Two clutches in a nest of the Blue-headed Wagtail. - N.N. Balatsky. - Berkut. 5 (1). 1996. P. 90.
In environs of the town of Noyabrsk (Tyumen region) a nest with an unusual clutch was found 29.06.1995. There were 9 eggs and 1 nestling there. 3 eggs lay near the nest. The analysis of the eggs showed that both clutches (6 and 7 eggs) had been laid by one bird. It is connected with the cold weather. The repeated clutch was laid in the same nest. [Russian].