212 BIRDS OF NORTHERN TIBET. 



disappears instantaneously, either by taking to flight 

 or by crouching on the ground, a manoeuvre frequently 

 practised during the breeding season, which lasts from 

 the end of January to the end of February. During 

 this time their hideous cry may be heard night and 

 morning, closely resembling the hooting of an owl. 

 The corsac lives in burrows of its own construction. 

 The Mongols and Tangutans catch it by setting traps 

 at the entrances of these holes. 



Turning from the mammalia of Northern Tibet 

 to the birds, we find a general deficiency of the lat- 

 ter. It was, to be sure, mid-winter when we were 

 there, and the summer birds had all flown away ; but 

 at the best of times no great variety can be expected 

 in this country, so variable and unfavourable are its 

 physical conditions. During our two and a half 

 months' stay here we saw but twenty-nine kinds, 

 only one of which {Cinclus sp.) was new ; the others 

 we had seen in Kan-su and Koko-nor. The few we 

 saw in Northern Tibet were mostly on the border, 

 north of the Shuga, and between this river and the 

 Murui-ussu they were very scarce. 



The most common birds of Northern Tibet are : 

 vultures ( Vulhtr mojtacJms, Gyps nivicola), lammer- 

 geiers {Gypa'dtos barbatus), and crows {Corvus cor ax) ^ 

 all which appear as soon as an animal is slain ; red- 

 legged crows [Fregilus gramhis), which collect in 

 vast flocks during winter ; sandgrouse {Syrr/iaptes 

 Tibetamis), larks {Melanocoiypha maxima, Alaiida 

 albigula), linnets {Linota brevirostra), the last named 

 probably only wintering here ; also the Podoccs /m- 



