Little Brown Bat (Myotis spp.): This common species of bat is found throughout California roosting in small groups. They feed on small flying insects and can eat half of their body weight in insects each night.
Mexican Freetail Bat (Tadarida brasiliensis): This bat is the most frequently encountered bat in Alameda County. Throughout California, they often roost in large groups under bridges, in caves, mines, and buildings below 1500 feet in elevation. Also called the Brazilian free-tail, this migratory bat has a colony 100,000 members strong at Lava Beds National Monument. It is one of the fastest flying bats in California with a top speed of 25 mph.
Hoary Bat (Lasiurus cinereus): This large, heavily furred bat is often found roosting alone in dense foliage in trees. It has a dark brown fur with white tips, giving it a frosted or “hoary” appearance. It feeds mainly on moths and beetles.
Townsend’s Big-Eared Bat (Corynorhinus townsendii): The Townsend’s bat is rare in Alameda and is a California Species of Special Concern. The unique large ears are very noticeable on this medium sized, light brown bat. The Townsend’s bat roosts in large colonies in large hiding places like caves, mines and abandoned buildings.
Video by: National Geographic.