Hoary Bat (Lasiurus cinereus)
- Protection Status Notes
- Nothing is known about the hoary bat's status or population trends. The mainland L. cinereus is not listed by the U.S. Fish and Wildlife Service, but the Hawaiian subspecies is listed as endangered.
- Lasiurus cinereus is a large and distinctively marked bat with long narrow wings. Its fur is long and soft, dark brown to black at the base, followed by a broad band of cream color, then a slightly narrower band of mahogany brown, tipped with white. The outer three colors are visible from the surface, giving the fur a hoary appearance. The bat has a distinctive yellowish-brown collar under its chin and yellowish ears edged in black. Dense fur extends to the tip of its tail and just beyond the wrists along the undersides of its wings, with distinctive white patches on the shoulders and wrists. Its forearm measures 50-57 mm and this bat weighs 20-38 g. It can be distinguished from all others by its coloration and size.
- Life History
- The Hoary Bat is solitary, usually living alone or in family groups, consisting of a mother and her young, except during migration. Males and females apparently come together only to mate in the fall. Females typically give birth between mid-May and late June and the vast majority have twins, but can have litters of one to four pups. At birth, young are covered with fine, silvery-gray fur on the head, shoulders, tail membrane, and feet. Their eyes and ears open in three days, and by the seventh day they begin to hang alone away from their mother for short periods of time. They learn to fly in about 33 days. Based on litter size, these bats are assumed to be relatively short-lived, most probably living no more than 6 or 7 years.
Hoary bats usually leave their roosts soon after dusk, having two foraging bouts, one in early evening and another an hour before sunrise. They often rely on speed and long-distance detection to hunt relatively large insects in open areas in meadows, over streams and rivers, or above stands of trees at canopy level. They prefer moths and beetles, but are also known to consume mosquitoes during periods of high abundance. Hoary bats are highly territorial, choosing feeding sites which they return to night after night.
In the fall, hundreds of Hoary Bats may travel together during fall migration. In the United States, most apparently overwinter in coastal areas.
Hoary Bats are rarely seen during winter hibernation. Spring migration appears to be slower and quite predictable, with pregnant females preceding males in their northward journey to their summer territories.
- The hoary bat lives in forests of the eastern U.S. and in arid deserts of the Southwest, but is most abundant in the forests and croplands of the Plains states and in forests of the Pacific Northwest. Diverse forest habitats with a mixture of forest and small open areas that provide edges seem ideal for this species.
They have been found in Spanish moss, squirrel nests, woodpecker holes, and out in the open on the trunks of trees, relying on their fur coloration to provide nearly perfect camouflage. During summer, they prefer tree roosts that are in edge habitats close to feeding grounds. Most females have been found rearing young in deciduous trees, while males seem more likely to also roost in conifers. Both tend to prefer older trees which apparently provide greater safety, and which they use for up to 5 weeks. Most roosts are 11.5 to 40 feet above the ground, some up to 65 feet, with mothers and young usually roosting higher than solitary adults. Hoary and red bats sometimes use the same roosts on different days and prefer nearly identical roosts for rearing young. Their roosting preferences include: 1) dense vegetation above; 2) unobstructed space below, allowing bats to drop to gain flight; 3) no potential perches beneath, which could aid detection by birds or other animals; 4) dark-colored ground cover, minimizing reflected sunlight; 5) sufficient surrounding vegetation to protect from wind and enhance heat and humidity retention; and 6) southern exposure, where vegetation is the most dense and heat gain the greatest.
- The hoary bat occupies the widest range and variety of habitats of any New World bat, living from Argentina and Chile northward through Canada. Stray migrants have been found in Bermuda, Iceland, and the Orkney Islands off Scotland. It lives in pine-hardwood forests of the eastern U.S. and in arid deserts and ponderosa pine forests of the Southwest, but is most abundant in mixed deciduous forests and croplands of the Plains States and in coniferous forests of the Pacific Northwest. This species is relatively uncommon in the northern Rockies and in the eastern U.S. A separate population, L. c. semotus, is found in the Hawaiian islands.
From August through October, hundreds of hoary bats may travel together during fall migration. In the United States, most apparently overwinter in coastal areas, along the West Coast from San Francisco south, and along the East Coast from South Carolina to central Florida, as well as in all of the Gulf States, west through Texas, and south through northern Mexico.
The hoary bat is a migratory species found statewide in Texas.
- Threats and Reasons for Decline
- Hoary bats are susceptible to loss of suitable roosting and foraging habitat when diverse forests are replaced by fewer tree species of less diverse ages.
Birds and snakes are their most likely predators.
- Ongoing Recovery
- More information on winter needs should be gathered to ensure year-round safety.
- More information is needed on population trends and on hibernation requirements.
Refer to the online version of The Mammals of Texas for additional details on the Hoary Bat.