SURVIVAL OF THE KITTIWAKE IN RELATION TO SEX, YEAR, BREEDING EXPERIENCE AND POSITION IN THE COLONY

Continuous monitoring of a colony of marked Rissa tridactyla on a warehouse in North Shields, Tyne and Wear, NE England, has led to 34 yr of data on the survival of individual birds, as well as on breeding success, mate fidelity and site tenacity. Generalized linear modelling showed that the annual adult survival rate of the kittiwake varied according to sex, time-period, breeding experience and nest position. The effect of each factor was apparently independent of those of the other three. Average annual survival rate of adult males was 78%, of females 82%, after allowing for the effects of factors other than sex. First-time breeders survived as well as experienced birds which had been breeding for up to 12 yr; >12 yr, annual survival rate dropped by 11%. After removing the effect of age, the annual survival rate was highest during 1958-61, lowest during 1982-85; between these periods, the mortality rate tripled. Kittiwakes which settled in either the centre or the edge of the colony did so for life. Males and females that nested in the centre survived better than ones on the edge (average 81.2% vs 78.7% yr-1). The difference probably reflected a segregation between intrinsically fit and less fit individuals: the 2 areas were equally safe to nest in, but centre birds had a higher breeding success and lifetime reproductive fitness. -from Authors