On September 13, 2022 the U.S. Fish and Wildlife Service announced a proposal to list the tricolored bat as endangered under the Endangered Species Act. The bat faces extinction due to the impacts of white-nose syndrome, a deadly disease affecting cave-dwelling bats across the continent.
The tricolored bat (Perimyotis subflavus) is one of the smallest bats native to North America. The once common species is wide ranging across the eastern and central United States and portions of southern Canada, Mexico and Central America. During the winter, tricolored bats are found in caves and mines, although in the southern United States, where caves are sparse, tricolored bats are often found roosting in road-associated culverts. During the spring, summer and fall, tricolored bats are found in forested habitats where they roost in trees, primarily among leaves. As its name suggests, the tricolored bat is distinguished by its unique tricolored fur that appears dark at the base, lighter in the middle and dark at the tip.
White-nose syndrome, a disease that impacts bats, is caused by a fungal pathogen. It has led to 90 to 100% declines in tricolored bat winter colony abundance at sites impacted by the disease. Since white-nose syndrome was first observed in New York in 2006, it has spread rapidly across the majority of the tricolored bat range.
During the spring, summer and fall - collectively referred to as the non-hibernating seasons - tricolored bats primarily roost among live and dead leaf clusters of live or recently dead deciduous hardwood trees. In the southern and northern portions of the range, tricolored bats will also roost in Spanish moss (Tillandsia usneoides) and Usnea trichodea lichen, respectively. In addition, tricolored bats have been observed roosting during summer among pine needles, eastern red cedar (Juniperus virginiana), within artificial roosts like barns, beneath porch roofs, bridges, concrete bunkers, and rarely within caves. Female tricolored bats exhibit high site fidelity, returning year after year to the same summer roosting locations. Female tricolored bats form maternity colonies and switch roost trees regularly. Males roost singly.
During the winter, tricolored bats hibernate - which means that they reduce their metabolic rates, body temperatures and heart rate - in caves and mines; although, in the southern United States, where caves are sparse, tricolored bats often hibernate in road-associated culverts, as well as sometimes in tree cavities and abandoned water wells. Tricolored bats exhibit high site fidelity with many individuals returning year after year to the same hibernaculum.
A dense growth of trees and underbrush covering a large tract.
Tricolored bats are opportunistic feeders and consume small insects including caddisflies, moths, beetles, wasps, flying ants and flies.
Tricolored bats emerge early in the evening and forage at treetop level or above, but may forage closer to ground later in the evening. This species of bat exhibits slow, erratic, fluttery flight, while foraging and are known to forage most commonly over waterways and forest edges.
Average body length: 3 to 3.5 in (77 to 89 mm)
Tail length: 1.3 to 1.6 in (34 and 41 mm)
Forearm length: 1.2 to 1.3 in (31.4 to 34.1 mm)
Adult males average 0.26 oz (7.5 g) in September; 0.16 oz (4.6 g) in April
Adult females average 0.28 oz (7.9 g) in September; 0.20 oz (5.8 g) in April
The tricolored bat is distinguished by its unique tricolored fur that appears dark at the base, lighter in the middle and dark at the tip. Tricolored bats often appear yellowish, varying from pale yellow to nearly orange, but may also appear silvery-gray, chocolate brown or black. Newly flying young are much darker and grayer than adults.
Tricolored bats mate in the fall, hibernate in the winter and emerge in the spring. They then migrate to summer habitat where females form maternity colonies, where young are born. Bats disperse once young can fly, and then return to winter habitats to swarm, mate and hibernate. Tricolored bats exhibit site fidelity to both winter and summer roost habitat.
The oldest tricolored bat on record is a male captured 14.8 years, after it was originally captured and banded.
Male and female tricolored bats converge at cave and mine entrances between mid-August and mid-October to swarm and mate. Adult females store sperm in their uterus during the winter and fertilization occurs soon after spring emergence from hibernation. Females typically give birth to two young, rarely one or three between May and July. Young grow rapidly and begin to fly at 3 weeks of age and achieve adult-like flight and foraging ability at 4 weeks. Adults often abandon maternity roosts soon after weaning, but young remain longer. Tricolored bats are considered juveniles, called subadults, when entering their first hibernation and most probably do not mate their first fall.
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