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 Nestling, a mother hawk leaves her young to hunt for food. The female hawk spotted General Woundwort and attempted to kill 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 Down rabbits for the remainder of the series when Kehaar left the down with a new mate.