[Illustration: THE YELLOW SUNBIRD. (ARACHNECHTHRA ZEYLONICA)]
The hens of all three species are homely-looking birds, difficult to distinguish one from the other. The upper plumage of each is dingy brown and the lower parts dull yellow. Many ornithologists declare that sexual dimorphism, such as is here displayed, is due to the greater need of the hen for protection when sitting on the eggs. These people allege that if the hens of brightly plumaged species were as showy as the cocks, they would be conspicuous objects when brooding, and so fall easy victims to birds of prey. This is a theory typical of the arm-chair naturalist, or of him who studies nature through the grimy panes of a museum window. Like all such theories, it is tempting at first sight, but is untenable because it fails to take cognisance of facts with which every field-naturalist should be acquainted. In the first place, birds of prey rarely attack stationary objects: they look out for moving quarry. Secondly, the cock of many species, such as the paradise flycatcher (_Terpsiphone paradisi_), although he is far more showy than the hen, sits on the eggs in the open nest quite as much as she does. In this case what is sauce for the goose is sauce for the gander; if she needs protective colouring, so does he. It is true that the cock sunbird never takes a turn on the nest; he is not a family man, but a gay young spark, who goes about bravely attired, with his hand upon the handle of his sword, ready to draw it upon the least provocation. A more pugnacious little bird does not exist. While the hen is laboriously building the wonderful little nest, he spends his time in drinking and revelry, with an occasional visit to the growing nursery to criticise its construction. Hence it might seem that, in the case of the sunbird, the above-mentioned explanation of the sexual dimorphism is the true one. Unfortunately, the nest is not an open one, but a little mango-shaped structure with an entrance at the side, so that the hen when sitting in it is not visible from above. In this case, therefore, as in so many others, we must seek a new explanation of this difference in the appearance of the cocks and hens.
The nest is in shape and size like a mango. It hangs down from the end of a branch, or any other convenient object. It is composed of dried grass, leaves, cocoons, bits of paper, and any kind of rubbish, held together by means of cobweb and some glutinous substance. There is an entrance at the side, over which is a little porch that serves to keep out rain and sun, but this porch is seen in every nest, even when the bird builds, as it very frequently does, in a verandah. A sunbird recently made its nest in the verandah of a friend of mine; the latter came to me and expressed his contempt for the intellect of the little architect, since she had been fool enough to construct a porch, although the nest was built under cover. He forgot that the building of nests is largely an instinctive act, that each bird builds on a fixed plan, learned by it in “the school of the woods.”