162 Wonders of the Bird World 



depositing them on the bare floor of a chamber at the end 

 of a tunnel which they excavate themselves, or laying them 

 on the chips of wood which result from the hewing of the hole 

 which they bore in a tree-trunk or branch. Woodpeckers 

 especially adopt this mode of nesting, as do their cousins 

 the Barbets (Capitones), and one reason for the placing of 

 the eggs in concealment has often been suggested, viz. 

 that the latter being white and very conspicuous, would fall 

 an easy prey to some prowling bird or lizard, if they were 

 placed in an open nest and exposed to view. Of the truth 

 of this surmise there can be no doubt, and that the 

 majority of birds which lay white eggs are at pains to 

 conceal them is an evident fact, but certain exceptions 

 will doubtless occur to the mind of the reader, as, for 

 instance, in the case of the Nightjars (Caprimulgi), which 

 are always considered to be truly Picarian Birds, and 

 which ought, therefore, to lay white eggs in a hole of a 

 tree, but do not do so. On the contrary, they lay two eggs 

 on the ground, and these are not white, but are marbled 

 with grey, so they are not easy to discover. Pigeons, too, 

 lay white eggs in an open nest, and these must be plainly 

 visible from above, while, on the other hand, Tits, Creepers, 

 and Nuthatches, which usually lay spotted eggs, conceal 

 them with as much care as if they were white ones, in the 

 hole of a wall or in a bag-shaped nest like that of the Long- 

 tailed Tit {s&githalus vagans) or the Wren (Anorthura 

 troglodytes). 



The most variable egg in the world is probably that of 

 the Common Cuckoo {Cuculus canorus), as it is also 

 probably the smallest in proportion to the size of the bird, 

 but for this there is apparently good reason, for among all 

 the members of the Class Aves, there is no more wonder- 

 ful bird than our Cuckoo, which is more fully noticed 

 under the heading of the Parasitic Birds (p. 295). But 

 while our well-known species places its egg in the nest of 



