“Subsequently I made another experiment with linnets. In this case all three were allowed to fly in a big aviary-cage together, a method which I do not recommend.
“In this case, however, the handsomest cock, which showed much richer red on the breast, had a crippled foot, and proved, as I had expected, to be in fear of the other; nevertheless, the hen mated with him. It must be said, in justice to the duller bird, that he did not press the advantage his soundness gave him, but with a less gentle bird than the linnet this would have happened.”
It is obvious that there is a wide field for observation on these lines. In the case of large birds the experiment could be made still more conclusive by confining the three birds to be experimented on in a single enclosure, divided into three compartments by fences. The males should be placed each in a separate compartment, and have a wing clipped so as to prevent them leaving their respective compartments, while the hen should be allowed the power of flight so that she can visit at will any compartment.
Finn has also recorded (loc. cit.) some other observations bearing on the question of sexual selection. He writes:—
“One cannot observe or read about the habits of birds very much without finding out that, whatever may be the value of beauty, strength counts for a great deal. Male birds constantly fight for their mates, and the beaten individual, if not killed, is at any rate kept at a distance by his successful rival, so that, if he be really more beautiful, his beauty is not necessarily of much service to him. I was particularly impressed by this about a couple of years ago, when I frequently watched the semi-domesticated mallards in Regent’s Park in the pairing season. These birds varied a good deal in colour; in some the rich claret breast was wanting, and others had even a slate-coloured head instead of the normal brilliant green. Yet I found these ‘off-coloured’ birds could succeed in getting and keeping mates when correctly-dressed drakes pined in lonely bachelorhood; one grey-breasted bird had even been able to indulge in bigamy. That strength ruled here was obvious from the way in which the wedded birds drove away their unmated rivals, a proceeding in which their wives most thoroughly sympathised.
“Evidently, beauty does not count for much with the park duck, and the same seems to be the case with the fowl. As a boy, I often used to visit a yard wherein was a very varied assortment of fowls. Among these was one very handsome cock, of the typical black and red colouring of the wild bird, and very fully ‘furnished’ in the matter of hackle and sickle feathers. Yet the hens held him in no great account, while the master of the yard, a big black bird, with much Spanish blood, provided with a huge pair of spurs, was so admired that he was always attended by some little bantam hens, although they might have had diminutive husbands of their own class.
“It must be remembered, however, that these ducks and fowls had an unnaturally wide choice. In nature, varieties are rare, and the competing suitors are likely to be all very much alike; this makes matters very difficult for the observer, who may easily pass over small differences which are plain enough to the eyes of the hen birds.”
COURTSHIP OF SKYLARK
Illustrating display by a species with no decorative colouring or sex difference.