SOME BIRDS OF THE WINTER. 321 



and back to the Swedish woods and fells they go 

 with the spring. I am strongly of opinion that 

 these birds require a certain temperature in which 

 to rear their young, and return each season to 

 districts where such prevails. The Snow Bunting 

 is a remarkable instance of this. In Scotland 

 this bird finds the ground or sea-level tempera- 

 ture of the Arctic regions on the tops of the 

 Grampians, and a few consequently remain 

 behind to breed there. Numerous other instances 

 might be given of northern species breeding in 

 the south on high mountains, where the tempera- 

 ture is the same as that enjoyed in their usual 

 habitat. 



Though more strictly speaking a stranger of 

 the spring, Pallas's Sand Grouse may still be not 

 inaptly noticed in the present chapter. This 

 bird wanders about a good deal in winter like the 

 rest of the gipsy migrants, and appears to have 

 no very regular migrations or true winter home. 

 It is a bird of the steppes of Central Asia, and 

 from time to time invades Europe in considerable 

 " rushes." The last important visitation to the 

 British Islands was in the spring of 1888; but 

 it is more than doubtful whether this species will 

 ever become naturalised in this country, in spite 

 of the protection extended to it. It may readily 

 be distinguished from all other British birds by its 

 feathered legs and toes, the absence of a hind toe, 

 and the pointed first primary and two centre tail 

 feathers. 



