Hawks are birds of prey that is known as elil to small land animals, including rabbits.
A hawk kills Violet when she ventures out into the open to flayrah.
In Friend and Enemy, Campion was attacked and carried into the air by a hawk, but managed to escape by kicking at the bird's head causing it to let him go. The hawk circles around briefly before it flew off.
In The Invasion, a hawk was attracted by the herd of sheep that got loose from their farm in a storm and were feeding upon the down, posing a threat to both the rabbits of Watership Down, and Pipkin's new friend, Frost.
In The Nestling, a mother hawk leaves her young to hunt for food. The female hawk spotted General Woundwort and attempted to attack him, but was overpowered and killed. The orphaned hawk, later named Skree, was taken in by the Junior Owsla, and became the aerial scout for the Watership rabbits for the remainder of the series when Kehaar left the down with a new mate.