My Bantam Lake

Eastern Red Bat

Written on 06/27/2018

Lasiurus borealis

Lasiurus borealis are fast flying bats that live throughout the Americas. They tend to choose habitats that are sparsely to moderately populated by humans and are rare in heavily urbanized areas. Red bats are medium sized bats having a total length of 93 to 117 mm. Pelage varies in color from a brick red to a yellowish red. The fur is white at the tips giving these bats a frosted appearance. In general, female bats appear more frosted compared to males, and males have a redder color than females. Mating takes place in flight and copulation usually occurs in August or September. It takes young red bats about five weeks to learn how to fly and forage on their own. Red bats are migratory, arriving in the northern climates in mid-April and leaving in late October. Lasiurus borealis choose roosting sites in dense foliage. They may be visible hanging from branches or leaves but their coloration helps to camouflage them from predators. Their red coat is particularly helpful at camouflaging them in sycamore, oaks, elm, and box elder trees and they seem to prefer these trees as roost sites. Red bats use echolocation to locate prey. They use both broadband and narrow band calls. Search phases of calls use long calls with low pulse repetition of narrow band frequencies. Red bats are insectivorous. They capture insects while flying like many other insectivorous bats. Red bats make one pass through a concentration of potential prey, fixing on a target within 5 to 10 m. They attack insects, on average, every thirty seconds and are successful fourty percent of the time. If a bat is stalking a moth using echolocation the moth can hear this and will try to flee the attack by diving. The bat will follow the moth into a steep dive and often will pull away within inches of the ground. Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%.


Source: Lasiurus borealis Red Bat, Animal Diversity Web, University of Michigan Museum of Zoology