New York Natural Heritage Program
Tri-colored Bat
Perimyotis subflavus (Menu, 1984)

General Description [-]
The tri-colored bat is a medium-sized bat with tri-colored pelage on its back that ranges from dark grey at the base, to yellowish in the middle, and brown at the tip. They weigh 3.5-8 g (0.1-0.3 oz) and have a wingspan of 21-26 cm (8-10 in).

Identifying Characteristics [-]
Tri-colored bats are best identified by their uniquely tri-colored, yellowish fur which is dark at the base and tip and light in the middle. Tri-colored bats may also be identified by their weak flight which is described as moth-like.

Best Life Stage for Proper Identification [-]
Adults may be easiest to identify.

Behavior [-]
Tri-colored bats are nocturnal with periods of heightened activity at pre-dawn and dusk. They may range 5 miles from a roost to forage (MA Natural Heritage Program 2012).

Tri-colored bats are short-distance migrants traveling between winter hibernacula and summer habitat. The farthest known record was 52.8 km (Griffin 1940), although migration distances from hibernacula have not been extensively researched. Tri-colored bats may enter the hibernacula earlier in the fall and leave later in the spring compared to other species (Fujita and Kunz 1984).

Tri-colored bats breed in the fall and may breed again in the spring, coinciding with ovulation (Fujita and Kunz 1984). They swarm and mate near the cave entrance. Females store sperm over the winter until ovulation occurs in the spring, which coincides with emergence from winter hibernacula. Females generally give birth to two young.

Tri-colored bats often obtain insect prey by catching them in their tail and wing membranes. They may forage at varying heights, including within the canopy or above or below it (Menzel et al. 2005). They may forage in habitats such as woods, along waterways, or forest edges (Fujita and Kunz 1984).

Tri-colored bats are usually solitary but may be found roosting in small colonies; especially females which form maternity colonies in summer.

Diet [-]
Tri-colored bats consume a diverse diet with several studies reporting that Diptera (flies) (Ross 1967; Whitaker 1972; Carter et al. 2003) and other soft-bodied prey (Carter et al. 2003) are an important component. One study in Indiana, found that tri-colored bats consumed primarily homopterans (cicadellids) and beetles with a smaller component of lepidopterans (Whitaker 2004). A study in Illinois found more than half their diet consisted of Trichopterans (caddisflies) followed by beetles and ants (Feldhamer et al. 2009). In West Virginia tri-colored bats consumed a wide mix of prey including Diptera, Hymenoptera, Tricoptera, Lepidoptera, and Homoptera (Carter et al. 2003). There are no known studies of the diet of this species from New York.
The Best Time to See
Tri-colored bats may best be seen shortly after sunset or in the early morning before dawn in the late spring and summer. They are one of the first bats to emerge to forage in the evenings (Hamilton 1943). They have a slow, erratic flight pattern that may be distinguished from other species by an experienced observer.
Present Active Reproducing
The time of year you would expect to find Tri-colored Bat present (blue shading), active (green shading) and reproducing (orange shading) in New York.