BRITISH GENERAL MIGRATORY MOVEMENTS 



[T. A. COWARD] 

 I. INTRODUCTION 



SOME 190 species or subspecies of birds nest with regularity in the British Islands, but out 

 of the 470 or even more birds which have some claim to insertion in our avian catalogue, 

 no fewer than 116 are regular winter visitors or birds of passage. 1 This, so large a proportion 

 of the Palsearctic avifauna, justifies the contention that the British Islands are specially 

 attractive to migrants. The natural conclusion is that many birds select a coastwise in 

 preference to a purely overland route, that is, they prefer to travel along the western seaboard 

 of Scandinavia, and the western shores of Europe generally, rather than traverse the Continent 

 overland due north and south. Scotland and its islands, and the east and south of England, are 

 convenient resting-places for travellers to or from Western Scandinavia; South-eastern England 

 is little removed from the path of the great stream of birds which, journeying from Siberia, 

 Northern Russia, and Germany, makes use of the Baltic coasts, crosses the narrow neck of land 

 to the south of Denmark, passes near or over the world-famed ornithological " observatory " of 

 Heligoland, and, augmented by inland birds from northern Central Europe, coasts south- 

 ward along the south-western borders of the North Sea. 2 The bulk of these northern birds 

 are travelling in autumn southward along the Atlantic shores of France towards the Iberian 

 Peninsula and North Africa ; the route of some may be deflected eastward into the Mediterranean 

 basin. 



II. STUDY OF MIGRATION 



The general lines upon which the study of migration has been followed are, briefly, 

 as below : 



1. The recording of the first and, to a lesser degree, last dates upon which any particular 



1 In making this rough calculation no bird is counted twice ; the swallow, for instance, is considered as a 

 breeding species, as the passage form is not recognised as subspecifically distinct, Saunders, in the second edition 

 of his Manual (1899), gives the number of birds which had nested within the British Islands during the nine- 

 teenth century as 199. The evidence on which some were included is slender, and some were even then extinct 

 as nesting species. Others, like the ruff and bittern, have been reinstated, and some, such as the blueheaded- 

 wagtail, willow-titmouse, and blacknecked-grebe, have been added, whilst the insular races of birds, like the Irish 

 jay and coal-titmouse and the Shetland-wren, had not been recognised. Saunders treated 140 as more or less 

 infrequent, and 45 as regular non-breeding visitors. Opinions differ as to how many of the remaining 280 species 

 on our present list should be considered to be regular or irregular visitors, and some ornithologists maintain that 

 certain of them should not be included as British under any class. 



2 The assertion that there was a direct east to west and west to east fly -line between Heligoland and the shores 

 of Lincolnshire, founded on almost simultaneous observations of the grey-crow and other species by Gatke and Jolm 

 Cordeaux, was refuted by Mr. Eagle Clarke. Occasionally birds which have passed Heligoland may be drifted west- 

 ward so far as the southern English shores, but the direction of the main stream is normally south-west. 



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