OBSERVATIONS ON THE FOOD OF GROUSE 81 



in a far greater proportion. No doubt the necessity for provision during 

 the longer hours of night-time has some effect in the overfilling of the crop 

 in winter, but this would not account for crops being heavier in March, 

 when the days are comparatively long, than in November when they are short. 



The interesting fact remains, and is amply proved by the figures, that 

 more food is required by the Grouse in winter than in other seasons of the 

 year ; and as in winter the proportion of Calluna to all other foods is as 

 seven to one, it is obvious that a very great advantage accrues to a Grouse 

 on a moor in which young and comparatively nourishing heather is abundant 

 during the winter months, i.e., on a well-burned moor, well covered with 

 young heather of a varying number of seasons' growth. 



To put this conclusion in other words ; whereas in summer a certain area 

 of heather will support a bird comfortably, many times this area will be 

 required for the same bird in the winter, so that the capacity of a moor, as 

 regards the question of stock, must be gauged mainly by its Grouse-feeding 

 value during the winter months. 



If we consider this generalisation with reference to moor management we 

 shall see that a moor carrying its full tale of birds in the summer becomes 

 automatically and unavoidably overstocked in the winter unless the stock is 

 heavily reduced by shooting, for not only is there less food available, but 

 the birds require a much larger quantity of food to keep them in health. 



Migration of birds in winter obviously complicates the question. In the 

 case of a moor on high ground, which often loses all its birds in winter, 

 probably natural conditions regulate the stock of birds automatically Effect of 

 during spring and summer. But on the adjacent low-lying moors mi s ratlon - 

 the case is more serious ; for the ground has to supply not only more food 

 than is needed for its own stock in summer, but in addition an increased 

 seasonal demand made upon it during the winter months by hundreds of 

 undesirable immigrants from the higher ground. Such low-lying moors must 

 always run the risk of being dangerously overstocked in the winter. 



In certain parts of the country oats form a regular seasonal change in the 

 dietary of Grouse, and this form of food must now be considered. 1 



Very few birds with corn in any part of the alimentary canal were 

 submitted for examination ; but so far as these specimens show, oats are an 

 unsuitable form of food for Grouse. As is well known, Grouse often visit the 



1 Vide also chap i. p. 25, and chap. viii. pp. 178-180. 

 VOL. I. F 



