CONTINENTAL RACIAL FORMS, ETC. 103 



and rather doubtful record), the Isle of May, and Aberdeen, 

 and is an occasional passage migrant in Shetland. The only 

 times we saw the Blue-headed Wagtail on the Isle of May were 

 on the 13th and 14th May 191 3. The picture rises before 

 us, of the plateau on the island covered with rough grass, 

 and with here and there pools of water, the result of the 

 recent rain. By one of these pools a Blue-headed Wagtail 

 was feeding, a beautiful bird with blue-grey head and very 

 distinct white eye-stripe. We watched it through our 

 glasses for some time, but when we attempted to approach 

 nearer, it rose at once and flew off. Syke's Wagtail 

 {Motacilla fiava beema), which breeds in West Siberia, has 

 once been procured on Fair Isle, on 13th May 1910. It 

 differs from Motacilla flava fiava in having a shorter tail 

 and lighter head, the superciliary stripe is very broad, and 

 the lower part of the ear-coverts is mixed with white. The 

 Grey-headed Wagtail {Motacilla fiava thunbergi) breeds 

 in Northern Europe and Siberia, and has occurred several 

 times on the Isle of May and in Orkney, and is an occasional 

 passage migrant in Shetland. We have several times seen 

 the Grey-headed Wagtail on the Isle of May in spring — the 

 features which strike one most being the shortness of its tail 

 and its note. This last is very loud and ringing, and quite 

 different from that of the other Wagtails with which we are 

 familiar. It is always very wild and unapproachable. The 

 White Wagtail {Motacilla alba alba) breeds in Europe 

 generally, and is a regular passage migrant along our coasts, 

 more common on the West than on the East. It reaches as 

 far as St Kilda, where it is one of the commonest birds of 

 passage, and has bred on several occasions in Shetland. 

 We have often seen this bird on passage, and have noticed 

 that the note differs very distinctly from the familiar 

 " chizzit" of the Pied Wagtail. The differences of plumage 

 between this form and the Pied Wagtail have long been 

 known, and need no description here. 



The Northern Tree-creeper {Certhia familiaris 

 fajiiiliaris), which breeds in Northern Europe and Siberia, 

 differs from our resident bird in having the brown tints in 

 the upper plumage of a light yellowish tone, as against the 



