Art Credit: Sahina Irvin
Appearance
Photo courtesy of C. Burney
Eastern red bats are named for the brick-red fur covering their bodies. Males are usually a darker red color, while females tend to have a frosted tint to their fur (Whitaker and Hamilton 1998). Their wrists and shoulders sometimes have patches of white, and the belly hair is usually lighter. The entire body is covered in thick fur, including the uropatagium, which is the skin membrane that stretches between the bat’s hind legs (Whitaker and Hamilton 1998). Eastern red bats have small ears, and the small piece of skin in front of the ear canal, called the tragus, is triangular shaped and blunt (Shump and Shump 1982). They typically weigh a quarter to a half ounce (7-14g), about the same as a half dollar coin, and measure 4-4.5 inches (10-12cm) from head to tail. The long, broad shape of their wings allows them to be fast and moderately maneuverable flyers (Shump and Shump 1982).
Behavior
Like all Florida bats, eastern red bats are insectivores, meaning they mainly eat insects. Although they prefer moths (Newbern et al. 2019), they will also eat flies, beetles, and cicadas. They eat many crop pests (Clare et al., 2009), including a major moth pest of pecans (Braun de Torrez et al., 2019). Eastern red bats catch their prey in flight, using a technique called “aerial hawking” (Arrayo 2016). They leave their roost at dusk each night and hunt for approximately 2 hours, often in areas with an open tree canopy (Elmore et al. 2005). With increasing human development, eastern red bats can also be seen hunting within 500m of a light source where large groups of insects are found (Hickey et al. 1990, Hickey et al. 1996). Like most bats, eastern red bats use echolocation to find prey and communicate with other bats. By frequently emitting high-pitched calls and listening to the echo, they can home in on an insect’s exact location as they fly by (Simmons et al. 1996).
While the mating behaviors of eastern red bats are not well known in Florida, they have been studied elsewhere in their range. They typically mate in flight between Autumn and September. Like many bat species, they then delay fertilization until the early to late spring (Arrayo 2016). Females give birth to between 1 and 4 pups in early-mid Summer, with twins being the most common. After about five weeks, the pups are weaned and learn to fly, though they stay with their mother for some time before roosting on their own (Arrayo 2016). The gestation period is estimated to be 84 days and red bats typically live about two years in the wild (Kurta 2017).
Habitat
The eastern red bat likes to roost in areas with thick vegetation and few people (Arrayo 2016). They tend to live in forests, forest edges, and along hedgerows, mostly roosting in deciduous trees but also sometimes in coniferous trees. Their red fur acts as camouflage in certain tree types such as sycamore, elm, and oak (Constantine 1996) and lets them resemble dead leaves or pinecones. They prefer to hibernate in hollow trees from mid-April to late October (Arrayo 2016), and usually roost on their own or in small family groups. Eastern red bats are common across the Eastern United States and occur across northern Florida, often migrating down from northern states for the winter. It is currently unclear how far south they range in Florida. As human development increases, the species has been observed to roost closer to urban areas (NYNHP).
Threats
While they can tolerate some levels of disturbance, continued deforestation remains a major threat to the eastern red bat (Arrayo 2016). Because they roost in trees, these bats rely heavily on dense patches of forest which are at risk from increasing levels of human development.
Wind turbines are also a major threat to eastern red bats. Turbines cause over 150,000 fatalities each year among bats in the U.S. (Zimmerling and Francis 2016), with eastern red bats having the second most fatalities of any bat species (Kunz et al. 2007). Because they migrate long distances each year, they encounter wind turbine fields more frequently than other species. As tree bats, they also may be attracted to the tall structures (Jameson and Willis 2014, Zimmerling and Francis 2016).
Although eastern red bats have been found carrying the spores of the fungus that causes white-nose syndrome (Pseudogynmoascus destructans), no individual has ever been observed with symptoms of the disease itself.
Conservation and Management
These bats are monitored with the other bat species in Florida as part of the Long-term Bat Monitoring Program, which seeks to keep track of bat populations throughout the state. The program achieves this by placing ultrasonic detectors across the state that pick up and record calls of nearby bats. In addition, the FWC performs yearly surveys of caves to check for the fungus that causes white-nose syndrome.
It is illegal to remove bats from structures or to otherwise handle them directly in the state of Florida. If you have bats in your house or other structure, please see our Living With Bats page to learn how to properly exclude them.
How You Can Help
We are always glad to have volunteer help with our bat conservation work, particularly with the Long-term Bat Monitoring Program in which volunteers help place and monitor our acoustic detectors. If you are interested in volunteering with this program or in helping in other ways, please visit our Bat Force website to learn more.
References
Arroyo-Cabrales, J., Miller, B., Reid, F., Cuarón, A.D. & de Grammont, P.C. (2016). Lasiurus borealis. The IUCN Red List of Threatened Species 2016.
Braun de Torrez E.C., Brown V.A., McCracken G.F., & Kunz T.H.. (2019). Sympatric Bat Species Prey Opportunistically on a Major Moth Pest of Pecans. Sustainability. 11(22):6365.
Clare, E.L., Fraser, E.E., Braid, H.E., Fenton, M.B., & Hebert, P.D.N. (2009). Species on the menu of a generalist predator, the eastern red bat (Lasiurus borealis): using a molecular approach to detect arthropod prey. Molecular Ecology, 18, 2532-2542.
Constantine, D. (1966). Ecological observation of lasiurine bats in Iowa. Journal of Mammalogy, 47: 34-41.
Emore, L. W., Miller, D.A., & Vilella, F.J. (2005). Foraging Area Size and Habitat Used by Red Bats (Lasiurus borealis) in an Intensively Managed Pine Landscape in Mississippi. The American Midland Naturalist. 153(2), 405-417.
Hickey, M. B. C., & Fenton, M.B. (1990). Foraging by red bats (Lasiurus borealis): do intraspecific chases mean territoriality? Canadian Journal of Zoology, 68(12), 2477-2482
Hickey, B., Acharya, L., & Pennington, S. (1996). Resource partitioning by two species of vespertilionis bats (Laiurus cinereus and Lasiurus borealis) feeding around street light. Journal of Mammology, 77: 325-334.
Kunz, T. H., Arnett, E. B., Erickson, W. P., Hoar, A. R., Johnson, G. D., Larkin, R. P., Strickland, M. D., Thresher, R. W., & Tuttle, M. D. (2007). Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses. Frontiers in Ecology and the Environment. 5 (6): 315–324.
Kurta, Allen (2017). Eastern Red Bats. Mammals of the Great Lakes Region (3rd ed.). Ann Arbor, MI: University of Michigan Press. pp. 74–77.
Newbern, J. & Whidden, H. (2019). Dietary analysis of three migratory bats in eastern Pennsylvania. Journal of the Pennsylvania Academy of Science, 93(1), 26-36.
NYNHP. Eastern Red Bat Lasiurus borealis. Retrieved from https://guides.nynhp.org/eastern-red-bat/
Shump, K. A. & Shump, A. U. (1982). "Lasiurus borealis". Mammalian Species (183): 1–6.
Simmons, J., Ferragamo, M., Haresign, T., & Fritz, J. (1996). Representation of Perceptual Dimensions of Insect Prey During Terminal Pursuit by Echolocating Bats. Biological Bulletin, 191:(1): 109-121.
Simmons, N. B. (2005). Genus Lasiurus. In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 458–459.
Whitaker, J. O.& Hamilton, W. J. (1998). Mammals of the Eastern United States. Cornell University Press. p. 123.