Birds of Northern Tibet. 243 



lumba rupestris) — is found ; the Gallinaceous birds are repre- 

 sented by two species^ the Tibetan Giant Partridge {Mega- 

 loperdioc tihetanus) and the Tibetan Three-toed Sand-Grouse 

 {Syrrhaptes tibetanus), and of the Waders and Swimmers we 

 only saw a few autumnal migrants on passage. 



This poverty of the ornis is easily explained by the extreme 

 unfitness of the physical and geographical features of the 

 country for bird-life. There are neither trees nor bushes 

 upon the seeds of which birds could feed and in which they 

 could nest ; the mostly saline lakes have no fish ; the banks 

 of the rivers are uniformly open and bare ; and the moun- 

 tains have few rocks for the alpine birds to resort to. No 

 wonder therefore that over the great expanse which we 

 traversed we found only nineteen species of resident birds^ 

 and the list would hardly be doubled if the whole remaining 

 portion of Northern Tibet westwards to the Karakorum 

 were explored. Even the migrants hasten to traverse 

 Northern Tibet without halting, and only a few Eaptores 

 linger a little time in the autumn, allured by the number- 

 less Pikas {Lagomys ladacensis), which offer them a ready 

 sustenance. But even this circumstance^ which usually plays 

 an important part in the selection of a winter home, cannot 

 induce our Raptores to stay through the winter; for the 

 greater number of them hasten further south to the Brah- 

 maputra valley, or perhaps even across the Himalayas. Only 

 three species remain, Archibuteo aquilinus, A. stropliiatus, 

 and Falco sacer, and of these, too, but a very restricted 

 number of individuals. 



Large Waders, such as Cranes {Grus cinerea and G. virgo), 

 traverse Northern Tibet in enormous flocks in autumn with- 

 out halting ; at the same season water-fowl also pass over. 

 The Passeres, especially those that frequent woods, appa- 

 rently perform the transit by some more eastern route and 

 avoid the high ranges. During the whole of the later autumn 

 (after Sept. 20th) we saw only twenty -nine species of Pas seres. 

 In spring the migration is, most probably, still more reduced 

 in numbers, because the spring season is still more inclement 

 than the autumn. In summer certainly only the resident 



