Species Spotlight: Hoary Bat

02.22.17

Pop quiz: What small mammal can be found in south-eastern Canada, Hawaii, Bermuda, and Iceland?

Answer: The hoary bat (Lasiurus cinereus).

The hoary bat holds the title of the most widespread bat species in the Americas, with a transcontinental range stretching from south-eastern Canada to Hawaii.

The hoary bat is a migratory bat species, which means instead of spending winter months hibernating in large colonies, this solitary bat migrates to warm winter habitats. Summers are spent concealed in the foliage of mature deciduous and coniferous trees, typically near the edge of a clearing. Their distinct grey-white coloration (for which the bat is named for), and furred tail membrane are prime adaptations for this habitat, explains Bat Conservation Internationals Senior Director of Conservation Science, Winifred Frick.

What is neat about the hoary bat is that they will hang out in the leaves of trees and use their furry tail membrane to wrap themselves up like their own little personal sleeping bag. They typically hang from one foot and look like a dry leaf in a tree.

Hoary bats may fly as fast as 13 miles per hour and as high as 8,000 feet during their long-distance migrations in the autumn and spring, stopping at night to hunt for moths, mosquitoes and occasionally other bats.

These bats are not the most social of creatures, preferring to lead mostly solitary lives tucked away in the tree foliage. After mating in autumn, females will move to the northern, eastern, and central United States to give birth, often to twin pups (rare in bat species) in mid-May to early July. Males will remain in the mountainous areas of the western United States. 

Though, much like running into George Clooney at your local store, humans have a small chance of ever encountering a hoary bat. These solitary bats seldom enter houses and spend the daylight hours well concealed in the tree foliage. This has given researchers a handicap as they try to decode the bats behavior.

Answering questions like how many bats are there?, is difficult because you cant just count them coming out of the cave. As they move around between multiple tree roosts and over long distances it is hard to mark and recapture them, explains Frick.

Were just now on the cusp of being to able to answer some interesting questions because of improving technology. For example, it always was assumed they were migratory and not hibernating, but now we are thinking they might be going through periods of torpor, even though they are in the trees, says Frick. Which begs the question, what else are these bats hiding from us?

Unfortunately, we may be running out of time to discover the secrets of the hoary bat, as the species is facing an increasing number of threats. In addition to deforestation and human disturbance, hoary bats are heavily impacted by wind turbines. Although currently considered common across North America, an estimated 76,000 152,000 hoary bats are killed each year by collisions with wind turbines. Scientists from Bat Conservation International are working with the wind industry as well as conservation and government partners to develop and implement solutions to reduce this mortality rate. By changing how wind turbines are managed and developing acoustic deterrents to discourage bats venturing near the spinning blades, BCI has high hopes that the wind industry can be sustainable not only for our climate, but the future of our bat species as well.

Bat Stats
Binomial  Lasiurus cinereus
Family  Vespertilionidae
Colony Size  Solitary
Wingspan  13 16 inches (34 41 cm)
Diet  Insectivorous
Status  Least Concern
L.c. semotus (Hawaiian hoary bat subspecies)   Endangered.