As it is separated from the mainland by 3 miles (4.8 km) of water, few large mammals inhabit the island, except those that traverse the ice during the winter months. Rabbits, fox, raccoons, otters, mink, gray and red squirrels, and chipmunks are all common, as are the occasional beaver and coyote. Bats are the most abundant migratory mammals as crossing the water is no obstacle for them. There are many limestone caves serving as homes for the bats and many insects on the island for the bat to prey on.