The animal on the cover of Learning the Unix Operating System is a horned owl. The
horned owl is the most powerful of North American owls, measuring from 18 to 25
inches long. This nocturnal bird of prey feeds exclusively on animals-primarily rab-bits,
rodents, and birds, including other owls. It locates these animals by sound
rather than sight, since its night vision is little better than ours. To aid its hunting, an
owl has very soft feathers that muffle the sound of its motion, making it virtually
silent in flight. A tree-dwelling bird, it generally chooses to inhabit the old nests of
other large birds such as hawks and crows, rather than build its own nest.