In the case of polygamous species there can be no doubt that there is considerable competition among males for their wives. It cannot be said that the contention is so well established in the case of monogamous species. D. Dewar suggests that circumstances may occur in which the hens have to fight for the cock, or in which the male is in the happy position of being able to select his mate. He states his belief that in many cases the selection is mutual, as in the case of human beings. “I have seen,” he writes, on page 13 of _Birds of the Plains_, “one hen Paradise Flycatcher (_Terpsiphone paradisi_) drive away another and then go and make up to a cock bird. Similarly, I have seen two hen orioles behave in a very unladylike manner to one another all because they both had designs on the same cock. He sat and looked on from a distance at the contest.” Darwin quotes, on page 500 of _The Descent of Man_, a case of a male exercising selection: “It appears to be rare when the male refuses any particular female, but Mr Wright of Geldersley House, a great breeder of dogs, informs me that he has known some instances: he cites the case of one of his own deerhounds who would not take any notice of a particular female mastiff, so that another deerhound had to be employed.” Similarly, Finn records, in _The Country-Side_ for August 29th, 1908, that the male Globose Curassow (_Crax globicera_) in the London Zoological Gardens, which bred with the female Heck’s Curassow (_C. hecki_), as related on p. 104, selected the hen of this very distinctly coloured form or species in preference to any of the typical hens of his own kind. Male Attractiveness The cases on record of cocks being in a position to select their mates are comparatively rare, while instances of selection on the part of the hens are far more numerous. Hence it would seem that the sex, which is in a minority, and so has the opportunity of selecting a mate, does exert a choice and prefer one particular individual; and that, for the reasons pointed out by Darwin, it is in most cases the female who is in the position of being able to pick and choose her mate. It is, as Darwin truly said, far more difficult to decide what qualities determine the choice of the female. He believed that it is “to a large extent the external attractions of the male, though no doubt his vigour, courage, and other mental qualities come into play.” Darwin argued that it is the love of hen birds for “external attractions” in cock birds that has brought into being all the wonderful plumes that characterise such birds as the peacock. “Many female progenitors of the peacock,” he writes, on page 661 of _The Descent of Man_ (ed. 1901), “during a long line of descent, have appreciated this superiority, for they have unconsciously, by the continued preference of the most beautiful males, rendered the peacock the most splendid of living birds.”