PROSPECTING IN THE KITTIWAKE, RISSA-TRIDACTYLA - DIFFERENT BEHAVIORAL-PATTERNS AND THE ROLE OF SQUATTING IN RECRUITMENT

Long-lived birds, such as seabirds, generally have a prebreeding prospecting period before recruitment. In the kittiwake, some birds, called squatters, occupy unattended nests or nests with unattended chicks which arc not their own. In this study squatting mainly involved failed breeders and prebreeders, i.e. birds looking for a breeding site. Three categories of prospectors were distinguished on the basis of the sites where they landed (squatters on chicks, squatters on nests and non-squatters which occupied non-breeding sites only). Squatters on chicks were the oldest and non-squatters the youngest prebreeding prospectors. These squatters on chicks were implicated in a process of geographical stabili- zation, settlement, appropriation and pair formation, more than other prebreeding prospectors. Non-squatters showed the lowest attendance at the colonies. They were not attracted to breeding activities as much as the squatters. Squatters on nests wandered more than other prebreeding prospectors and visited several breeding places. These three categories of prospectors reflected progressive stages in the ontogeny of recruitment. The respective proportions of prebreeders recruited in the following year confirmed these results. More generally, prospecting in birds can be interpreted as a behavioural mechanism to assess the environmental quality of different breeding places prior to breeding. © 1993 The Association for the Study of Animal Behaviour.