Halloween Sightings: Eastern Red Bat

October 18, 2019 • Madison Square Park Conservancy

An Eastern red bat, Lasiurus borealis, one of our native tree nesting bats, was spotted this month just in time for Halloween. The Eastern red bat can be found in trees anywhere east of the Rockies, making it one of the most common bats in the United States. Eastern red bats nest in trees, shrubs, roofs generally away from dense human habitation, though they are occasionally spotted in crowded urban areas. When roosting they suspend themselves from a single leg resembling an autumn leaf clinging to a branch. Their rusty coloration is their principal means of defense against predation by opossum and birds of prey. Their preferred nesting sites include sycamore, oak, and elm trees. The abundance of these trees at the park is one of the reasons that this species has been sighted despite generally avoiding urban areas, and they are just one of several bat species that our staff has observed nesting here.

Eastern red bats are large for North America, with an average wingspan of 13 inches. Most bats spend the warmer months throughout their range, migrating to the southern reaches looking for warm weather and abundant insects. However, some Eastern red bats do not migrate and have been seen active in the colder areas of their range. During winter, L. borealis hibernates to conserve energy and limit exposure to low temperatures. The increasing number of warm days during the winter and decreasing insect populations has greatly impacted local bat populations as warm days awaken bats from migration only to find no insects to eat.

Eastern red bats, like many bats, are voracious insectivores, consuming insects of all kinds.
Beginning their hunt at dusk, Eastern red bats are quick fliers and prefer to hunt within 500 meters of a light source, likely as their insect prey are attracted to the light. Prey varies depending on the location and season, but the most common insects eaten are beetles and moths. L. borealis has a very distinct means of attack, following their prey in a very steep dive that can take them within inches of hitting the ground before they pull up. This is often mistaken for aggression on the part of the bat, as people are unable to see the tiny moths the bats snack on.

Bats are important members of our ecosystem. Their diet of insects including mosquitoes, is beneficial to humans and helps prevent the spread of mosquito borne illnesses.

Logged sightings on iNaturalist help Madison Square Park Conservancy understand our urban ecosystem and allow us to create a Park that benefits people, plants, and animals.

Posted by mspceco mspceco, October 18, 2019 16:57


Photos / Sounds



Eastern Red Bat Lasiurus borealis




September 30, 2019 12:28 PM EDT


We've never seen a bat this color in the park. It had a rich chestnut brown colour to its wings. As we approached it, the bat started flapping its wings and flew away from the ground. 


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