The western mastiff bat is the largest western bat, reaching a weight of 2-2.5 ounces. They have long pointed wings (21-23") that allow for fast, sustained flight. Mastiff bats are one of the few bats with search phase calls low enough that people with good hearing can detect them. Most people do not realize that the sounds they are hearing are produced by bats. You can occasionally see and hear this bat in the late evening or on a moonlit night in Yosemite Valley.

Photo courtesy of Merlin D. Tuttle © Bat Conservation International.

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