174 THE ZOOLOGIST. 



for the eggs to be unnoticeable from below, the natural course 

 for the birds to take would be to build solid-bottomed nests 

 always. Nor has it yet been proved that a white egg is less 

 conspicuous from below than a coloured one. Mr. Beddard has 

 shown that white is not invisible from below, — that a snowflake, 

 when seen against a blue sky, looks black. If the colours of 

 eggs have any meaning, they are obviously a protection against 

 marauders above the nest. It is not usual for eggs laid in open 

 nests to be white, even when dense foliage overhangs them. The 

 eggs being white and the nest so flimsy, it might be supposed 

 that until recently these birds built in holes. But the fact that 

 by far the majority of the members of this great family {Columbiclce) 

 — which embraces some three hundred species— does not nest in 

 holes is a very strong argument against such a theory. These 

 birds lay but two eggs, and often begin to sit as soon as the first 

 egg is laid. In this way the need of colour would to some extent 

 be obviated. 



(c) Lastly, we must turn our attention to the Alcidce. The 

 eggs of the Common Guillemot display an extraordinary variety 

 in ground colour and markings. Dr. Wallace* and Mr. Dixon f 

 suppose that this is due to their being laid on inaccessible cliffs, 

 and thus completely protected from enemies. If this is the 

 correct explanation, it seems strange that the eggs should be 

 coloured at all. But a visit to Flamborough Head in the breeding 

 season will show that these eggs are not safe from all marauders. 

 These cliffs are tenanted by Jackdaws as well as by Guillemots. 

 And that the former have a taste for the eggs of the latter is 

 evident, for the shells of sucked eggs may be seen lying about on 

 the top of the cliffs. Prof. Poulton % believes that a more feasible 

 explanation is that all this variety of colouring enables " each 

 bird to know its own eggs." But, if this is necessary in the case 

 of Guillemots' eggs, how do Terns and Gulls, which nest together 

 in such dense numbers, dispense with a similar provision ? Most 

 of the eggs of any one species are very much alike, and are so 

 difficult to see that the greatest care must be taken by anyone 

 visiting their nesting stations in order to avoid treading on them. 



* ' Darwinism,' pp. 214, 215. 



f Seebohm's ' British Birds,' vol. ii. p. xxvii. 



I ' Colours of Animals,' p. 213. 



