X COLOURS AND ORNAMENTS CHARACTERISTIC OF SEX 287 



charmed or excited by the fine display of plumage by the 

 males ; but there is no proof whatever that slight differences 

 in that disj^lay have any effect in determining their choice of 

 a partner. 



Display of Decorative Plumage. 



The extraordinary manner in which most birds display 

 their plumage at the time of courtship, apparently with the 

 full knowledge that it is beautiful, constitutes one of Mr. 

 DarAvin's strongest arguments. It is, no doubt, a very curious 

 and interesting phenomenon, and indicates a connection be- 

 tween the exertion of particular muscles and the develop- 

 ment of colour and ornament ; but, for the reasons just given, 

 it does not prove that the ornament has been developed by 

 female choice. During excitement, and when the organism 

 develops superabundant energy, many animals find it pleasur- 

 able to exercise their various muscles, often in fantastic ways, 

 as seen in the gambols of kittens, lambs, and other young 

 animals. But at the time of pairing, male birds are in a 

 state of the most perfect development, and possess an 

 enormous store of vitality ; and under the excitement of the 

 sexual passion they perform strange antics or rapid flights, as 

 much probably from an internal impulse to motion and exertion 

 as with any desire to please their mates. Such are the rapid 

 descent of the snipe, the soaring and singing of the lark, and 

 the dances of the cock-of-the-rock and of many other birds. 



It is very suggestive that similar strange movements are 

 performed by many birds which have no ornamental plumage 

 to display. Goatsuckers, geese, carrion vultures, and many 

 other birds of plain plumage have been observed to dance, 

 spread their wings or tails, and perform strange love-antics. 

 The courtship of the great albatross, a most unwieldy and 

 dull coloured bird, has been thus described by Professor 

 Moseley : " The male, standing by the female on the nest, 

 raises his wings, spreads his tail and elevates it, throws uj^ his 

 head with the bill in the air, or stretches it straight out, or 

 forwards, as far as he can, and then utters a curious cry."^ Mr. 

 Jenner Weir informs me that " the male blackbird is full of 

 action, spreads out his glossy Aving and tail, turns his rich golden 



^ Notes of a Naturalist on the Challenger. 



