There are three subspecies of Lasiurus cinereus: L. c. cinereus in North and Central America, L. c. semotus in Hawaii, and L. c. villosissimus in South America.
Like all microbats, hoary bats use echolocation while flying. They make a shrill, hissing sound when disturbed. Lasiurus cinereus is one of the only vespertilionid bats which makes an audible chatter during flight.
Perception Channels: tactile ; acoustic ; echolocation ; chemical
Hoary bats are widespread and secure over much of their range. One subspecies, the Hawaiian hoary bat (Lasiurus cinereus semotus), is listed as endangered by the U.S. Fish and Wildlife Service.
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%. While there are currently no reports of Lasiurus cinereus mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Hoary bats occasionally hang out under overhangs of houses and garages, but this is only menacing and they rarely cause any true disturbance to homeowners.
These bats have a relatively high incidence of rabies. In some years, 25% of sick bats collected were found to be rabid.
Negative Impacts: injures humans (carries human disease)
Hoary bats prey on many insect species that are considered to be pests.
Positive Impacts: controls pest population
Hoary bats have an important ecosystem role as insect consumers. These bats are often infested with mites (Pteracarus chalinolbus and Chiroptonysus americanus), helminths (Longibucca lasiura, Oochoustica taborensis, and Physocephalus), and protozoa (Distoma).
Commensal/Parasitic Species:
Moths (Lepidoptera) make up the bulk of the diet of hoary bats. These bats are also known to feed on flies (Diptera), beetles (Coleoptera), small wasps and their relatives (Hymenoptera), grasshoppers (Orthoptera), termites (Isoptera), and dragonflies (Odonata). The bat approaches the insect from behind, taking the abdomen and thorax in its mouth and biting off and swallowing this area of the insect, while dropping the wings and head. In comparison to other bats, hoary bats feed on relatively few orders of insects. On rare occasions, these bats have been observed to feed on leaves, grass, shed snake skin, and eastern pipistrelles.
Animal Foods: mammals; insects
Plant Foods: leaves
Primary Diet: carnivore (Insectivore )
Hoary bats are the most widespread of all bats in the United States. Though not yet recorded in Alaska, these bats are thought to occur in all 50 states. They range from the tree limit in Canada down to at least Guatemala in Central America, and throughout South America. They are the only bats found in Hawaii. There are records of migrant hoary bats on Southampton Island off of Northern Canada, and from Iceland, Bermuda, and the Orkney Islands off Scotland. They are rare in most of the eastern United States and northern Rockies and common in the Pacific Northwest and prairie states. They are abundant in California, Arizona, and New Mexico, where they winter. They winter in southern California, southeastern United States, Mexico, and Guatemala, but have also been found in Michigan, New York and Connecticut during December and in Indiana during January. This suggests that some may winter farther north than was previously expected.
Sexes are generally only found together in parts of Nebraska, Montana, and the Badlands of South Dakota. Males and females are usually separated during the warmer months in North America, except during the mating season. Females appear to be more concentrated in the western part of North America. There is evidence for an altitudinal separation of sexes in California, with females concentrated in the lowlands and coastal valleys and males higher up in the foothills and mountains.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Authorities disagree as to the bat's preference for coniferous versus broadleaf trees. Hoary bats are thought to prefer trees at the edge of clearings, but have been found in trees in heavy forests, open wooded glades, and shade trees along urban streets and in city parks.
Habitat Regions: temperate ; tropical
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; rainforest ; scrub forest
Other Habitat Features: urban ; suburban
Average lifespan
Sex: male
Status: wild: 2.1 years.
The body of hoary bats is about the size of a fat mouse. Hoary bats weigh 20 to 35 g. The length from the tip of the nose to the end of the tail vertebrae is 13 to 15 cm. The wingspan is 43 cm. These bats have blunt, rounded noses and small, beady eyes. The ears are short, thick, broad, and rounded. When laid forward they do not reach the nostrils. The tragus in the ear is short and blunt. The hindfoot is half as long as the tibia and has thick fur on the dorsal side. The thumbs are long. The calcar is twice as long as the hindfoot and is narrowly keeled on the posterior edge, bearing lobes on the tip. These bats have four mammary glands.
Thick, long, soft hair covers the entire dorsal surface extending to the elbow, the median ventral border of the undersides of the wings, the ventral side of the long bones that make up the upper arm and forearm, and the basal part of the lower surface of the interfemoral tail membrane. The coloring of the dorsal area (including the tail membrane) is a mixed brown-gray with a heavy white tinge, giving these bats a frosty appearance. In fact, these bats' name means "frosty or ash colored hairy tail." The individual silky hairs are basally dark, medially yellowish, and distally black with white tips. The belly of these bats is not heavily frosted. The throat has a distinct yellow patch. The hair on the elbow, at the base of the clawed thumb, and the upper arm is yellowish as well. The ears are yellow with black edges. Brownish fur extends out on the underside of the wing nearly to the wrist.
The skull is large (16 mm long) and broad (13 mm wide), with a large auditory bullae. These bats have large, strong teeth, with the first premolar located at the inner junction of the large canine.
Juveniles appear nearly grayish, but still have a frosty appearance.
Range mass: 20 to 35 g.
Range length: 13 to 15 cm.
Average wingspan: 43 cm.
Average basal metabolic rate: 1.19 cm3.O2/g/hr.
Other Physical Features: endothermic ; bilateral symmetry
The main enemies of hoary bats are hawks and owls. American kestrels and rat snakes have on rare occasions been reported to feed on hoary bats. These bats are also known to become entangled in barbed wire fences. Another important source of mortality is females falling out of their roost with attached young, thus becoming easy prey for terrestrial passers by.
Known Predators:
In North America, the breeding range of hoary bats extends across Canada and northcentral and northeastern United States down to at least Kansas and Kentucky, and perhaps to Arkansas, Louisiana, and Georgia. Hoary bats are thought to mate around the time of autumn migration. Researchers are uncertain about whether copulation occurs before, during, or after the southward migration. Courtship is believed to proceed during day flights. Mating may also occur at southern wintering grounds.
Copulation is followed by delayed fertilization, a process in which the sperm is stored in the female reproductive tract all winter and is available to fertilize the egg when ovulation takes place in the spring. Parturition appears to range from the middle of May into early July. Little is known about the bat's gestation time. One study found three females to deliver between 900 and 1300 hours. Litter size is usually two, but can range from one to four.
Breeding interval: Hoary bats breed once per year.
Breeding season: Hoary bats breed in the autumn.
Range number of offspring: 1 to 4.
Average number of offspring: 2.
Average gestation period: 56 days.
Average weaning age: 34 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; sperm-storing ; delayed fertilization
Average birth mass: 5.5 g.
Average gestation period: 56 days.
Average number of offspring: 2.
Hoary bats give birth to their young while hanging upside down in the leafy shelter of their daytime retreat. The newborn's skin is brown, darker on the body than on the wings, and lighter beneath. The throat and head are much paler and their feet are nearly black. Fine, silver-gray hair covers their dorsal area. The hoary bat's ears and eyes are closed at birth and open on days three and twelve, respectively. Purposeful flight is possible for the infants by the thirty third day. The young cling to the mother in the day, while she sleeps, and hang on a twig or leaf while she hunts at night.
Parental Investment: altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The hoary bat (Lasiurus cinereus)[2] is a species of bat in the vesper bat family, Vespertilionidae. It lives throughout most of North America (and possibly also in Hawaii, although this is disputed).
The hoary bat was described as a new species in 1796 by Palisot de Beauvois. Beauvois noted that the holotype was collected in the US state of Pennsylvania by an individual identified as "Master Pancake".[3] It has many taxonomic synonyms, including Vespertilio pruinosis (Say, 1823) and Atalpha mexicana (Saussure, 1861). Mammalogist Harrison Allen was the first to use its current name combination of Lasiurus cinereus, doing so in 1864.[4] In a later publication, Allen placed it in the now-defunct genus Atalapha, with a scientific name of Atalpha cinerea.[5]
The South American hoary bat (L. villosissimus), which is found throughout South America, and the Hawaiian hoary bat (L. semotus), which is endemic to Hawaii, were both previously classified under the hoary bat, but phylogenetic evidence supports them being distinct species.[6]
Some have argued to elevate the subgenus (Aeorestes) to a genus level classification for L. cinereus. However, this has not been accepted by taxonomic authorities as it violates the International Code of Zoologigal Nomenclature[7][8]
It ranges throughout North America, from northern Canada south to Guatemala. Although the Hawaiian subspecies L. semotus was reclassified into a distinct species, studies in 2015 and 2017 found evidence supporting two different colonization events of Hawaii by Lasiurus species; one about 1.4 million years ago by the ancestors of L. semotus, but also a much more recent colonization by true L. cinereus. This would mean that L. cinereus also inhabits the Hawaiian islands, in cryptic sympatry with L. semotus.[6][9] However, in contrast, a 2020 genetic study found no evidence of multiple bat species on Hawaii, finding the islands to only be inhabited by a single species, L. semotus, and attributed the previous results as a consequence of incomplete lineage sorting.[10]
The hoary bat averages 13 to 14.5 cm (5.1 to 5.7 in) long with a 40 cm (15.5 in) wingspan and a weight of 26 g (0.92 oz). It is the largest bat normally found in Canada. Its coat is dense and dark brown, with white tips to the hairs that give the species its 'hoary' appearance for which it is named.[11] The body is covered in fur except for the undersides of the wings. Males and females are dimorphic in body mass, with females 40% heavier than males.[12]
The bat normally roosts alone on trees, hidden in the foliage, but on occasion has been seen in caves with other bats. It prefers woodland, mainly coniferous forests, but hunts over open areas or lakes. It hunts alone and its main food source is moths. The bats can cover an impressive 39 km (24 mi) while foraging.[11] Hoary bats are long-distance migrants, spending the winter in Central America and the southwestern United States and the spring and summer in more northern latitudes in the United States and Canada.[13]
The reproductive cycle of the hoary bat is not yet fully documented, but it is thought that they mate in August with birth occurring in June of the following year. It is thought that the gestation period is only 40 days and that mammalian embryonic diapause (delayed implantation) may play a role. Females typically bear twins, though litter sizes range from 1–4.[14] Young are typically weaned after 7 weeks.[15]
While not listed as threatened or endangered, hoary bats suffer significant mortality from wind turbines. Across the United States in 2005, 40% of all bats killed by wind turbines were hoary bats—over 1000 hoary bats were killed in 2005.[16] Most bat deaths occur during migration in the spring and fall.[17] One common theory explaining this is that bats are attracted to the tall structure, possibly believing them to be trees that can be used for rest.[18]
The hoary bat (Lasiurus cinereus) is a species of bat in the vesper bat family, Vespertilionidae. It lives throughout most of North America (and possibly also in Hawaii, although this is disputed).
