 In all accipitrids, the base of the upper mandible is covered by a fleshy membrane called the cere, which is usually yellow in colour.The tarsi of different species vary by diet; those of bird-hunting species, such as sparrowhawks, are long and thin, whilst species that hunt large mammals have much thicker, stronger tarsi, and the tarsi of the snake-eagles have thick scales to protect from bites.The plumage of the Accipitridae can be striking, but rarely utilises bright colours; most birds use combinations of grey, buff and brown.