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 Animal Fact Sheet:  Townsend's big-eared bat

Identifying Features

Townsend's big-eared bats (Corynorhinus townsendii) are a medium-sized bat with very long ears. Their fur is pale gray or brown above and buff colored on the underside. This bat's ears are enormous, reaching a length of 38 mm. When the ears are laid back they extend to the middle of its body. The face is marked by two large glandular lumps on either side of its nose.

Migration/Hibernation

These bats do not undertake a major migration and are generally rather sedentary. The hibernation roosts are usually abandoned mines or caves that have low and stable temperatures. While hibernating they hang solo or in small groups in the open, with their fur erect to provide maximum insulation and with their ears coiled back.

Habitat

Townsend's big-eared bats will use a variety of habitats, almost always near caves or other roosting areas. They can be found in pine forests and arid desert scrub habitats. When roosting they do not tuck themselves into cracks and crevices like many bat species do, but prefer large open areas.

Range

These bats can be found throughout the western U.S. from British Columbia down into central Mexico.

Wild Status

They are generally in decline in most areas, and are listed as an Endangered species in Washington, a Sensitive species in Oregon, a Species of Special Concern in Texas, Montana and California. Because this species is sensitive to disturbance, it has been documented that they will abandon roost sites after human interference. In large portions of its western range, their dependence upon abandoned mines has put them at risk. Pesticide spraying also may affect their food source.

Diet

They specialize in eating moths and other insects such as beetles, flies and wasps. Townsend's big-eared bat is usually a late flier and will forage along the edge of vegetation.

Predators

It is assumed as with many bat species that predators can include snakes, owls, cats, raccoons and hawks.

Reproduction

Summer maternity colonies range in size from a few dozen to hundreds of individuals. These colonies form between March and June with pups born between May and July. Maternity colonies choose sites that have warm, stable temperatures for pup rearing. Males remain solitary during the maternity season. Young are born in mid-June with about 90 percent of all females in the nursery colonies producing young. Only one young is born per female. Pups will begin to flying at about 3 weeks old.

Life Span

These bats live from four to ten years; maximum life span recorded is sixteen years.

Size

Their wingspan is12-13 in (30-34 cm) and they weigh between 0.3-0.5 oz (9-14 g).

Extra Fun-facts

  • When it's roosting or hibernating, Townsend's big-eared bat curls up its long ears so they look like rams horns.
  • When flying they can rapidly extend or contract their ears. When flying with their ears extended the ears point forward and are nearly parallel to their body.