Aspects of the breeding biology of the Kittiwake gull Rissa tridactyla at Marsden Bay, Tyne and Wear

Abstract

Although much research has been undertaken into the status and biology of the Kittiwake Rissa tridactyla studies of a colony over an extended period are scarce with the notable exception of the North Shields colony for which 31 years of data were summarized by Coulson and Thomas (1985). The nearby colony at Marsden Bay, Tyne and Wear had however been the focus of study in the 1950s (Coulson and White 1956) and the 1970s (Dixon 1979). It was considered that a similar study in the early 1990s could be usefully combined with a review of data from these two previous periods. Since the colony's formation in 1931 the nest count has increased from 308 in 1937 to 5768 in 1992. After rapid and steady growth through the 1940s and 1950s a period of relative stability occurred in the 1970s with about 4,600 nests present. In the last 15 years numbers have again risen substantially. Continuing changes in the cliff structure due to erosion are affecting the availability of nest sites and hence the number of nests. Changes in the breeding biology have resulted in the Kittiwakes spending less time at the colony each year. Their later arrival in the spring has had little effect on the mean date of laying perhaps due to a more synchronised arrival of the colony. Evening departure by birds from the colony in the pre-breeding period was found to be related to the time the birds arrived in the colony in the spring and their subsequent attendance on the nest site. Chick growth rates were slightly lower than in the 1950s and 1970s at North Shields, and chick neglect was frequent in 1992. However these factors did not appear to influence the fledging success.