159 



NESTING STATUS OF THE BLACK -HEADED GULL 

 IN YORKSHIRE.* 



H. B. BOOTH, F.Z.S., M.B.O.U. 



In 1 88 1, when Messrs. Clarke and Roebuck published their then 

 excellent ' Handbook of the Vertebrate Fauna of Yorkshire,' 

 there was but one breeding station of the Black-headed Gull 

 in the West Riding, viz., the large guUery on the Yorkshire 

 portion of Thorne Waste, in the extreme South-west. In 

 fact it might be said to have then been the only breeding 

 station in Yorkshire, as the Riccall Colony was extinct, and 

 as a boy at school in York at that time, I well remember 

 the great eagerness there was to obtain the eggs of the few 

 pairs of Black-headed Gulls that were still hanging about 

 Strensall Common, on the site of the former large gullery. 

 But during the last twenty years a very different state has 

 existed, particularly in the West Riding, where numerous 

 breeding stations have sprung up ; although they are little 

 known outside the county. Unfortunately, perhaps, ' The 

 Birds of Yorkshire,' did not particularly refer to the change 

 that was then taking place. From about the year 1894 to 

 a little into the twentieth century, bird-lovers, in the York- 

 shire dales, were puzzled and baffled by the increasing numbers 

 of adult Black-headed Gulls appearing year by year, which 

 spent most of their time at the numerous sewage beds which 

 had been laid down ; particularly in Airedale. Many reports 

 of their nesting were investigated, but for the first few years 

 all proved to be incorrect ; but later it became known that 

 several nesting stations had been established. These mostly 

 have increased, both in the numbers of the birds, and in the 

 number of the breeding sites, although some, such as those at 

 Fly Flat and Keighley Moor Dam, always appear to have 

 small struggling colonies. In our opinion the birds that were 

 forming these new breeding stations were coming from the 

 west, and chiefly from the huge gullery at Cockerham Moss, 

 about sixteen miles south of Lancaster, which has been extinct 

 for about a dozen years now. There were not any bird- 

 marking schemes in those days, or we might have had more 

 precise information. However, I have included particulars 

 of ' ringed ' birds that have occurred in later years, and they 

 all point to a migration from more western breeding stations. 

 More investigations at the various nesting stations should 

 be undertaken, and a full, and as correct a list as possible, 

 be made for the county for future reference and comparison. 



* Read at the meeting of the Vertebrate Section of the Yorkshire 

 Naturalists' Union, held at Leeds on February 19th, 1921, and revised. 



1921 May I 



