SWART AN (1959) Short announcements: A mixed breeding pair of British and continental forms of the Yellow Wagtail. LIMOSA 32 (4): 228-228.

A mixed breeding pair of British and continental forms of the Yellow Wagtail was recorded on waste grounds on the southern border of Amsterdam in 1959. The subspecific identity of the parents was confirmed by several observers. The pair apparently raised two broods, the young of the first brood leaving the nest about 6 June, those of the second brood about 16 July Motacilla flavissima = Motacilla flava flavissima Yellow Wagtail

[free pdf] [dutch summary]