Intraspecific Variation in the Egg Size of the Pied Avocet

-Egg size variation in the Pied Avocet Recurvirostra avosetta was studied at seven breeding colonies on the North Sea coast of Schleswig-Holstein in Germany in 1999. A total of 999 eggs from 283 clutches were measured during the whole breeding period. Egg size was very variable and most variance was due to differences between clutches. Eggs within a clutch were relatively uniform in size. Size differences due to laying order could not be detected. Egg size did not differ between four-egg and three-egg clutches. Egg size, clutch size and the length of the incubation period decreased as the season progressed. Egg size and chick size at hatching were positively correlated. Received 31 July 2000, accepted 20 November 2000.