CLASSIFICATION AND LIFE HISTORY 11 



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 frost was reported from every 

 district of England, Scotland and Wales. For three days in 

 the third week of April the thermometer registered from 10 

 to 27 degrees Fahrenheit. The Committee requested its local 

 correspondents to make careful observations on the resulting 

 damage, and the replies received brought to light several interest- 

 ing facts. In general it was stated that the effects of the frost 

 had been disastrous ; but when the evidence came to be analysed 

 the proof seemed strangely incomplete for very few reporters 

 were able to state from personal observations that eggs laid 

 before the frost had failed to hatch. On the other hand, several 

 accurate observers reported that they had marked down eggs 

 so frozen into the materials of the nest that it was not possible 

 to lift them out or to separate them from each other, yet it 

 was afterwards found . that these eggs hatched out healthy 

 chicks. On April 13th six Grouse eggs were found in a nest 

 amongst heather when the temperature was 25 degrees of 

 frost and all six hatched out. On another occasion, when it 

 happened that some Pheasant's eggs had been laid in a Grouse's 

 nest, the Pheasant's eggs were the eggs which failed, while 

 the Grouse's eggs were successfully hatched. Many observers 

 went so far as to say that unless the frost was sufficiently severe 

 to split the egg there was no danger of their fertility being 

 affected, and of all the gamekeepers to whom the question 

 was put very few could state that they had actually seen a 

 Grouse's egg split by frost. 



Actual splitting of the eggs by frost does occur, but it is 

 exceedingly rare when the nest is in its customary position 



