Postfledging crèche behavior in the European shag

Abstract

Formation of a postfledgling creche in the European shag Phalacrocorax aristotelis on the Cies Islands (northwest Spain) was studied. There was no relationship between the number of birds in a creche and environmental temperature. Moreover, the number of juveniles in the creche was not correlated with adult peck rate per juvenile. Also, predation was not reported on the studied population. Therefore, their postfledging creche did not serve as protection from thermal stress, aggressiveness of adults, or predators. In the creche studied, fledglings are faithful to their perch, which serves as a functional unit where they form a group consisting of stable members. I postulate that there may be advantages in the formation of creches, which allow adults to be able to locate their young and continue their postfledging parental care and also enable chicks to exercise and develop fishing skills. Adults remained in the creche during the entire period, but their number depended on the hour and tide, which would be associated with the effectiveness of fishing according to these factors. Moreover, creches may facilitate finding mates and forming feeding groups.