COLOURS OF ANIMALS 



that "it is so bold that the sight of man creates no alarm." 

 The beautifully-coloured Thaumastura cora "rarely permits 

 any other humming-bird to remain in its neighbourhood, but 

 wages a continual and terrible war upon them." The magni- 

 ficent bar-tail, Cometes sparganurus, one of the most imposing 

 of all the humming-birds, is extremely fierce and pugnacious, 

 " the males chasing each other through the air with surprising 

 perseverance and acrimony." These are all the species I find 

 noticed as being especially pugnacious, and every one of them 

 is exceptionally coloured or ornamented, while not one of 

 the small, plain, and less ornamental species are so described, 

 although many of them are common and well observed species. 

 It is also to be noticed that the remarkable pugnacity of these 

 birds is not confined to one season or even to birds of the 

 same species, as is usual in sexual combats, but extends to any 

 other species that may be encountered, while they are said 

 even to attack birds of prey that approach too closely to 

 their nests. It must be admitted that these facts agree well 

 with the theory that colour and ornament are due to surplus 

 vital energy and a long course of unchecked development. 

 We have also direct evidence that the males are more active 

 and energetic than the females. Mr. Gosse says that the 

 whirring made by the male Polytmus humming-bird is shriller 

 than that produced by the female ; and he also informs us 

 that the male flies higher and frequents mountains, while the 

 female keeps to the lowlands. 1 



Theory of Normal Colours 



The remaining kinds of animal colours, those which can 

 neither be classed as protective, warning, nor sexual, are for 

 the most part readily explained on the general principles of 

 the development of colour which we have now laid down. It 

 is a most suggestive fact that in cases where colour is required 

 only as a warning, as among the uneatable caterpillars, we 

 find, not one or two glaring tints only, but every kind of 

 colour disposed in elegant patterns, and exhibiting almost as 

 much variety and beauty as among insects and birds. Yet 



1 Some other cases are noticed at p. 317. For some further develop- 

 ments and illustrations of the theory of sexual colour, see Darwinism, 

 chap. x. 



