Breeding Biology of the Common Whitethroat Sylvia communis in Taleghan Area, Southern Slope of the Alborz Mountains

The breeding biology of the Common Whitethroat Sylvia communis was studied in Taleghan area in 1989. The average nest weight was 10.5 g (N=12) and average external and internal diameters were 8 cm (N=12) and 6 cm (N=12) respectively. The cup depth was 5.3 cm (N=12) and the height 8.2 cm (N=12). Female birds laid 3–6 eggs. Clutches varied in egg colour but eggs of a clutch were in similar colour. The egg colours were in greenish grey, olive and whitish blue. Eggs averaged 19 mm in length (N=8 nests) and 15 mm in width (N=8 nests); the average weight was 1.8 g (N=8 nests). One-day-old juveniles averaged 1.8 g in weight.