New York Natural Heritage Program
Eastern Red Bat
Lasiurus borealis (Muller, 1776)

General Description [-]
Eastern red bats have red pelage that may appear brick to rusty red or buffy orange and is dense and wooly (Saunders 1988). The hair of the back and chest are tipped in white and they have a white shoulder patch. They have long, pointed wings and a long tail (Shump and Shump 1982). The bald parts of the tail and wing membranes are brownish black. Males tend to be more brightly colored than females and females are larger than males. Adults weigh 7-15 g (Shump and Shump 1982; Saunders 1988).

Identifying Characteristics [-]
Eastern red bats can be distinguished from other New York species by their red fur. In flight, they can be distinguished by the position of their tail, which is extended straight out from the body (Shump and Shump 1982). They have a swift direct flight similar to hoary bats but they are much smaller.

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

Behavior [-]
Eastern red bats roost hanging upside down from one or both feet, and they often resemble a dead leaf hidden in tree foliage (Saunders 1988). Eastern red bats are solitary but may forage or migrate with other individuals (LaVal and LaVal 1979; Saunders 1988). Average home range sizes of 68 and 94 hectares have been reported (Elmore et al. 2005; Walters et al. 2007).

Pairs copulate while in the air and sometimes flutter to the ground (Saunders 1988). In some parts of their range, red bats swarm near cave entrances to mate, although they do not use the cave for winter shelters (Saunders 1988). Young are born in late June or July and there is some variation in the number of offspring produced ranging between 1 and 5, and averaging 2.3 (Hamilton and Stalling 1972; Mumford 1973; Shump and Shump 1982; Saunders 1988).

Red bats emerge from their roosts from 1-2 hours after sunset, which is later than for many species, but before hoary bats (Shump and Shump 1982). They exhibit a swift direct flight, although they may behave more erratically during foraging. They forage at multiple heights including high over forests and fields, and between the ground and canopy (Barbour and Davis 1969; Saunders 1988). They return to certain areas to forage nightly, typically within 300m of their day roosts (Saunders 1988). They are most active foraging during the few hours following sunset and before dawn (Shump and Shump 1982; Saunders 1988).

There is evidence to support the use of chemical signals to communicate in this species, such as the use of the same perch by different individuals in successive nights during migration (Saunders 1988). Eastern red bats are migratory and may typically move to southern states to overwinter where they probably hibernate in trees (Barbour and Davis 1969; Shump and Shump 1982).

Diet [-]
A high percentage of the diet of the eastern red bat consists of beetles and moths with some regional differences in the variety of prey consumed. There are no known studies of diet in New York, however, there are several from the eastern United States. In South Carolina, eastern red bats consumed mostly beetles (Coleoptera) in early to mid summer but switched to a higher composition of moths (Lepidoptera) as beetle availability decreased in late summer (Carter et al. 2004). In West Virginia, eastern red bats preyed heavily on Lepidoptera which made up 47% of their diet followed by Coleoptera (25%), Tricoptera (10%), Homoptera (9%), and lesser amounts of Hemiptera, Diptera, and Hymenoptera (Carter et al. 2003). In southern Illinois, eastern red bats consumed primarily Lepidoptera (39%) followed by Homoptera (27%) and Coleoptera (23%), with lesser amounts of Diptera, Hemiptera, Hymenoptera, and Tricoptera (Feldhamer et al. 2009).
The Best Time to See
The best time to see eastern red bats in New York is in late May through July in the early evening.  See Identification Characteristics for tips on distinguishing this species in flight.
Present Reproducing
The time of year you would expect to find Eastern Red Bat present (blue shading) and reproducing (orange shading) in New York.