Diet and growth of glaucous gulls at a large Arctic goose colony

We examined the diet and growth of glaucous gull (Larus hyperboreus) chicks at Karrak Lake goose colony in 1994 and were especially interested in how these factors were affected by geese leaving the colony after goose hatch. Insects and bird prey each occurred in about 80% of regurgitated pellets du ring the first week after hatch of gulls. Thereafter, the frequency of inse cts in pellets diminished to < 20%, whereas the frequency of bird parts and eggshells increased to about 100 and 80%, respectively, and remained high in gull diets during the 6 weeks of this study. We observed no effect of la ying order on the size of gull eggs, nor any effects of chick sequence on g rowth or survival of chicks, suggesting that food was abundant during egg-l aying and possibly early in chick rearing. Overall, both the growth rate an d final size of chicks varied among nests, and chicks from small broods gre w larger than chicks from large broods. Egg size and hatch date had no effe ct on growth. We suspect that brood size emerged as an important effect on growth, because food abundance declined as gull chicks grew older and brood competition came in to play.