European Herring Gull (Larus argentatus) Science Article 7
Feeding behaviour and breeding parameters of Herring Gulls Larus argentatus were studied on Treberon, France, before (1983-88) and after (1989) a decrease of 80% in the amount of refuse dumped at a nearby tip. In 1989, fewer gulls visited the refuse tip than before the alteration, while intraspecific competition at the dump had increased compared with that in 1983-88. The decreased food availability affected all breeding parameters studied. The number of breeding pairs dropped by 11.5%. Mean clutch size decreased from 2.8-2.9 eggs per clutch in 1983-88 to 2.7 eggs per clutch in 1989. Egg volume in three-egg clutches dropped by 1.8% (b-eggs) to 3.6% (a-eggs). Hatching success decreased from 75% to 63%, while fledging success declined by 46%. Overall breeding success decreased from an average of 1.3 to 0.5 young per breeding pair (61% decline). In 1989, chicks were fed less than in previous years. Leslie’s matrix models showed that the asymptotic multiplication rate of the breeding population decreased from 1.1 in 1983-88 to 1.0 in 1989.
Pons J.M., ARDEA 80 (1): 143-150