CLASSIFICATION AND LIFE HISTORY 27 



day's Grouse driving, for they come up to the line of butts 

 in twos and threes, and are " mopped up " to a bird, whereas 

 the larger packs of younger birds merely yield a percentage 

 of their numbers to swell the bag. To this cause may perhaps 

 be ascribed some of the beneficial results which attend the 

 introduction of driving on many moors. 



Another important fact connected with packing is the 

 tendency of the stock to separate into sexes there are hen 

 packs and cock packs, or at least each pack contains a large 

 majority of one sex. It has been noted that certain hills in 

 a range of moorland are frequented by hen packs, others by 

 cock packs. 



The normal time for packing is in the autumn and winter 

 months, and the more severe the weather the more marked 

 is the tendency. Hens pack more readily than cocks ; the old 

 cock does not appear to be of a sociable disposition, and often 

 throughout the winter he will remain in solitary state, and 

 only join the pack temporarily during a period of unusual 

 storm. This tendency is often taken advantage of by those 

 moor-owners who regard the old cocks as a menace to the 

 health of their stock, and on many well-managed moors a 

 rigorous crusade is carried on against the old single birds that 

 frequent the bare tops, while their younger relatives occupy 

 the lower ridges. 



During the winter months the advent of mild weather 

 will often break up the packs for a while, and many cases have 

 been reported of birds being scattered over the moor in pairs 

 even in the months of November, December, and January ; but 

 with the return of wintry conditions their gregarious habits assert 

 themselves even up to the commencement of the nesting season. 



The reason why Grouse 'should pack in winter has often 

 been discussed. The most favourite explanation is that they 

 combine with a view to obtaining food in time of scarcity. 

 Another theory is that, like many other birds and animals, 

 the natural instinct of the Grouse is to congregate in flocks, 

 and that this instinct is only departed from to meet the require- 



