Chap. XVI. Birds — Colour and Proixtion. 489 



for no instaiiRe is known, as far as I can discover, of the young 

 of duU-uoloured species displaying bright colours, or of the young 

 of bright-cokmred species being more briMiant tJian their parents 

 la the fourth class, however, in which the young and the old 

 resemble each other, there are many species (though by no 

 means all), of which the young are bright-coloured^ and as those 

 form whole groups, we may infer that their early progenitorB 

 were likewise briglit. AWith this exception, if we look to tho 

 birds of the world, it appears that their beauty has been much 

 increased since that period, of which their immature plumage 

 gives us a partial record. 



On the Colour of the Plumage in rdution I0 Fro/ection. — It will 

 have been seen that I cannot follow Mr. Wallace in the belief 

 that dull colours, when confined to the females, have been in 

 most cases specially gained for the sake of protection. There 

 can, however, be no doubt, as formerly remarked, that both 

 sexes of many birds have had their colours modified, so as to 

 escape the notice of their enemies ; or in some instances, so as to 

 approach their prey unobserved, just as owls have had their 

 plumage rendered soft, that their flight may not be over- 

 heard. Mr. Wallace remarks *' that " it is only in the tropics, 

 " among forests which never lose their foliage, that we find 

 " whole groups of birds, whose chief colour is green." It will be 

 admitted by every one, who has ever tried, how difficult it is to 

 distinguish parrots in a leaf-covered tree. Nevertheless, we 

 must remember that many parrots are ornamented with crimson, 

 blue, and orange tints, which can hardly be protective. Wood- 

 peckers are eminently arboreal, but besides green species, there 

 are many black, and black-and-white kinds — all the species 

 being apparently exposed to nearly the same dangers. It is 

 therefore probable that with tree-haunting birds, strongly-pro- 

 nounced colours have been acquired through sexual selection, 

 but that a green tint has been acquired oftener than any other, 

 from the additional advantage of protection. 



In regard to birds which live on the ground, every one admits 

 that tliey are coloured so as to imitate the surrounding surface 

 How diiflcult it is to see a partridge, snipe, woodcock, certain 

 plovers, larks, and night-jars when crouched on ground. Animals 

 inhabiting deserts offer the most striking cases, for the bare 

 surface affords no concealment, and nearly all the smaller quad- 

 rupeds, reptiles, and birds depend for safety on their colours. 

 Mr. Tristram has remarked in regard to the inhabitants of tht 

 Sahara, that all are protected by their "isabelline or sa);d- 



« ' Westminster Review,' July, 1867, p. 5. 



