124 THE STORY OF BIRD-LIFE. 



weeding out would quickly begin. For they 

 would probably at once come in contact with 

 new creatures, who would rapidly discover how 

 good eggs were. Thus, those which were even 

 slightly coloured would be in so far disguised. 

 Having a taste for white eggs their enemies would 

 pass the coloured so long as white were to be 

 had. In this way white eggs would become more 

 and more rare, for in course of time the birds 

 which produced these would die, and die without 

 leaving offspring, or so few that they would be 

 swamped by inter-crossing with the newer and 

 more vigorous race who had succeeded in laying 

 coloured eggs. Some of these, unsuccessful in 

 producing coloured eggs, learnt the lesson of re- 

 peated robberies, and sought crevices in rocks, 

 or unoccupied burrows in the ground — them- 

 selves undertaking the work of excavating when 

 necessary — and they have survived, and their 

 children make their homes in holes in rocks and 

 burrows in the ground to this day. A process 

 precisely similar to that just sketched out was 

 going on at the same time in the forests. Eggs 

 here would soon have become a delicacy, and the 

 same mode of disguise almost certainly occur- 

 ring, the resultant protection would soon follow. 

 Those who failed to produce coloured eggs, and 

 yet survived, were those who sought safety in 

 the hollow trees always at hand. 



First of all, let us take a few cases of those 

 birds who lay their eggs in burrows and holes in 

 the ground, making little or no provision for them 

 in the shape of a nest. 



In the British Islands to begin with we have 



