Field Notes. 77 



upon the seeds of meadow-sweet. This rarity of the Bulfinch 

 in some parts of Airedale, especially during the breeding 

 season, can scarcely be attributed to a lack of suitable food, 

 but must be assigned to some other causes. The relative 

 distribution of many, if not most of our birds is so little under- 

 stood that one could wish for a monographer, not only in 

 every district but in every locality. — E. P. Butterfield, 

 Wilsden, December i6th, 1917. 



Pied Wagtails in Winter and on Migration in the 

 Bradford District. — I think that my friend, Mr. E. P. 

 Butterfield, is not strictly in accordance with the known facts 

 when he states that in most winters this species ' leaves this 

 district to a bird ' {ante 1917, p. 391). Although roughly 

 speaking the Pied Wagtail may be considered almost non- 

 existent in the neighbourhood during the darker months — 

 say November and December ; still it has been proved over 

 and over again in the past twenty-five years by the members 

 of the Bradford Natural History and Microscopical Society, 

 that there is not any month in the winter but that a single 

 bird or two may be reported. Usually it is a dirty, be- 

 draggled specimen at a sewage bed, mill dam, or some such 

 similar place. Occasionally they have been reported from 

 the lakes and ponds of our public parks in the depth of winter. 

 The great majority of Pied Wagtails leave this district in 

 September, though it is rarely that we see them in such numbers 

 as Mr. Butterfield describes as seen by him in September, 

 1916 ; which would most probably consist of birds that had 

 nested further north, and their families. They usually work 

 their way leisurely through the district in family parties, or 

 in collections of family parties. In spring, however, there is 

 generally a large and well-defined immigration of Pied Wagtails 

 near Saltaire, commencing as a rule on the last day or two in 

 March or early in April, and continuing until the 8th or loth 

 of April. At the commencement of this movement the males 

 are in the majority by well over 90 per cent., and gradually 

 the percentage is lowered ; although it is evident that many of 

 the females must follow much less ostentaciously later on. It 

 is a curious fact that I have never been able to observe this 

 great March-April movement in Wharfedale — only eight 

 miles away from Saltaire — but in another valley separated by 

 a fairly high moor. In Wharfedale the spring movement 

 appears to be leisurely throughout and similar to the autumn 

 exodus. If these spring immigrations are carefully watched, 

 and the birds individually and carefully scrutinised with a 

 good pair of field-glasses, a few male White Wagtails may be 

 recorded from time to time. A few females of the same 

 species may also be present, but I have great difficulty in 

 satisfactorily identifying them unless in the company of the 



1918 Feb. 1, 



