BREEDING SUCCESS OF BRITISH KITTIWAKES RISSA-TRIDACTYLA IN 1986-88 - EVIDENCE FOR CHANGING CONDITIONS IN THE NORTHERN NORTH-SEA

Data on breeding success from 35 British and 1 Irish kittiwake colony were collected. At each colony the mean number of young fledged per completed nest was similar in 1986 and 1987, but at North Sea colonies success was significantly poorer in 1988. Colonies in the northern North Sea showed a negative relationship between breeding success and latitude in 1986 and 1987; in 1988 there was a significant N-S trend in success over the whole length of E Britain with colonies in the south being more successful than those in the north. In North Sea colonies most breeding failures occurred at the chick stage, but on the west coast some birds did not lay whilst others failed during incubation or soon after hatching. Amongst North Sea colonies it seemed likely that food shortage during chick rearing was responsible for the low breeding success, a conclusion consistent with the finding that a series of poor recruiting year classes had caused a decline recently in the Shetland stock of sandeels Ammodytes spp. -from Authors