i88s.] Allen on Sexudt Selection and the Nesting of Birds. T 3 3 



ceptions to the rule being very rare; for to the above groups 



must be added the hundreds of species of Passerine birds which 

 build a domed nest, as the Malurhie birds, the Weaver Birds, 

 the Munias, the Willow-warblers, the Sunbirds, the Pittas, the 

 Tailor Birds, the great Synallaxinine series, and many others. 

 In all these cases the eggs as a rule are pure white, and when 

 deviating from this are simply pale bluish white, or white with 

 a few minute specks, or lustrous white speckled with reddish, in 

 in such a way as in nowise to render the eggs less conspicuous 

 than if pure white. Mr. Dixon, in his paper now under notice, 

 has called attention to the same facts, and commenting on this 

 coincidence says, "This law is almost universal.- 1 



If we pass to water birds, we find many of the Petrels nesting 

 in holes and laying white eggs ; and that the Ducks and Grebes 

 lav white or nearly white eggs, and. though building an open 

 nest, cover them on leaving them : and. it may be added, the same 

 is true of many Pheasants and Partridges. 



There are. on the other hand, birds which lay white eggs in an 

 open nest, but the number Is few in comparison with those which 

 lay white eggs in nests affording concealment, or colored eggs in 

 open nests. Again, some eggs laid in open nests are intensely 

 white in ground-color, with markings which tend to make them 

 more conspicuous rather than contribute to concealment. Such 

 are the eggs of most of the gnat group of Tyrant Flycatchers ot 

 America. Of species laving white eggs in open nests, the 

 Pigeons and the Hummingbirds are prominent examples, embrac- 

 ing as they do a multitude of species. To this list may be added 

 a few ground-nesting Hawks and Owls which lay white, or at 

 least whitish, eggs, and the Herons, Storks, Pelicans, and Cor- 

 morants. In respect to these exceptions, it may be said that the 

 Tyrant Flvcatchers are especially watchful of their nests and 

 courageous in their defense, and succeed in driving away even 

 predacious birds greatly exceeding them in size. The Pigeons 

 and some Goatsuckers, as Mr. Dixon suggests, build a very 



* He adds, however, as a part of the same sentence, "and, curiously enough, white 

 eggs are correlated to a great extent with the brilliant plumage of the bird; for we 

 have already seen how so many of these showy birds breed in covered nests." This 

 latter fact, however, loses much of its significance when we remember that nearly as 

 many other birds of equally brilliant plumage lay colored eggs in open nests, and also 

 that nearly as many dull-colored birds as bright-colored ones lay -white eggs in nests 

 which afford them concealment. 



