Other mammals preyed on occasionally include shrews, squirrels (largely chipmunks and red squirrels), various other mice species, flying squirrels, moles and bats. Also supplementing the diet are small birds, with passerines such as swallows, sparrows, kinglets and chickadees favored. However, larger birds, up to the size of rock pigeon (which are typically about 4 times as heavy as a saw-whet owl) can even be taken. On the Pacific coast they may also eat crustaceans, frogs and aquatic insects. Like many owls, these birds have excellent hearing and exceptional vision in low light.