A colony of sea birds is visited in a study of breeding success. It is proposed that birds with nests at the top of the cliff will be more successful than those nesting at the bottom. Early egg laying is taken as a measure of success. The cliff is arbitrarily divided into a top and a bottom part. There were 22 inhabited nests in the top part and 16 in the bottom part. At this point in the breeding season, 40% of all nests contained eggs. The number of inhabited nests containing and not containing eggs was counted in each part.