Tricolored Bat: Perimyotis Ubflavus

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Image of tricolored bat found in the wild

One of North America’s smallest bats is a tricolored bat, formerly known as the eastern pipistrelle. These bats have a solid yellowish-brown coat, but their name may seem misleading. Each individual hair is “tricolored” with a brown tip, a yellow center, and a dark base.

In most of eastern North America and the midwestern United States, the tricolored bat appears. Tricolored bats are a hibernating species and have in their range the longest hibernation time of any bat species. Tricolored bats can be seen in their habitats roosting and foraging when not hunkering down for the winter. ¹

Learn More: Bats Native To The United States

Tricolored Bat Body

The tricolored bat is small, weighing 0.2 to 0.3 ounces, and has an 8 to 10-inch wingspan. The expression “Tricolored” refers to the bat’s dark coat at the base of the body, yellowish-brown at the center, and dark at the tips.

The wing membranes are blackish, but there is a pinkish color on the face and ears. The pink color of the species is an apparent identifying feature of this species. Compared to its body size, this bat’s claws are large, allowing for easy ability to roost and catch prey. ²

Dimensions Of The Tricolored Bat

Wingspan: 8-10 in. (21-26 cm)
Weight: 1/5 of an ounce (6 g)
Body length: 2 3/4 – 3 3/4 in. (71-95 mm)
Forearm: 1 1/4 – 1 3/8 in. (33-36 mm)

Behavior Of The Tricolored Bat

Photo of tricolored bat in hibernation

The Tricolored Bat, typically in September or October, is one of the first bats to enter hibernation and typically is one of the last bat species to emerge in the spring.

During the first or second hibernation periods (end of the fall season), the highest mortality appears to occur, usually because of the failure to store large enough fat reserves for the early winter.

Tricolor bats carry out short annual migrations periods between winter hibernation and summer nursery sites. It is not known that such a journey exceeds 50 miles and averages 31 miles or less. These bats often swarm before entering hibernation at entrances to the cave or mine.

One of the first species to emerge every evening is the tricolored bat, usually having two foraging bouts per night, one starting shortly after sunset and another around midnight. While foraging, this bat has an erratic, fluttery flight pattern, and in the open, can achieve a flying speed of 11.6 miles per hour. Every two seconds, the tricolor bat can catch prey at the rate of one insect, increasing its body mass by as much as 25 percent in just thirty minutes. ³

Tricolored Bat Reproduction Cycle

Mating occurs before hibernation in the autumn and again in the spring in some cases. Females store sperm over winter and ovulate in April or early May when they become active. They give birth from late May to mid-July, usually to twins, after a 44-day gestation period. Each pup weighs about 1.6 g (both pups together weigh almost 50 percent of the mother’s after-birth body weight).

Born blind and hairless, pups can fly in about three weeks and are fully weaned by the fourth week. Tricolored bats live in the wild for up to 14 years.

Diet Of The Tricolored Bat

Since they are a smaller species, tricolored bats rely on small prey for the majority of their diet. Tiny insects, especially flies, moths, wasps, leafhoppers, and beetles (many of which are aquatic forms), are easy prey for this small bat.

With other feeding periods towards midnight and near daylight, they begin feeding around sundown. They generally forge at the edge of the forest over bodies of water. ⁴

Tricolored Bat Habitat

This species is found hibernating in the same places as large populations of other bats, such as small brown bats and northern myotis.

Tricolored bats tend to occupy the deeper portions of hibernaculum areas (deep areas within caves) where temperatures and humidity are higher. Tricolored bats usually roost alone in the summer, often in trees, but some males and non-reproductive females roost in hibernaculum areas in winter. Maternity colonies have been found in trees, rock crevices, and barns/other buildings. ⁵

Threats To The Tricolored Bat

Tricolored bats are most vulnerable to predation while roosting by animals such as raccoons, opossums, and snakes and can be taken while in flight by hawks and owls. General habitat loss and hibernation site disturbance are challenges for tricolored bats and other species in the northeast.

Tricolored Bat Common Predators

Skunks
Feral Cats
Prairie Voles
Snakes
Birds Of Prey
Northern Leopard Frog
Raccoons

Disease Affecting The Tricolored Bat Species

Tricolored bats, like other temperate cave-hibernating bats, are vulnerable to the White-nose Syndrome fungal disease. A fungus that grows incredibly well in the cold, moist environments of caves and mines, where it invades hibernating bats’ tissues during winter, causes the White-nose Syndrome.

The infection causes deterioration of the wing, loss of water, and excitement that costs bats their critical reserves of energy. In infected caves and mines, the mortality rate for tricolor bats appears to exceed 90 percent. White-nose Syndrome has spread to 25 U.S. states as of spring 2014. ⁶

Sources:

Texas Parks And Wildlife. “Tricolored Bat (Perimyotis Subflavus).” Texas Parks And Wildlife, Texas Government, tpwd.texas.gov/huntwild/wild/species/easpip. Accessed 8 Dec. 2020.
Center For Biological Diversity. “Tricolored Bat.” Biological Diversity, www.biologicaldiversity.org/species/mammals/tricolored_bat/index.html. Accessed 8 Dec. 2020.
“Conserving South Carolina’s At-Risk Species.” U.S. Fish And Wildlife Service, Feb. 2019, www.fws.gov/southeast/pdf/fact-sheet/tri-colored-bat.pdf.
Texas Parks And Wildlife. “Tricolored Bat (Perimyotis Subflavus).” Texas Parks And Wildlife, Texas Government, tpwd.texas.gov/huntwild/wild/species/easpip. Accessed 8 Dec. 2020.
“Attention Required! | Cloudflare.” Minnesota Department Of Natural Resources, www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AMACC03020. Accessed 8 Dec. 2020.
“Wildlife Field Guide for New Jersey’s Endangered and Threatened Species – Conserve Wildlife Foundation of New Jersey.” Conserve Wildlife Foundation Of New Jersey, www.conservewildlifenj.org/species/fieldguide/view/Perimyotis%20subflavus/#:%7E:text=Tricolored%20bats%20are%20most%20vulnerable,well%20as%20other%20northeast%20species. Accessed 8 Dec. 2020.