24 THE GROUSE IN HEALTH AND IN DISEASE 



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 

 Reason for ^^ * u time of scarcity. Another theory is that, like many other 

 packing. ki r d g an d animals, the natural instinct of the Grouse is to congregate 

 in flocks, and that this instinct is only departed from to meet the requirements 

 of the breeding season. It is probable that various motives induce the birds to 

 congregate in packs. Some of these motives may be briefly mentioned, (a) To 

 get on to the high bare tops out of the wet it is observed that Grouse are always 

 more packed after wet weather. (b) To go down to feed on the cornfields ; Grouse 

 are seldom found feeding singly on the stocks ; this may be due to the natural 

 timidity of the wild bird, which makes it fear to resort to the unwonted feeding- 

 ground unless supported by numbers. The same rule applies with even greater 

 force to the case of birds leaving their own ground and wandering far afield in 

 search of food ; such migrations never take place except in large packs, (c) Owing 

 probably to the same cause, Grouse invariably tend to pack after they have 

 been much disturbed, especially by driving, on moors which for some reason 

 have not been shot over for a season ; the birds do not pack until late in the year. 

 (d) In dry weather small packs of two or three coveys are found at or near the 

 springs even on August 12th. 



Undoubtedly, the most common cause of packing is scarcity of food. It has 

 already been remarked that during the winter months the feeding area on every 

 moor is restricted to those parts where the heather is of such a character as 

 to resist the effects of frost and cold ; hence the birds tend to concentrate upon 

 these food centres. 



The habit of packing is probably indirectly connected with the question 

 of disease. If we admit that the congestion of a large number of birds upon 

 small areas of moor is conducive to the deposit in dangerous numbers of 

 the larval worms which cause disease on the favourite feeding - grounds of 

 the birds, then it follows that the pack formation is in itself a danger to the 

 health of the stock. This view is supported by the fact that where packing 

 is the exception rather than the rule, as in the west coast of Scotland, disease 



