THE LIFE HISTORY OF THE GROUSE 23 



of Trichostrongylus as the lower moors which were crowded with Grouse 

 throughout the winter. The melting of the snow may also have the effect of 

 washing the Strongyle larvae out of the heather. 



If the birds are well matured by August 12th they often begin to "pack" 

 after the first few days' shooting, and will not then readily lie to dogs. Packing 

 may at times take place so early as to make shooting over dogs an 

 impossibility. On this account the poor results formerly obtained on 

 most English moors led to the introduction of "driving." In Caithness and 

 eome other districts the Grouse, being more backward, do not pack except under 

 exceptional conditions. 



This custom of packing is worthy of study, for it may be found to have 

 a direct bearing upon the questions of disease, migration, interbreeding, and 

 the preservation of the stock. 



In the first place, it may be stated that it is the young birds rather than 

 the old birds that tend to form into packs in the earlier months of autumn, 

 though the older birds will follow suit as the winter advances. Consequently, 

 when packing first begins, it is the older birds that suffer the greatest loss in 

 a 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 intro- 

 duction 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 the autumn and winter months, and the more 

 severe the weather the more marked is the tendency of the birds to form 

 into large companies and flocks. 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. 



