io6 THE MIGRATION OF BIRDS. 



unknown in the north-west of that country. It 

 swarms in the adjoining valley of the Yangtse, 

 which is a continuation of its fly-line to the northern 

 summer haunts. Again, it is apparently by this 

 route that many rare Eastern stragglers to India 

 enter that empire and follow the Ganges. The 

 Crested Teal [Anas falcatd) and the Baikal Teal 

 i^Anas formosa) may be mentioned as instances, 

 both of which species are common winter visitors to 

 the Yangtse. Other important Asiatic river routes 

 are along the Ganges, the Indus, and the Oxus, 

 forming the great valley passages into India from 

 the north-west ; and the Tigris and Euphrates, 

 which assist the passage of birds breeding in 

 Europe and wintering in Asia. Instances of the 

 latter, however, are rare. The two most interesting 

 are perhaps the Rose-coloured ^diStox [P astor roseiis) 

 and the Black-headed Bunting [Emberiza melanoce- 

 pliala)^ which visit South Europe as far west as 

 Italy in summer, and are only known to wdnter in 

 India. The great water-ways of North America, 

 stretching as they do directly and almost con- 

 tinuouslv from Alaska to Mexico, are also routes 

 of migration of the highest importance, seeing that 

 coast routes can only be followed by a very small 

 percentage of the birds visiting an area in which 

 the two coasts are nearly 3000 miles apart. To a 

 very great extent migration from the North-west 

 follows the Mackenzie River, and the various water- 

 ways that lead to the largest lake system on the 

 earth's surface ; and doubtless a good deal of coast 



