THE FOOD OF THE RED GROUSE 81 



but that full crops are more commonly found in birds killed 

 in the afternoon and evening, both in winter and summer, 

 than in the morning and forenoon. 



When a Grouse is in health the gizzard invariably contains 

 food undergoing a grinding process throughout the hours of 

 daylight, even in the longest summer day. The crop is often 

 found very full towards evening, and rarely so before noon ; 

 but this is only because in the evening the bird feeds more 

 heavily in order to store up food for the hours of darkness, 

 while during the daytime he seldom eats more than the digestive 

 processes can deal with at the time. Hence during the early 

 part of the day the food passes rapidly from the crop to the 

 gizzard and on to the digesting tracts of the gut proper, and 

 the crop is left almost empty. This has given rise to the view 

 that Grouse only feed once a day, and that in the evening. 



Heather (Calluna vulgaris), as is well known, is the ordinary 

 food of the adult Red Grouse. But twenty or thirty other 

 plants are also eaten, often in great quantities, and it is a well 

 ascertained fact that Grouse that have never set eyes upon 

 a sprig of heather will live and flourish for years. 



Yet the importance of heather in building up the birds 

 for the approach of winter cannot be exaggerated, and there 

 is little doubt that in a bad heather year all the young birds 

 suffer, while even in a good heather year the later broods will 

 be permanently handicapped as regards physique and disease- 

 resisting power if they have missed the best food months. 



The most noteworthy fact brought out by Table I. is that 

 Grouse appear to require a larger quantity of food in the winter 

 months from December to March, than in the spring, summer 

 and autumn months from April to November. 1 



It is, of course, true that in a bad heather year Grouse may 

 find substitutes for their staple diet. Of these substitutes 

 blaeberry is undoubtedly the most valuable, as may be seen by 

 reference to Tables II. and III. ; 2 but in many districts blae- 

 berry does not grow upon the moors, and in no case is it so 



1 Vide also p. 34. 2 yid,e pp. 82 and 89. 



F 



