부산대학교 도서관

The results of a study of the feeding biology of nine sea-bird species breeding on the Farne Islands Northumberland, showed that: 1. Fish is the predominant food of all the species studied. 2. There is a considerable overlap between the size and species of fish taken by each of the sea-bird species. 3. The food obtained by each species is not necessarily taken from the same area, each species showing differences in the average distance travelled in search of food and the depth at which food is obtained. 4. The three species of terns which were studied were close to the limits of their physical ability to collect food whereas the larger sea-birds had considerable reserve of time which could be utilized for fishing should fish be less abundant. 5. During 1961 and 1962 there was little evidence to suggest that large broods were reared less successfully than those with only one chick. 6. Chicks on the Farne Islands grew more rapidly than did chicks of the same species in the Arctic, implying that available food was at least as abundant in this area as in the Arctic during the richly productive summer months. These results suggest that during the study there was a superabundance of food and there was little or no starvation of the young; if food should at any time be less abundant, then it is possible that the different feeding areas may well limit any interspecific competition. No evidence was found of competition for any resource occurring between any of the congeneric species breeding on the island, even when there was no apparent ecological division between species. It is concluded that in the fish-eating species of sea-birds breeding in the study area, brood size is not limited by food supply.