SUGGESTIONS AND GUESSES 123 



what is the effect on a flying bird which suddenly 

 enters one of these pockets ? 



The lesser black-backed gull also crosses England 

 in large numbers ; its movements are more notice- 

 able than those of the herring gull, common gull, 

 or even of the inland nesting and inland feeding 

 black-headed gull. 



Recent investigation has added the yellow-browed 

 warbler, the blue-throat, and many other " rare," 

 or " casual " passerine birds to the list of regular 

 British birds of passage ; evidently they have 

 been overlooked before. Even the crossbill, so 

 long classed as a spasmodic invader, is now 

 seen to be a regular bird of passage to Britain, 

 though in varying numbers, and quite indepen- 

 dently of the sub-specific form which is always 

 with us. 



The wanderings to our islands of southern petrels 

 and other oceanic birds has occasioned much sur- 

 prise. Take two examples of the genus Oestrelata, 

 one 0. brevipes taken at Borth in 1889, and O. 

 neglecta in Cheshire in 1908, the known breeding 

 range of both being in the western Pacific ; pelagic 

 wanderings might lead a bird anywhere, but it is 

 conceivable that investigation may show that the 

 breeding area is wider than is supposed and that 

 these species have stations even in the South 

 Atlantic. 



