THE TERRITORIAL BEHAVIOUR OF THE HAWFINCH COCCOTHRAUSTES COCCOTHRAUSTES.

Summary. The territorial behaviour of the Hawfinch Coccothraustes coccothraustes is examined. Some Hawfinches breed in small colonies, others in isolation. Pair formation takes place before the dispersal of the winter flock, following an unusually protracted courtship. Females are initially dominant and males learn to recognize them by their reactions to attempts to trespass beyond the normal limits of their “individual distance”. Copulation cannot take place in the flock because of interference by other individuals. Males then withdraw to take possession of the nest trees in the colony; these are temporarily defended from other males. Females later join the males and there follows a marked change in the behaviour between the sexes. Copulation takes place in the relative seclusion of the nest tree and its immediate surroundings. Individual territorial activity ceases completely once the eggs are laid and is replaced by communal territorial defence against predators. Solitarily breeding pairs, thought to be inexperienced birds, defend a small territory surrounding the nest for the whole of the nesting period. This area is insufficient to ensure an adequate food supply for the nestlings. Breeding success of solitary pairs is one third less than that of colonial pairs, because of restricted ability to defend the nest against predators. The establishment of breeding colonies is therefore assumed to have superior survival value. Song is shown to play an insignificant part in the breeding biology of the species.