43 



MIGRATION. 



Emigration 

 of Wood- 

 cocks. 



Kange of 

 < omuion 

 Woodcock. 



American 

 Woodcock. 



OtherWood- 

 cocks. 



doubt that it is only one of many others, by means of which the present geographical 

 distribution of birds can alone be explained. 



As a typical example of emigration we may take the journeys which the ancestors of 

 the nearest allies of the Woodcock (Scolopax rusticola) must have made in order to have 

 become distributed as they now are. This bird is very closely allied to three other species. 

 These four Snipes differ from all other species of the genus in having the under surface of 

 the tail-feathers tipped with silvery white, and in having the dark bands on the crown 

 transverse instead of longitudinal. It is not known that they differ structurally from the 

 other species of Scolopax in any way ; but two peculiarities of colour so marked are a 

 coincidence too extraordinary to have been separately acquired by each of the four species, 

 and may be accepted as a proof of a comparatively recent common origin. The 

 Common Woodcock, being the most numerous species, having the widest range and 

 occupying the central position geographically, may fairly be regarded as representing the 

 least changed descendants of the common ancestors, and as inhabiting the original area of 

 distribution. This may be described as a belt of land extending across Europe and Asia, 

 from England to Japan, only reaching the Arctic Circle in Scandinavia, and only 

 extending to the southern parts of the Palrearctic Region, where high elevations on the 

 Alps, the Caucasus, or the Himalayas reduce the mean temperature during the breeding- 

 season to a moderate figure. 



The American Woodcock (Scolopax minor) breeds in a somewhat similar temperature 

 on the American continent. The ancestors of this species must either have crossed the 

 Atlantic or reached America by way of Behring Straits. As the present range of the 

 American Woodcock only extends about halfway across the continent, and is confined to 

 the Atlantic half, we may dismiss the Behring-Sea route as inadmissible ; and we may 

 regard the theory that the emigrants crossed the Atlantic as placed beyond doubt, since 

 we learn that the Common Woodcock is still found on the Azores, and accidentally wanders 

 to America, where it has been recorded from Newfoundland, New Jersey, and Virginia. The 

 distance from the Azores to the nearest point of Europe is at least a thousand miles, and from 

 those islands to Newfoundland considerably more. The fact that Woodcocks occasionally 

 make these journeys proves that the feat is by no means impossible. The other two species 

 so nearly allied to our Woodcock are probably the descendants of emigrants from Japan. 

 The Moluccan Woodcock (Scolopax rochusseni) is a resident in the Molucca Islands; and 

 Horsfield's Woodcock (Scolopax salurata) is only known from Java and Western New 

 Guinea. These localities are easily reached without any difficulty. 



It is not necessary to give further details of the emigration of other Limicoline birds, 

 as the subject will be more fully treated of in the following chapters, and an attempt 

 will be made to show the chief lines of emigration followed by the ancestors of each 

 genus. 



Hitherto we have spoken of emigration as an exceptional event, occurring at a long 

 interval of time from a similar exodus, and produced by exceptional causes, such as a glacial 



