BREEDING SUCCESS, DIET, AND BROOD NEGLECT IN THE KITTIWAKE (RISSA-TRIDACTYLA) OVER AN 11-YEAR PERIOD

Seabirds are Frequently used as indicators of the state of the marine environment. The kittiwake (Rissa tridactyla) is a common and widespre ad surface-feeding seabird often used for such a purpose. Data were co llected on the food of chicks, breeding success, and chick neglect at a colony in south-east Scotland every summer in the period 1986-1996. Breeding success declined significantly over the period and breeding b ecame later. In one year, many adults failed to breed. A similar decli ne in breeding success was also recorded at colonies over a 250-300 km section of coast in south-east Scotland and north-east England. Sande els (Ammodytes marinus), especially 0-group fish (young of the year), made up the bulk of the diet in all years; herring (Clupea harengus) a nd sprat (Sprattus sprattus), waste from trawlers, and planktonic Crus tacea was of lesser importance. Nesting success increased significantl y with the proportion of 0-group sandeels in the diet of chicks and wi th the average energy value of 0-group sandeels, variables which were significantly and positively correlated. Clupeids and trawler waste we re probably taken only when sandeels were unavailable. Brood neglect w as not a good indicator of annual total breeding success. The decline in nesting success appeared to commence before the development of a la rge local industrial fishery for sandeels. (C) 1997 International Coun cil for the Exploration of the Sea.