68 THE MIGRATION OF BIRDS 



larger bird appears, the Greenland wheatear, Saxicola 

 oenanthe leucorrhoa, which was recognised in Green- 

 land, Iceland and eastern North America before it 

 was seen that both forms occurred in Britain. This 

 larger bird loiters through Britain, for its northern 

 home is not ready for it until the Arctic spring. We 

 know it breeds farther north than our wheatear, 

 but its winter range is not fully worked out. The 

 smaller bird is found in north and north-western 

 Africa, and the larger form farther east, even south 

 of the equator on the eastern seaboard, and probably, 

 when we know more about the range of the two we 

 shall find that the form breeding farther north, 

 winters farther south. 



The folly of laying down the law on the strength 

 of the knowledge of the habits of a few species is 

 show r n by the study of the movements of American 

 birds. Mr Cooke shows that as a rule " the migra- 

 tion is a synchronous southward movement of the 

 whole species " in autumn, " the different groups of 

 individuals or colonies retaining in general their 

 relative position/ 3 The black and white creeper 

 Mnistitta varia breeds from South Carolina to New 

 Brunswick, nesting in the south in April and reach- 

 ing the northern limits in the middle of May. In 

 the middle of July old and young birds have been 

 seen at Key West, 500 miles south of the breeding 

 range, and towards the end of August they have 



