The Primary Moult of the Dunlin Calidris alpina at the Wash

Abstract

The primary moult of the Dunlin Calidris alpina alpina at the Wash, East England, is described. A new statistical method for estimating the duration of the moulting period of a population is developed and individual moult duration is also considered, using population parameters and data from retraps. Differences were found in the timing and duration of the moulting season in different years. Within any one year late moulting individuals moulted more rapidly than early birds. The adaptive significance of these differences within the annual cycle is discussed.