10 THE GROUSE IN HEALTH AND IN DISEASE 



of after-results, and certainly there is little doubt that the effect of a heavy 

 snowfall, while the birds are sitting, does not appear to produce the number of 

 unhatched clutches of weather-bleached eggs which might be expected. Some- 

 times, no doubt, matters reach the limit of endurance when, urged by the pangs 

 of hunger, the hen is forced to wander away in search of food and grit, and on 

 her return finds all trace of her nest buried beneath a smooth, white drift. 

 Even in this case all is not lost ; the snow fortunately does not lie long in the 

 months of April and May, and in due time she recovers her nest and resumes 

 her domestic duties. It is recorded that in 1908, on a Midlothian moor, 

 a heavy snowfall during laying-time covered the nests to a depth of 9 inches 

 for a period of ten days ; many eggs were lost, some even being laid on 

 the top of the snow ; in many cases the hen bird returned to her nest after 

 the snow had gone and laid more eggs beside those which had been covered 

 some of these birds hatched out every egg. Other cases have been reported 

 where the eggs were covered with snow for so long that their colouring 

 matter had disappeared, and yet they produced a healthy brood. 



From observations made upon Grouse in captivity it appears that during the 

 period of incubation the hen will often leave her nest for several days at a time, 

 for no apparent' reason, and will return again and hatch out the whole clutch 

 this power of absenting herself without disaster to her eggs must under 

 natural conditions stand her in good stead when the severity of the weather 

 Effects of makes the task of incubation unendurable ; but it is only in the earlier 

 part of the sitting season that her absence is unattended with risk, 

 for once circulation has commenced in the embryo chick the eggs must not 

 be allowed to become cold. Only when the hen is forced to leave the nest 

 on account of heavy rain is there a danger of her deserting the nest 

 permanently three days of incessant wet will suffice for this. 



Another danger to which the eggs of Grouse are liable is that of being 

 destroyed by frost while the hen bird is off the nest. This danger is greatest 

 Effects of during the period before the full clutch has been laid, for after incuba- 

 tion has commenced the hen will not readily leave her nest during 

 frosty weather for any length of time. Before the hen commences to sit she 

 will often cover up the eggs in the nest with twigs of heather, grass and 

 bracken, and this must save many of them from the effects of frost. 



The Committee has had an exceptionally good opportunity of studying the 

 effects of frost upon the eggs in the spring of 1908, when an extremely severe 



