African Nature Notes and Reminiscences. Frederick Courteney Selous
before proceeding further, I think I ought to say a word as to the points of resemblance and the differences between the bontebok and its near ally the blesbok.
In the latter, the wonderful contrasts of colour to be seen in the former are considerably toned down; but the difference between the two species is merely superficial. The general body colour of the blesbok is dark brown, but not so dark as on the neck and sides of the bontebok, and the delicate purply lilac colour of the back in the latter species is altogether wanting in the former. In the blesbok, too, the colour of the rump just above the tail, which in the bontebok is snow-white, is brown, though of a paler shade than any other part of the body. In the blesbok, too, the white face "blaze" is not continuous from the horns downwards as in the bontebok, but is interrupted above the eyes by a bar of brown. The legs, too, in the blesbok are not so white as in the bontebok, and whilst the horns of the latter species are always perfectly black, in the former they are of a greenish colour.
In a word, the differences between the bontebok and the blesbok are confined to the intensity of the colours on various portions of their hides, the former being much more brilliantly coloured than the latter.
Owing to the fact that the early Dutch settlers at the Cape first met with the antelopes which they called bonteboks on the plains near Cape Agulhas, and subsequently at first gave the same name to the nearly allied species which was discovered about one hundred years later in the neighbourhood of the Orange river, although these latter were undoubtedly blesboks and not bonteboks, a great confusion arose between these two nearly allied species, which I think that I was the first to clear up, in the article on the bontebok which I contributed to the Great and Small Game of Africa, published by Rowland Ward, Limited, in 1899. I cannot go into all the arguments I then used, but there can be no doubt that the animals which Captain (afterwards Sir Cornwallis) Harris first met with on the bontebok flats near the Orange river, in the Colesburg division of the Cape Colony, were blesboks and not bonteboks, and that all the millions of antelopes of the same species which he subsequently saw to the north of the Orange river and thought to be bonteboks were also all blesboks, and that he never saw a bontebok at all until after his return to the Cape, when he made a special journey to Cape Agulhas to secure specimens of that species, as he was "anxious to ascertain whether the animal rigorously protected in the neighbourhood of Cape Agulhas differed in any respect from that found in the interior, as pretended by the colonists."
I think myself that the correct determination of the true distribution of these two nearly allied species of antelopes is of the utmost importance to the question as to the influence of environment on the coloration of animals.
I imagine that the white-faced bontebok was evolved from the same ancestral form as the topi and the tiang of East and Northern Africa, for the new-born bontebok as well as the blesbok has a blackish brown face, and I believe—however fantastic this belief may appear to be—that the wonderfully rich and varied coloration of this remarkable antelope has been brought about purely through the influence of its exceptional environment. The plains where these animals live lie along the shore of a deep blue sea, the ground beneath their feet is at certain seasons of the year carpeted with wild flowers, which grow in such profusion that they give a distinct colour to the landscape, whilst above them rises a range of mountains of a considerable altitude, the upper parts of which are often covered with a mantle of pure white snow. I cannot imagine how any one who has seen bonteboks on the plains they inhabit can believe that their white rumps, faces, bellies, and legs, contrasting as they do so vividly with the dark rich brown of their sides and necks, can afford them any protection against their carnivorous foes; nor, although a white rump or face is a conspicuous mark, can I see the necessity of recognition marks for animals which live on open plains where the vegetation is short, and where an animal's whole body can be seen at a long distance.
In the blesbok, which also lives on open plains, the white rump patch so conspicuous in the bontebok has become pale brown, as, I think, through the influence of the dull monotonous colours of the dreary, dull-coloured country in which it lives. Ages ago no doubt the bontebok spread northwards through the karroo into the countries beyond the Orange and the Vaal rivers, but the gradual desiccation of the whole of South-Western Africa, which has been going on for a very long time, must have gradually driven all the bonteboks outside the Cape peninsula northwards to the Orange river, and completely separated them from their relatives still living near Cape Agulhas. These latter have retained all their richness of coloration brought about by the influence of their very striking surroundings, the deep blue of the sea, the snow on the mountains, and the bloom of innumerable wild flowers. The northern herds moved into open plains, in themselves very similar to the plains near Cape Agulhas, but they are never carpeted with wild flowers, nor are they skirted by a deep blue sea, nor ever overlooked by snow-covered mountains. Is it not possible that the differences which exist to-day between the coloration of the bontebok and the blesbok are entirely the result of the absence of any kind of colour but various monotonous shades of brown in the countries in which the latter species has now been living for a long period of time?
Not only has the rich and beautifully variegated body colouring of the bontebok become an almost uniform dark brown in the blesbok, but the snow-white disc on the rump of the former animal has turned to a pale brown in the latter, whilst the area of white on the face and legs of the bontebok has already been considerably contracted in the blesbok.
Personally, I look upon the blesbok as a faded bontebok; faded because it moved northwards out of the richly coloured environment in which it was first evolved into the dull-coloured plains of its present habitat, where it subsequently became isolated owing to the desiccation of the intervening country.
Could the opening up of Africa by the destructive civilised races have been delayed for a few hundred or a few thousand years, the blesbok would no doubt have lost the white blaze down the face as completely as it has lost the white disc over the tail, which is so conspicuous a feature in the coloration of its immediate ancestor, the bontebok. To those who believe that every spot or stripe or patch of colour on every animal is a beautiful illustration of the truth of the theory of protective coloration, this may seem a very fanciful idea. Yet I feel convinced that the influence of environment has played a greater part than is generally believed in the evolution of colour in living organisms. The weak point in the theory of protective coloration when applied to large mammals is the fact that all carnivorous animals are nocturnal and seek their prey habitually by night and by scent, and only occasionally by daylight and by sight.
I submit that the beautiful case in the Central Hall of the Natural History Museum at South Kensington—showing an Arctic fox, in its white winter coat, approaching a Polar hare, also in winter dress, and an ermine (stoat) hunting for ptarmigan (evidently by sight)—gives an entirely false view of the struggle for life as carried on by animals inhabiting the Arctic Regions, for it conveys the idea of the carnivorous animals of those snow-covered wastes hunting for their prey in a bright light and by eyesight alone.
But the truth is that the Arctic winter, during the long continuance of which all living resident creatures, with the exception of the musk ox, become white,[3] is one long night, in the gloom of which the wolves and the foxes and the ermines (stoats) search for and find their prey by scent alone, just as foxes, stoats, and weasels do in this country. As long as a hare gives out any scent at all, a fox will be able to follow and find it. The fact that the hare has turned white in the snow-covered ground in which it is living will not help it as long as it throws out the scent of its species, nor can it be shown that the foxes of the sub-Arctic regions, which never turn white in winter, have any greater difficulty in approaching and killing the white hares on which they live than the white Arctic foxes experience in catching the Polar hares.
[3] I do not admit that the raven is a truly Arctic bird. Nansen, in Farthest North, although he kept careful records of all the birds seen during the three years his expedition lasted, never mentions having seen a raven, which I believe has only penetrated into the Arctic Regions, as an excursionist, in comparatively recent times, following the whaling ships, and living on the carcases of the whales and seals killed.