COLOURS OF ANIMALS 



comparatively rare and not great in amount, whereas among 

 birds they are very frequent and very largely developed. So 

 among insects, they are abundant in butterflies, while they are 

 comparatively uncommon in beetles, wasps, and hemiptera. 



The phenomena of sexual variations of colour, as well as of 

 colour generally, are wonderfully similar in the two analogous 

 yet totally unrelated groups of birds and butterflies ; and as 

 they both offer ample materials, we shall confine our study of 

 the subject chiefly to them. The most common case of differ- 

 ence of colour between the sexes is for the male to have the 

 same general hue as the females, but deeper and more intensi- 

 fied as in many thrushes, finches, and hawks, and among 

 butterflies in the majority of our British species. In cases 

 where the male is smaller the intensification of colour is 

 especially well pronounced as in many of the hawks and 

 falcons, and in most butterflies and moths in which the 

 coloration does not materially differ. In another extensive 

 series we have spots or patches of vivid colour in the male, 

 which are represented in the female by far less brilliant tints 

 or are altogether wanting as exemplified in the gold-crest 

 warbler, the green woodpecker, and most of the orange-tip 

 butterflies (Anthocharis). Proceeding with our survey, we 

 find greater and greater differences of colour in the sexes, till 

 we arrive at such extreme cases as some of the pheasants, the 

 chatterers, tanagers, and birds-of-paradise, in which the male 

 is adorned with the most gorgeous and vivid colours, while 

 the female is usually dull brown, or olive green, and often 

 shows no approximation whatever to the varied tints of her 

 partner. Similar phenomena occur among butterflies ; and in 

 both these groups there are also a considerable number of 

 cases in which both sexes are highly but differently coloured. 

 Thus many woodpeckers have the head in the male red, in 

 the female yellow ; while some parrots have red spots in the 

 male, replaced by blue in the female, as in Psittacula diop- 

 thalma. In many South American Papilios, green spots on 

 the male are represented by red on the female ; and in several 

 species of the genus Epicalia, orange bands in the male are 

 replaced by blue in the female, a similar change of colour to 

 that in the small parrot above referred to. For fuller details 

 of the varieties of sexual coloration we refer our readers to 

 2 A. 



