VJ^LLOIV WAGTAIL. 69 



the egg-. Average measurement, 78 inch in length, by 

 ■56 inch in breadth. Incubation, performed chiefly by 

 the female, lasts about fourteen days. 



Diagnostic characters : As previously remarked, 

 the eggs of the Blue-headed Wagtail so closely re- 

 semble those of the Gray Wagtail and the Yellow 

 Wagtail, that no character can be given by which they 

 can be separated. The eggs require careful identifi- 

 cation ; but it should be remembered that the present 

 species is very rarely known to breed within our area. 



Family MOTACILLID.-E. Genus Motacilla. 



YELLOW WAGTAIL. 



Motacilla raii, Bonaparte. 

 Double Brooded. Laying season, April and June. 



British breeding area : A common summer visitor, 

 widely distributed during the breeding season throughout 

 England, with the exception of Cornwall and Devon. 

 In Scotland its principal breeding area lies south of 

 Stirling. In Ireland it becomes even more local, and is 

 only known to nest in the neighbourhood of Lough 

 Neagh, and the vicinity of Dublin. 



Breeding habits : Marshy meadows and pastures, 

 broads, and commons are the favourite breeding-grounds 

 of the Yellow Wagtail. In this respect it closely resem- 

 bles the Blue-headed Wagtail ; in fact the habits of the 

 two birds, like those of the Pied and White Wagtails, 

 are almost precisely alike. This Wagtail appears to 

 pair annually, shortly after its arrival in spring ; although 

 it is probable that some pairs remain united for life, as 



