CHAPTER XII 
COLORATION OF EGGS 
THE eggs of reptiles are white, and the reptilian 
origin of birds. would lead us to the conclusion that the 
eggs of primitive birds were like them. But the eggs 
of existing birds present a great variety of colours, 
though it is seldom that very bright tints are found, 
and the question is how these colours are to be 
accounted for. There can hardly be a doubt that 
the coloration is in some cases protective, but we 
must be careful not to extend this explanation too 
far. Dr. Wallace has pointed out that a very 
large proportion of the eggs that are white or light- 
coloured enough to be conspicuous are found in 
domed nests or nests built in holes, so that they 
cannot be seen. For instance, Kingfishers and Puffins 
nest in holes in the ground ; Woodpeckers, Hoopoes, 
and Owls in holes in trees; Wrens and the Willow- 
warblers build domed nests. Ducks and Grebes lay 
their pale eggs in open nests, but they have the habit 
of covering them up: these exceptions are, therefore, 
a very first-rate illustration of the principle. There 
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