Not a single coot is to be seen upon the jhil. The explanation of this is that this particular tank dries up in the hot weather, and coots usually keep to those lakes that contain water all the year round.
Half a dozen terns form a conspicuous and beautiful feature of the jhil. As they sail overhead, with every now and then a descent to the water to secure a frog or small fish, their silvery wings stand out boldly from a dark cloud on the southern horizon. The terns at the jhil are all of the black-bellied species (Sterna melanogaster). The other species haunt rivers in preference to shallow lakes.
Last, but not least, mention must be made of Pallas’s fishing eagle (Haliaetus leucoryphus). One or more pairs of this bird are to be seen in the vicinity of every jhil. In the earlier part of the day they are active, screaming creatures, but when once they have made a good meal off a teal or some fish they become very sluggish. Two of them are sitting about fifty yards apart on a band alongside the jhil, looking like kites with whitish heads. They sit as motionless as statues. They are obviously feeling very lazy. Presently a king-crow (Dicrurus ater) comes up and, uttering that soft note which seems to be peculiar to the rainy season, makes repeated feints at the head of one of the fishing eagles. Save for a slight inclination of the head, the eagle pays no attention to the attack of its puny adversary. Eventually, the king-crow gives up in despair and flies off, probably to find something which will take more notice of his threatening demonstrations.
Even when I approach the fishing eagle the phlegmatic bird only flies a few yards. There is no creature more sluggish than a bird or beast of prey that has recently made a good meal.
VIII
BIRDS IN WHITE
Almost every species of bird and beast throws off an occasional albinistic variation or sport, which tends to breed true. Such sports are of two kinds—complete and incomplete albinos. In the former, the organism is totally devoid of external pigment, so that the eye looks red, there being no colouring matter in the iris to mask the small blood vessels in it. In the incomplete albinistic form the iris retains the pigment, so that the eye colour is normal. True albinos have very poor sight, hence when such sports occur in a species in a state of nature they soon perish in the struggle for existence. The white varieties with pigmented eyes are not handicapped by bad eyesight, but their whiteness makes them conspicuous to the creatures that prey upon them; so that, unless they are well able to defend themselves or unless they dwell in a region of everlasting snow, they tend to be eliminated by natural selection.
If protective colouring were as important to the welfare of birds as Wallaceians and modern Darwinians assert, all the birds of the Polar regions would be white and not a single white species would be found in the temperate zones or in the Tropics. That coloured species occur in the Arctic regions and white species in the Tropics is conclusive proof that in those particular cases, at any rate, it is not of paramount importance to the species that they be protectively coloured.
Finn and I have shown in The Making of Species that the ice-bound Arctic and Antarctic regions are not inhabited, as popular works on zoology would have us believe, by a snow-white fauna. We have shown that in the Polar countries the coloured species of birds outnumber the white species. I will, therefore, not dilate further upon this subject. It will suffice to repeat that in the area of eternal snow the white forms are at an advantage in the struggle for existence, as their whiteness tends to render them difficult to see, while, in regions where snow is unknown, such organisms labour under a disadvantage because of their conspicuousness, and, other things being equal, they ought not to be able to hold their own against less showy rivals.
The fact that white birds exist in the plains of India must mean that their colour is not a matter of great importance, that a conspicuous organism can survive in the fight for life provided it be otherwise well equipped for the contest. From this it follows that it is incorrect to speak of the whiteness of such organisms as the direct product of natural selection.
Let us take a brief survey of those birds of India of which the plumage is largely white, and try to discover how it is that each of them is able to hold its own in the struggle for existence, notwithstanding its showy plumage. These birds are the spoonbill, the egrets, the black-winged stilt, the avocet, the white ibis, the flamingo, adult cock paradise flycatcher, and certain of the gulls, terns, pelicans and storks, including the open-bill. With many of these every one is familiar. Accordingly, it will not be necessary to describe the sea gulls, the pelicans or the flamingo.