190 



THE VICTORIAN NATURALIST. 



Mr. Wallace's views that the colours were acquired by the male> 

 and being transmitted to the female, were not eliminated by- 

 natural selection owing to the protection which they already 

 enjoyed from the manner of their nidification, he says : — " It seems, 

 to me much more probable that in most cases, as the females were 

 gradually rendered more and more brilliant from partaking the 

 colours of the male, they were gradually led to change their 

 instincts (supposing that they originally built open nests), and to 

 seek protection by building concealed nests." And further — " It 

 is not necessary to suppose that each species has had its nidifying 

 instincts modified, but only that the early progenitors of each 

 group were led to build domed or concealed nests, and that thus, 

 sexua.l selection, together with equal or nearly equal inheritance 

 by both sexes, has indirectly determined the manner of nidifica- 

 tion of whole groups of birds." 



I have quoted Darwin's opinions at length, in order to show 

 that this system of natural selection going on with the birds, 

 sends them to the hollows and other concealed situations to 

 build, and so affects the colouring of the eggs as it operates- 

 to modify the colours of the birds themselves, and this I 

 will attempt to prove ; but in the first place I will now state 

 definitely the rules which I think govern egg colourations. 

 These are : Firstly — Eggs laid in dark situations, or by nocturnal 

 birds, are white. Secondly — Eggs laid on the bare ground, or in 

 other similarly exposed situations, are very frequently coloured se- 

 as to resemble surrounding objects. Thirdly — Eggs laid in open 

 nests are very often, though by no means invariably, beautifully 

 and cons]Dicuously coloured. 



With regard to the first division, those laying white eggs — 

 firstly, nocturnal birds — for example, the owls of Europe, Canada,. 

 India, and Australia, and the podargi of the latter country, all, 

 without exception, lay white eggs, and as some of these— for 

 instance, the podargi — do not build in hollows, I think that they 

 form a distinct section. Secondly, of those laying in holes, in- 

 trees, or in the ground, the large families of kingfishers, 

 parrots, and woodpeckers, also the following : — Tree-creepers 

 ( Certhiada). some species only; bee-eaters /^J/.?/-^/^//?'^^, petrels (all 

 lay white eggs, some in holes in the ground), rollers ( Coracidce),. 

 and diamond birds ( Pardalotus ) may be taken as examples. 

 The swallows also furnish us with good illustrations of this rule,, 

 for those species which build saucer nests exposed to the light 

 lay eggs more or less coloured with reddish brown, whilst those 

 building in holes, such us our tree swallows ( Hylochdidon 

 nigricans ) . or far down chimneys, such as the rufus swallow of 

 Europe, lay perfectly white eggs. A seeming exception is found in 

 some genera of the Certhiadai, for if we look at the egg of our own 

 common tree-creeper ( Cliviacteris scandens), which builds its nest 



