Eastern Red Bat (Lasiurus borealis)
- Protection Status Notes
- Red bats are thought to be one of the most abundant bats throughout their range, though they appear to have declined substantially since the 1800's. L. borealis is not listed by the U.S. Fish and Wildlife Service.
- Lasiurus borealis is a medium-sized bat with a reddish-orange coat. Adult males are brightly colored, in contrast to the more grayish females and juveniles. Either sex may have white tipped hairs, creating a frosty appearance. The underarms are fully furred to the wrists, as is the dorsal surface of the tail membrane. White patches of fur are present on the shoulders and wrists. The eastern red bat has a forearm of 37-45 mm in length and weighs 7-16 g. No external characteristics are known by which the eastern red bat can be identified with certainty from its western counterpart, L. blossevillii. However, their ranges are not believed to overlap except in extreme western Texas and southern New Mexico. The hoary bat is much larger than the eastern red bat, with a forearm greater than 50 mm. Yellow bats lack the distinctive white markings on shoulders and wrists.
- Life History
- Red bats typically live alone, or in family groups consisting of a mother and her young, except when they group together during migration, as they move to warmer regions to hibernate. Their breeding season is in fall, and females give birth in early summer. Litter size ranges from one to five pups, with an average of three. Young are born blind and well furred on their backs. Pups learn to fly in approximately one month and are weaned one to two weeks later.
Although some red bats in the South may remain in the same areas year-round, those in the northern U.S. and Canada, and most from the Plains States, are clearly migratory. In the fall, southward travel seems to be associated with the passage of cold fronts. The sexes are thought to migrate in separate groups and may actually travel with other bat species. Many red bats have been recorded migrating during the day from August to October. Some have even been noted flying over the Atlantic Ocean!
Red bats are often the first bats to emerge after sunset, typically flying high and eventually coming within 6.5 to 13.1 feet of the ground as darkness approaches. They have long narrow wings adapted for rapid, poorly maneuverable flight, yet are willing to land on light poles to catch moths, and may even catch some prey from the ground. They feed most actively during the first several hours after sundown, but nursing mothers may feed all night. These bats are thought to travel at least 2,000 to 3,300 feet from day roosts to feeding sites and may return to the same feeding grounds on consecutive nights. Red bats eat mostly moths and beetles, but also dine on planthoppers, leafhoppers, and spittlebugs. When possible, they actively select larger prey. On especially warm winter evenings, males emerge from hibernation in order to feed, sometimes even in mid-afternoon, though females apparently do not.
- Red bats forage in a variety of habitats, mostly over land, along the edges of pastures, crop lands, or other openings dotted with large deciduous trees. They also have been found in cypress stands, and near pecan trees along rivers. They prefer forested environments.
During winter, hibernating red bats have been documented in a variety of locations, ranging from tree hollows and exposed tree trunks to areas on the ground covered in leaf litter. During summer, they roost in foliage. Hanging by one foot, wrapped in their furry tail membranes, they are well concealed and resemble dead leaves. They roost in the same location for several weeks at a time.
- The Eastern Red Bat is found from the eastern edge of the Rocky Mountains across southern Canada to the Atlantic Coast and south through the United States to central Florida, western Texas, southern New Mexico and northern Mexico.
- Threats and Reasons for Decline
- Given recent discoveries of red bats hibernating in grass and leaf litter, it is likely that some die as a result of controlled burning in winter, especially in deciduous forests.
- Ongoing Recovery
- Based on knowledge of roosting and feeding behavior, the red bat ranks among a farmer's best friends. Where feasible, it would make sense to foster hedgerow roosting habitat along crop borders and to carefully consider how pesticides are used. Furthermore, forestry practices that employ controlled burning need to be planned to minimize mortality in areas where red bats are known to hibernate in leaf litter.
- Practically nothing is known about the status of this bat, since, like other foliage-roosting bats, it does not form large colonies that can be surveyed . However, monitoring select summer roosting areas has proven effective. Study of migratory flyways also could be enlightening. Based on highly credible observations of large flocks of red bats in their diurnal migrations from 1870's, it is thought that they may have declined far more than suspected over the past 100 years.
Refer to the online version of The Mammals of Texas for additional details on the Eastern Red Bat.