But, now, how is it that it is only the cock bird--the male--of all these Birds of Paradise who is so beautiful, whilst the poor hen--the female bird--is quite plain, in comparison? Well, I must tell you, first, that this is not only the case with Birds of Paradise, but that it is just the same with other birds as well. In most, if not all, of the beautiful birds I am going to tell you about, it is the male bird that is so _very_ beautiful, so that perhaps you will begin to think that this is the case with _all_ beautiful birds, and that there is no hen bird that has _very_ splendid or brilliant plumage. But this is not so at all. You would make a great mistake if you were to think that. In most of the parrots--those brightly-coloured birds that you know so well--the male and female are alike, and if you were to see a kingfisher--the star-bird that I told you about in the first chapter--gleaming and glancing up a river, you would not know whether it was the one or the other. The feathers of the female scarlet flamingo are almost--if not quite--as scarlet as those of the male; the cock robin's breast is not more red than the breast of the hen robin, at least you would find it difficult to tell the difference; male and female pigeons--and some of them are very splendid--are as bright as each other, and so it is with a very great number of other birds. Now does not this seem funny, that some male birds should be so much handsomer than their wives, whilst some _hen_ birds should be just as handsome as their husbands? Is there any way of explaining this, or, rather, do we know how to explain it? for there _is_ a way of explaining everything--a right way, I mean, of course. The difficult thing is to find it out. Well, there are some clever people who have been thinking about this funny thing, and they try to explain it in this way.