echolocation, P. subflavus is an efficient hunter (MacDonald et al., 1994). Eastern pipistrelles are able to consume 25% (1.4 g to 1.7 g) of their body weight (5.3 g to 6.7 g) within half an hour (Gould, 1955).
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Eastern pipistrelles, Perimyotis subflavus are found throughout the eastern United States, and the far eastern edge of Mexico and Central America. These bats are found as far north as the southern edge of Canada and the southern edge of their range ends in northern Honduras (Fugita and Kunz, 1984).
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Eastern pipistrelles can be found in open woods near the edges of water, as well as over water. They are not usually found in open fields or deep forests (Schmidly, 1991; Nowak, 1991). They roost in rock crevices, caves, buildings, and tree foliage in the summer. During the winter, caves, mines, and deep crevices serve as hibernacula (Briggler and Prather, 2003; Sandel et al., 2001).
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Wetlands: marsh
Other Habitat Features: caves
Eastern pipistrelles have a lifespan of 4 to 8 years in the wild (Nowak, 1991). The known record for the oldest P. subflavus is 14.8 years.
Range lifespan
Status: wild: 14.8 (high) years.
Typical lifespan
Status: wild: 4 to 8 years.
Eastern pipistrelles are small bats with yellowish-brown pelage. The individual hairs of P. subflavus are tricolored; the base is dark, the middle is yellowish brown, and the tips are dark. This trait may be used to distinguish them from similar species such as Pipistrellus hesparus.
The tragus of P. subflavus is long, straight, and bluntly rounded. The calcar lacks a keel, the membrane is blackish, and the dorsal base of the interfemoral membrane is furred (Schmidly, 1991). Eastern pipistrelles have a dental formula of I 2/3, C 1/1, P 2/3, M 3/3 = 36 (Whitaker and Hamilton, 1998).
Eastern pipstrelles are sexually dimorphic: Females are larger than males. In the fall, the mean weights of females and males are 7.9 g and 7.5 g, respectively. In the spring, females average 5.8 g, and males average 4.6 g.
The measurements for P. subflavus are as follows: length 77 mm to 89 mm; tail 34 mm to 41 mm; hind foot 7.3 mm to 9.9 mm; ear 12.4 mm to 14.1mm; forearm 31.4 mm to 34.1 mm; and wingspan 220 mm to 250 mm (Fugita, and Kunz, 1984; Farney and Fleharty 1969).
Range mass: 4.6 to 7.9 g.
Range length: 77 to 89 mm.
Range wingspan: 220 to 250 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
At this time there is no information regarding the natural predators of P. subflavus. Eastern pipistrelles are often killed by humans. Generally, bats are most vulnerable to predators during the day, while they are in their roosts.
Known Predators:
Eastern pipistrelles copulate between August and October while “swarming” in front of cave openings. This is the only time the sexes of this species are together- during this time females mate with multiple males (Whitaker and Hamilton, 1998).
Mating System: polygynandrous (promiscuous)
After copulation, female eastern pipistrelles store sperm over hibernation until they ovulate in the spring. Insemination occurs in the spring with ovulation (Nowak, 1991). Up to seven ova may be fertilized, but only two will implant. This results in twins (Wimsatt, 1945). Newborn twins weigh up to 52% of the weight of the mother. It has been suggested that having twins is a response to the high mortality rate of the young, however having twins is rare among bats (Hill and Smith, 1984).
Gestation lasts 44 days from the time of implantation to parturition. Birth occurs from the end of May to early June depending on the latitude of the population (Whitaker, 1998). The young are altricial, however they are able to make a clicking sound to signal their mothers (Fujigta and Kunz, 1984).
Breeding interval: Eastern pipistrelles breed twice a year.
Breeding season: Copulation occurs between August and October and again in the spring.
Range number of offspring: 2 to 2.
Range gestation period: 44 (high) days.
Average gestation period: 44 days.
Range : 28 (high) days.
Average : 28 days.
Range time to independence: 5 (high) weeks.
Range age at sexual or reproductive maturity (female): 3 to 11 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; sperm-storing ; delayed fertilization
Average birth mass: 0.94 g.
Average number of offspring: 2.
Female P. subflavus carry their babies to different roosts. Males do not help rear the young (Whitaker, 1998). Within one week the young are covered in fur. At 3 weeks they are able to fly (Nowak, 1991). The young are weaned at 4 weeks and begin to forage with their mothers. At 5 weeks the young are independent (Whitaker, 1998). Juveniles reach sexual maturity within 3 to 11 months (Fujigta and Kunz, 1984).
Female eastern pipistrelles carry their babies to different roosts. Males do not help rear the young. Within one week the young are covered in fur. At 3 weeks they are able to fly. The young are weaned at 4 weeks and begin to forage with their mothers. At 5 weeks the young are independent from their mothers. Juveniles reach sexual maturity within 3 to 11 months.
Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The tricolored bat (Perimyotis subflavus) is a species of microbat native to eastern North America. Formerly known as the eastern pipistrelle, based on the incorrect belief that it was closely related to European Pipistrellus 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 4.6–7.9 g (0.16–0.28 oz). 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.[2] 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 tricolored bat is one of two bat species whose rabies variants have most frequently been implicated in human rabies deaths in the US, with sixteen deaths from 1958–2000.
The tricolored bat was described as a new species in 1832 by French zoologist Frédéric Cuvier, who placed it in the genus Vespertilio with a scientific name of Vespertilio subflavus. The holotype had been collected in the US state of Georgia by American naturalist John Eatton Le Conte.[3] In 1897, American zoologist Gerrit Smith Miller Jr. placed it in the genus Pipistrellus for the first time as a result of its physical similarities to other members of the genus.[4] Its common name was thus the "eastern pipistrelle".[5] 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: Perimyotis. The name "Perimyotis" means "around Myotis", alluding to its similarities with the genus.[6] 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. 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.[7] Usage of the scientific name Perimyotis subflavus is widely accepted as of 2019.[8][9][1] Its common name was changed from "eastern pipistrelle" to "tricolored bat" to reflect its revised classification.[5]
A 2010 study found that the sister taxon of the tricolored bat is the canyon bat, with the authors suggesting that these two genera form a tribe, 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).[10] The tribe was later described as Perimyotini.[11]
Its species name "subflavus" means "a little less than yellow", meaning yellowish or pale yellow.[12] Four subspecies are recognized:[8]
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.[12] It is the smallest bat species found in the eastern and midwestern US.[13] Individuals have a forearm length of 31.4–34.1 mm (1.24–1.34 in) and weigh 4.6–7.9 g (0.16–0.28 oz).[14] Its forearms are reddish, contrasting sharply with the black membranes of its wings.[15] Its wingspan is 21–26 cm (8.3–10.2 in).[16] It has a dental formula of 2.1.2.33.1.2.3 for a total of 34 teeth.[14]
The tricolored bat is a seasonal breeder, with copulation (mating) occurring in the fall before hibernation. Ovulation does not occur until the spring, however, and females store the males' sperm in their uteruses through the winter. Gestation (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.[14] The mother leaves the offspring behind at the roost while she forages at night.[16] Offspring develop rapidly, beginning to fly at three weeks old. By four weeks old, they are foraging for themselves.[14] Young do not reach sexual maturity in their first fall; they do not breed until their second fall.[16]
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.[14]
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.[16][17] Trees used for this purpose include oak, maple, the eastern cottonwood, and American tulip tree.[18] Males are solitary and do not form colonies.[17] In Nova Scotia, 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.[19]
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 from November to April. More bats used the mine as a roost in the winter than in the summer.[20] 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 2.65 g (0.093 oz), while females lose an average of 2.5 g (0.088 oz).[21]
The tricolored bat is insectivorous, consuming small prey of 4–10 mm (0.16–0.39 in) in length. Prey taxa include mosquitoes, beetles, ants, moths, and cicadas. It forages with slow, erratic flight in areas near water or forest edges.[14] It is one of the first bat species to begin foraging each night.[22] 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 kHz.[16]
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The tricolored bat's natural predators include the northern leopard frog, birds of prey, raccoons, snakes, skunks, and prairie voles.[12][14] Feral cats will also catch and kill them as they leave their hibernacula (cave or mine used for hibernation).[16] There are also records of it being attacked by the hoary bat.[14][23] The tricolored bat is the host to several species of endoparasites (internal parasites) and ectoparasites. Oocysts (spores) of an Eimeria species (Eimeria heidti ) have been recovered from its guano (feces).[24]
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.[25] 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.[26]
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.[17]
As of 2018, it is listed as a vulnerable species by the IUCN. In 2008, however, it was considered a least-concern species, 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.[1] Historically, it was one of the most common bat species of eastern North America.[22] 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.[27] In 2016, the Center for Biological Diversity and Defenders of Wildlife submitted a petition to the United States Fish and Wildlife Service (USFWS) to list the tricolored bat under the Endangered Species Act of 1973. The USFWS determined that the petition demonstrated that listing the species as "threatened" or "endangered" may be warranted.[28] In September 2022, the USFWS announced[29] it would protect the bat as endangered under the Endangered Species Act, following a lawsuit[30] from the Center for Biological Diversity.
Along with the silver-haired bat, 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.[31] 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).[31] 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.[31] 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.[32]
The tricolored bat (Perimyotis subflavus) is a species of microbat native to eastern North America. Formerly known as the eastern pipistrelle, based on the incorrect belief that it was closely related to European Pipistrellus 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 4.6–7.9 g (0.16–0.28 oz). 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 tricolored bat is one of two bat species whose rabies variants have most frequently been implicated in human rabies deaths in the US, with sixteen deaths from 1958–2000.
