Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) emerging from cave, North Carolina

Claudio Contreras / Townsend's big-eared bat (Corynorhinus townsendii) roosting, Milpa Alta Forest, Mexico, September

Claudio Contreras / Townsend's big-eared bat (Corynorhinus townsendii) roosting, Milpa Alta Forest, Mexico, September

Claudio Contreras / Townsend's big-eared bat (Corynorhinus townsendii) roosting, Milpa Alta Forest, Mexico, September

Claudio Contreras / Townsend's big-eared bat (Corynorhinus townsendii) roosting, Milpa Alta Forest, Mexico, September

Claudio Contreras Koob / Townsend's big-eared bat (Corynorhinus townsendii) roosting, Milpa Alta forest, Mexico, September

Michael Durham / Townsend's big-eared bat (Corynorhinus / Plecotus townsendii) flying out of cave at dusk, Derrick Cave complex, Central Oregon, USA, August.

Michael Durham / Townsend's big-eared bat (Corynorhinus townsendii) flying out of cave at dusk, Derrick Cave complex, Central Oregon, USA, August.

Michael Durham / Solitary male Townsend's big-eared bat (Corynorhinus townsendiii) roosting in an abandoned house, Central Oregon, USA, June.

Michael Durham / Biologist installing a motion sensor in the abandoned Smoking Dump gold mine to help scientists understand why sensitive bat species like Townsend big-eared bats (Corynorhinus townsendii) use the mine...

Barry Mansell / Townsend's big-eared bat (Corynorhinus / Plecotus townsendii) roosting on tree, Arizona, USA

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) flying out of cave, Craters of the Moon National Monument, Oregon

Barry Mansell / Townsend's big-eared bat (Corynorhinus / Plecotus townsendii) in flight, Arizona, USA

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) flying in abandoned mercury sulfide mine, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) pair flying in abandoned mercury sulfide mine, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) flying in abandoned mercury sulfide mine, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) roosting in an abandoned house, Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) roosting in Gold Stake Mine, Coleville National Forest, Washington

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) roosting in Gold Stake Mine, Coleville National Forest, Washington

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) pursuing a Spanworm Moth, digital composite

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) exits a cave in the Derrick Cave Complex, a series of lava tubes and lava bubbles, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) pair exit a cave while a third flies in the background in the Derrick Cave Complex, a series of lava tubes and lava bubbles, dusk, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) exits a cave in the Derrick Cave Complex, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) exits a cave in the Derrick Cave complex, a series of lava tubes and lava bubbles, dusk, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) exits a cave in the Derrick Cave Complex, a series of lava tubes and lava bubbles, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) exits a cave in the Derrick Cave Complex, a series of lava tubes and lava bubbles, central Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) flying at night, John Day Fossil Beds National Monument, Clarno Unit, Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) male roosting on a rock, John Day Fossil Beds National Monument, Clarno Unit, Oregon

Michael Durham / Townsend's Big-eared Bat (Corynorhinus townsendii) leaving cave, Pond Cave, Craters of the Moon National Monument, Idaho