Watch: Biologists count thousands of bats in eastern Washington

Washington Department of Fish and Wildlife biologists across the state conduct annual bat surveys each spring. In eastern Washington, this involves surveying known “maternity colonies” of female bats that take up residence together to give birth to pups. In some places, these colonies are in caves, but in eastern Washington they tend to be in structures abandoned by humans or large “condos” built especially to house bats.

Surveying bats annually lets biologists monitor the health of these colonies. If counts show a noticeable drop in the number of bats in a colony, it is a signal that something could be wrong.

Watch the video below to see how biologists count these fast-moving creatures in the dark.