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BIRDS' NESTS AND EGGS. 

 By Henry Seebohm. 



The philosophy of birds' nests and eggs involves questions 

 far too profound to be settled in an hour's lecture. The extreme 

 partisans of one school regard birds as organic automata. They 

 take a Calvinistic view of bird-life : they assume that the Hedge- 

 sparrow lays a blue egg because, under the stern law of protective 

 selection, every Hedge-sparrow's egg that was not blue was tried 

 in the high court of Evolution, under the clause relative to the 

 survival of the fittest, and condemned, a hungry Magpie or Crow 

 being the executioner. The extreme partisans of the other school 

 take an entirely opposite view. They regard the little Hedge- 

 sparrow, not only as a free agent, but as a highly intelligent one, 

 who lays blue eggs because the inherited experience of many 

 generations has convinced her that, everything considered, blue 

 is the most suitable colour for eggs. 



Perhaps the first generalisation that the egg-collector is likely 

 to make is the fact that birds that breed in holes lay white eggs. 

 The Sand Martin and the Kingfisher, which lay their eggs at the 

 end of a long burrow in a bank, as well as the Owl and the 

 Woodpecker, which bred in holes in trees, all lay white eggs. 

 The fact of the eggs being white, and consequently very con- 

 spicuous, may have been the cause, the efi'ect being that only 

 those Kingfishers which breed in holes survived in the struggle 

 for existence against the marauding Magpie. But the converse 

 argument is equally intelligible. The fact that Kingfishers breed 

 in holes may have been the cause, and the whiteness of the eggs 

 the effect ; for why should Nature, who is generally so economical, 

 waste her colouring-matter on an egg which, being incubated in 

 the dark, can never be seen ? The fact that many Petrels and 

 most Puffins, which breed in holes, have traces of spots on their 

 eggs, while their relations the Auks and the Gulls, who lay their 

 eggs in open nests, nearly all lay highly-coloured eggs, suggests 

 the theory that the former birds have comparatively recently 

 adopted the habit of breeding in holes, and that consequently 

 the colour being no longer of use is gradually fading away. 

 Hence, we assume that the colour of the egg is probably the 

 effect of the nature of the locality in which it is laid. 



ZOOLOGIST. — APRIL, 1887. M 



