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New Jersey Endangered and Threatened Species Field Guide
Species Group: Mammal
State: Special Concern
Red bats are medium-sized, with a weight of 7 to 13 grams, a body length of about 3.5 to 4.5 inches, and a 13-inch wingspan. Their fur color ranges from yellowish-red to a deep orange-red, with female red bats tending to have a more frosted appearance and males being a darker hue. A distinctive feature of the red bat is its thickly furred tail-wing membrane, called the uropatagium. Red bats are capable of enduring temperatures of as low as 23 degrees Fahrenheit, in part because they can enclose themselves in this heavily furred membrane for insulation.
DISTRIBUTION AND HABITAT
Red bats can be found in forested habitats of the U.S. east of the Rocky Mountains, and just over the Canadian and Mexican borders. The most common of the eastern "tree bat" species, red bats roost alone in the open canopy of deciduous and coniferous trees, shrubs, and even vines, often dangling by a single foot to blend in with the foliage.
Red bats generally migrate south to warmer locations for the winter. They make the long-distance journey in large groups, often along the same Atlantic corridors as migratory songbirds. Although massive migrations have been documented, even in daytime, very little is known about the red bat’s winter locations or behavior. Some individuals do hibernate in New Jersey, using tree hollows or burrowing beneath the leaf litter on the forest floor. They may be seen out flying on warm winter afternoons, presumably in search of water or an insect meal.
Like other bats in our region, red bats are insectivorous. They consume mainly moths, beetles, ants, leaf-hoppers, and flies. Red bats are some of the earliest to emerge at dusk to begin their nightly foraging in clearings, along forest edges, or even at light sources for the moths they attract. The bats will strike at a group of insects using a signature steep-diving maneuver roughly every 30 seconds.
Like other insect-eating bats, red bats use echolocation to navigate and find their prey. These bats emit rapid high-frequency calls while searching. The echoes reveal the size, shape, distance, and trajectory of insects, enabling the bats to follow their movements and ultimately snatch their prey from the air. As they hone in, they increase their calls to up to 200 pulses per second in what is referred to as the "feeding buzz."
Like many other species, red bats mate during August and September as they congregate into migratory groups. Most have left their northern summer range by late October and will remain in the warmer southern regions until April. Red bats remain active if the climate permits. Those who remain at the northern limits of the migratory range hibernate in tree hollows or beneath the leaf litter during cold weather.
Females store sperm until the spring when they ovulate. They typically give birth to two or three young but can have as many as five at once, after about 80 to 90 days of gestation. These litter sizes are uncommon among bats, most of which have just one young per year. Female red bats have four mammary glands to accommodate nursing multiple pups, compared to the two mammary glands of most other bat species. The mothers nurse their young until they are capable of flight at around five weeks old. Males do not participate in pup rearing.
Known predators of the red bat include hawks, owls, blue jays, opossums, and other climbing animals. Red bats live up to 12 years.
CURRENT STATUS, THREATS, AND CONSERVATION
As solitary "tree bats" seldom encountered by people, red bats have evaded the persecutions sometimes faced by the bats who dwell in buildings or caves. Their preference for roosting in the open tree canopy also gives them a much wider range of options than bats which depend on dead/dying trees or other specific habitats. And since red bats do not typically hibernate below ground, they are not susceptible to the devastating effects of White-nose Syndrome.
However, red bats and other migratory species are taking massive hits from wind farms along their migration routes. Recent studies estimate that around 500,000 bats (mainly red bats, hoary bats, and silver-haired bats) may now be killed annually by wind turbines in the U.S. Researchers believe that bats are drawn to the turbines as places to perch, hunt for insects, or engage with mates, or simply for curiosity's sake. Bats are either struck by the fast-moving blades or killed by barotrauma - the damage to air-containing organs caused by rapid pressure change. A working group called the Bats and Wind Energy Cooperative (BWEC) was formed in 2003 to tackle this emerging issue. Solutions include seasonal adjustments to turbine cut-in speeds (wind speed at which the blades start spinning), acoustic and/or light deterrents, and avoiding turbine development in high-risk locations.
Red bats also appear to be vulnerable to vehicle strikes while foraging along roadways.
In 2013, the New Jersey Endangered and Nongame Advisory Committee recommended a Special Concern status for this species, but no formal rule proposal has been filed to date.
Learn about the work being done to research and protect NJ's bats at our Bat Project webpage.
Text written by Heather Kopsco and MacKenzie Hall in 2014.
Species: L. borealis
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