THE BREEDING SEASON 27 



The brilliant colours of the male lump-sucker {Gydopterus Imnpus), 

 and of other fish 1 at the time of breeding, are probably due to the 

 same causes as in the dragonet.^ 



The tail of the lyre-bird, tvhich is shed at the end of the breeding 

 season, not to be renewed again in the same form until the following 

 summer, the brilliant plumage of the breeding drake, the more intense 

 colouring of the phalarope, and many other birds during the season of 

 courtship, are familiar instances of the same kind of phenomena.^ The 

 J^emarkable plate of horn which is developed in the upper mandible 

 of. the pelican in the breeding season, and bodily shed at the end of 

 it, and the "gular pouch" in the throat of the breeding bustard, are 

 examples of a more special kind, the existence of which, however, 

 must be connected, either directly or indirectly, with the eontem- 

 popneous increase of sexual activity and the enhanced vitality which 

 accompanies it. 



With birds, however, the assumption of the most perfect male 

 plumage is not necessarily synchronous with the period of enhanced 

 vitality. Thus Grinnell * says that in the linnet " the brilUant hue 

 of the nuptial dress " is acquired in August, or several weeks after 

 the season of mating, instead of immediately preceding it, and so is 



1 Numerous instances are given by Darwin, loo. cit., both for fishes and 

 Amphibians. 



^ The nuptial changes which occur in fishes are not necessarily in the 

 direction of increased brilliance of coloration. Miss Newbigin describes 

 these changes in the salmon as follows : " When the fish comes from the 

 sea the skin is of a bright silvery hue, while the flesh has the familiar strong 

 pink colour. The small ovaries are of a yellow-brown colour. As the 

 reproductive organs develop during the passage up the river, certain definite 

 colour-changes occur. The skin loses its bright silvery colour, and, more 

 especially in the male, becomes a ruddy-brown hue. At the same time the 

 flesh becomes paler and paler, and in the female the rapidly growing ovaries 

 acquire a fine orange-red colour. The testes in the male remain a creamy 

 white. After spawning the skin tends, in both sexes, to lose its ruddy 

 colour and to regain the bright silvery tint ; the flesh, however, remains pale 

 until the kelt has revisited the sea" {Report of Scottish Fishery Board, 1898). 



Barrett-Hamilton {Proc. Camb. Phil. Soc, vol. x., 1900, and Annals and Mag. 

 of Nat. Hist., vol. ix., 1902) draws attention to many such sexual phenomena, 

 and more especially to those oocurrmg in the spawning season in certain 

 salmonoid fishes of the genus Onchorhynchus. The fish undergo extraordinary 

 changes in colour and shape, and, since they die when spawning is accomplished, 

 it is argued that the changes cannot have any sesthetic significance, but 

 represent a pathological condition in which the fish become continually more 

 feeble and eventually succumb. 



3 Beebe (" Preliminary Eeport on an Investigation of the Seasonal Changes 

 of Colour in Birds," Amer. Nat., vol. xlii., 1908) describes an experi- 

 ment in which certain tanagers and bobolinks, which had been prevented 

 from breeding, were kept throughout the winter in a darkened chamber 

 with a somewhat increased food-supply. As a consequence the nuptial 

 plumage was retained until the spring, when the birds were returned to 

 normal conditions. . They shortly afterwards moulted. The breeding plumage 

 was then renewed, so that in this case the dull winter plumage was never 

 acquired. 



* Grinnell, "Concerning Sexual Coloration," /SfcieJice, vol. xxxiii., (Jan.) 1911. 



