The Townsend’s Big-Eared Bat has a body measuring up to 4 inches (10 cm) with a wingspan of 11 inches (28 cm). It has a dark brown body with lighter brown fur on the sides. As the name indicates, its most recognizable feature is the large, flexible ears which measure up to 1.5 inches or 3.8 cm. This oversized feature aids the bat with its echolocation, which is sometimes referred to as biological sonar. Echolocation involves the animal emiting a high-frequency tone into the environment which then bounces off physical features. The resulting echoes allow the bat to determine distances, sizes and even types of objects and animals around them.
An insectivore, the bat feeds almost exclusively on moths and butterflies, although it may occasionally feed on beetles, flies and vegetation. It is both swift and agile when airborne, able to snatch up insects in flight.
These bats will hibernate during the winter months but do not migrate over large areas. They breed during the spring and usually produce a single pup in the summer.
The bat can be found throughout North America from Canada to Mexico. Colonies will roost in large subterranean areas such as caves, mines, tunnels and abandoned buildings, emerging after dark to feed.
The populations of this bat have been in steady decline over the past few decades. It is listed as endangered in Washington state and is considered a State Sensitive Species in Oregon. Thus far, the Townsend’s Big-eared Bat has not been affected by White Nose Syndrome, a deadly fungus which has killed millions of bats in the United States and Canada. Why this bat species is not affected by the fungus is under investigation by fish and wildlife authorities.
Photo credit: USFWS