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. Sometimes, 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 weatherEffects of
wet. 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
frost. during the period before the full clutch has been laid, for after incubation 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
