Tricolored Bat

Perimyotis subflavus, formerly the eastern pipistrelle, is one of the smallest bats in eastern North America at 7–9 cm long, 21–26 cm wingspan and only 4–8 g. Its common name comes from individual hairs banded dark at the base, pale yellow in the middle and brown at the tip, combined with distinctive pinkish forearms contrasting with black wing membranes. Females bear twins in June. The species is highly susceptible to white-nose syndrome, which has caused declines exceeding 90% across much of its range, and it now carries elevated conservation status in many jurisdictions.

Emergence is early, and flight is weak, erratic and moth-like over waterways, woodland edges and roadways, feeding on small flies, beetles, leafhoppers and moths. Individuals hibernate singly rather than in clusters, choosing the most thermally stable and humid pockets of caves, mines and occasionally deep culverts and cellars, and often hang undisturbed long enough to accumulate condensation droplets on their fur. Because it roosts alone or in very small groups, it does not create the guano volume that drives most structural complaints; encounters are usually single bats in a garage, culvert or breezeway.