xii INTRODUCTION. 



[Fringilla cmlebs) and the Bullfinch {Pyrrhula vulgaris) are showy birds; 

 their mates are more sombre in appearance, and they build open nests, 

 where conspicuous or showy plumes would only .lead to their destruction. 

 The charming Stonechat {PratincoU rubicola), in his garb of chestnut, black 

 and white, is mated to a dull unassuming spouse, who derives her chief 

 safety during the' trying period of nidification from the dull and sombre 

 hues with whicli she is arrayed. Our second group consists of 



Birds in which the plumage of both sexes is showy or brilliant in 

 colour, and which nidificate in open nests.— This group forms one of 

 those exceptions which, at first sight, appears seriously to affect the validity 

 of the whole theory; but I think it can be shown that the birds included 

 in it may possibly secure their safety in other ways. It is unfair to suppose 

 that every species is equally liable to the attacks of enemies. Some gaily 

 attired female birds may have no special enemies against which to guard— 

 their brilliant or showy dress is no disadvantage to them, as is the case 

 with many conspicuous insects ; and this fact may in itself explain why it 

 is that they have assumed such tints. Again, as some female birds became 

 more brilliant through natural selection, it is very possible that they 

 gradually altered the form of their nests (from an open one to a covered 

 one), or if the acquisition of a showy dress did not render them more liable 

 to the attacks of any special enemy (and we know that many animals are 

 singularly free from persecution), no change in the manner of nesting 

 would be required ; and this would explain many of the apparent exceptions 

 to the general rule that gaily dressed female birds sit in covered nests. 

 We must also take into consideration what colours are showy in certain 

 haunts. Bright colours that would be very conspicuous in some places 

 may be specially protective in others. Take the case of the Tiger^s stripes, 

 conspicuous enough in the open or the green forest, but blending beauti- 

 fully with the jungle ; the light sand-coloured plumage of many desert- 

 birds would be conspicuous enough in fertile districts, but on the burning 

 sands it is invisible ; many other brightly plumaged birds are safe enough 

 in the localities where they build their nests or deposit their eggs; but 

 these facts are too often overlooked for want of careful investigation. 

 Again, and most important of all, the colour of the eggs in many cases 

 plays a prominent part ; for the moment danger threatens, the ever- watchful 

 and conspicuously coloured female quits her .charge and seeks her own safety 

 in flight, leaving her eggs or young to the safety which their tints insure. 

 In this group may be instanced the Orioles, represented in this country by 

 the Golden Oriole {Oriolus galbula). All these birds build open nests, the 

 sexes are almost alike in colour and of brilliant tints ; but they conceal 

 their nests amongst the thickest foliage, and, as Mr. Wallace states 

 protect their offspring by incessant anxious watching. 



To this group also belong the Jays, the Crows, the Birds of Prey, the 



