40 NATURAL HISTORY OF THE GROUSE 



but that under certain conditions the majority of 

 English grouse desert their favourite moors for a short 

 period in order to satisfy the pangs of hunger. The 

 question whether grouse are liable to migrate in 

 the early spring, when food is apparently plentiful, 

 suggests a more difficult problem. There are good 

 sportsmen, at any rate, and careful field naturalists 

 who incline to believe that the grouse, like its distant 

 relative Pallas's sand grouse, is occasionally seized 

 by paroxysms of migratory fever, under the influence 

 of which the birds travel for many miles from their 

 home moor. But positive proof that this is so is 

 still wanting, and the question can only be settled 

 by means of marked birds. 



