BIRDS 



small flocks of immature black-headed gulls, a few golden-plover, and occa- 

 sionally a few redshanks, may still linger on. The only important bird of 

 passage is the whimbrel, which in some years is very plentiful. Occasional 

 knots and wood-sandpipers are also seen, and of late years a flight of black 

 terns may linger in the west. The latest incoming birds at this season of the 

 year are swallows, flocks of which have been recorded on the south coast, not 

 only in the latter part of May, but as late as 9 June. These are probably on 

 their way to nesting sites on the northern limit of their breeding area. 



Recent investigation has shown that land birds on migration avoid high- 

 lying ground, adhere more or less closely to well-defined routes, often skirt the 

 general shore-line for great distances, enter the land at regular openings on the 

 coast, and when passing overland usually follow the direction of river valleys. 

 The usual routes or flight lines of Cornish birds on migration appear to be 

 somewhat complex. In the great autumnal invasion from the north-east 

 many birds undoubtedly come into the county from Devon, but there is at 

 the same time an important flight-line down the coast of the Bristol Channel. 

 Systematic notes for the north coast, however, are still unfortunately somewhat 

 scanty. 



The county lies too far away to participate in the great east-to-west 

 rushes from the Continent that are so conspicuous a feature during the autumn 

 months in the eastern counties, and consequently there is an absence of 

 several east-coast casuals and vagrants, such as the blue-throated warbler, the 

 barred-warbler, the icterine-warbler, Pallas's warbler and the great spotted 

 cuckoo. Still it receives considerable accessions from birds that are migrating 

 down the Channel both along the English and French coasts, and it seems 

 probable that many of our casuals, as well as birds of a higher status from 

 northern and central Europe, come to us, not across England, but along the 

 western shores of the Continent. Both in the Channel and beyond it birds 

 on autumn migration at times encounter heavy gales, particularly from the 

 south-west, and are driven back on to the Isles of Scilly and the Cornish main- 

 land, and especially into that great bay that stretches from Land's End to 

 the Lizard. Most of the birds so driven on to our shores in the autumn 

 are resident species, summer migrants and birds of passage in Cornwall, 

 and cannot as a rule be distinguished from those belonging to the county, 

 except when waifs and strays of an exceptional character are associated with 

 them. It is probably due to the disturbance of coastal migration down the 

 west of the European mainland by adverse weather, that we receive the fire- 

 crest practically every autumn or winter. The occurrence of such vagrants 

 at Scilly as the yellow-browed warbler, lesser-shrike, woodchat, ortolan- 

 bunting, short-toed lark, little ringed-plover, tawny-pipit and red-breasted 

 flycatcher, as well as of various unexpected accidental visitors on the south 

 coast of the Cornish mainland as far east as St. Austell Bay is evidently due 

 to the same cause. 



A remarkable feature among accidental visitors in the autumn and winter 

 to the western half of the county is that no less than eighteen of the species 

 are American. It is difficult to believe that these birds, with the possible 

 exception of one or two individual cases of ' assisted passage,' could have come 

 across the Atlantic. The usual explanation of the presence of such species 

 in Western Europe is that the birds lose their way in the far north, and 



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