Aspects of the breeding behaviour of the kittiwake (Rissa tridactyla) before egg-laying

The breeding behaviour of individually marked Kittiwakes (Rissa tridactyla) that retained mates from the previous year (SAME) was compared, over the period from pair-formation to egg-laying, with those that changed mates (CHANGE). Courtship behaviour and sequences are described. Position of nest-site in colony and breeding experience did not differ in the two groups. Pair-formation was later in CHANGE pairs but dates of egg-laying were similar. Birds in CHANGE pairs used a less efficient means of nest-site defense by incorporating up to 19% more attendance as a pair. Birds in CHANGE pairs left their nest-sites unattended up to 13% less often. Rates of greeting were up to 2.5 times higher in CHANGE pairs and energy requirements were probably higher as a result. There was no evidence that frequency and timing of courtship feeding or copulation differed in a manner that could explain the lower reproductive success in CHANGE pairs reported by other workers. Breeding and non-breeding males interfered in the copulations of others. Breeding males were more often than expected members of CHANGE pairs and interfered most often during the two week period before their females laid eggs. The effects of interference on disrupted pairs was minimal. The adaptive significance of interference is discussed. In general, there was greater variance in measures of behaviour in CHANGE pairs and differences between the two groups were usually greatest during the first two weeks after pair-formation. The causation of these difference's are discussed in terms of mate familiarity and presumed differences in paternity assurance in the two groups. The consequences are discussed in terms of breeding efficiency and the costs of mate change.