African Nature Notes and Reminiscences

by Frederick Courteney Selous

The coloration of certain animals in the Arctic and sub-Arctic Regions is somewhat remarkable, as at certain seasons it is conspicuously out of harmony with its surroundings, and cannot therefore be protective. The musk ox retains its dark brown coat the whole year round, although it lives almost constantly amidst a snowy environment. Mr. Wallace tells us that the reason why the musk ox does not turn white is because it has no enemies to fear, and therefore has no need of a protective coloration. He says: "Then we have that thoroughly Arctic animal the musk sheep, which is brown and conspicuous; but this animal is gregarious, and its safety depends on its association in small herds. It is therefore of more importance for it to be able to recognise its kind at a distance than to be concealed from its enemies, against which it can well protect itself so long as it keeps together in a compact body." As, however, according to the experience of Arctic travellers, large numbers of young musk oxen are annually killed by wolves, this explanation of a case in which an animal is manifestly not protectively coloured does not seem altogether satisfactory. Mr. Wallace, it may be noted, calls special attention to the coloration of the giraffe, which he considers to be protective; yet nothing, I think, is more certain than that a far smaller percentage of giraffes are killed annually by lions in Africa than of musk oxen by wolves in Arctic America. If this is so, the musk ox has more need of protective coloration than the giraffe. The musk ox is, I think, the only one amongst the few truly Arctic mammals which does not turn white during the winter months, for, unlike the barren ground caribou, it does not migrate southwards in the autumn to the dark spruce forests, which change of habitat no doubt has had an influence on the colour of the latter animals; since Peary's caribou, the most northerly form of the genus, whose habitat lies far within the Arctic Circle, where trees of any kind are non-existent, is almost absolutely white in colour. In spite, however, of the fact that the caribou inhabiting Ellesmere Land and the adjacent land masses are white, and therefore harmonise well in colour with the snowy wastes amongst which they live, they form the principal food of the white wolves inhabiting the same regions, which hunt them by scent and run them down just as easily as the grey and black wolves of Alaska capture the dark-coloured and very conspicuous caribou which frequent the mountain ranges of that country. It appears to me that the colour of a caribou's coat, whether it be white, black, or brown, cannot afford it any protection against wolves, which probably possess as keen a sense of scent as any animals in the world, and must surely hunt entirely by scent during the long dark months of the Arctic winter. If this is so, then the great diversity in the coloration of the various species of caribou inhabiting the North American Continent must be due to some other cause than the necessity for protection against wolves, practically their only four-footed enemies.

Speaking of other Arctic animals, Mr. Wallace believes that the Arctic fox of necessity turns white in winter in order to enable it to capture the white Arctic hares upon which it chiefly lives. Very little, however, is known as to the life-history of these two animals. But if the Arctic foxes hunt by scent, as they almost certainly do, during the constant darkness of the long Arctic winter, and the hares burrow beneath the snow, and are caught as a rule when completely hidden from sight below its surface, I think it is arguable that the influence of environment has been at least as potent a factor in bringing about the white coloration of these animals in winter as the necessity for protective coloration. At any rate, in Alaska and the Yukon Territory of Canada, where the country is covered with snow for more than half the year, and where the hares are white throughout the long winter, the foxes are red, black, or a mixture of these two colours, all the year round, and the lynxes grey; yet these two species of carnivorous animals depend almost entirely on the hares for their food supply. It is somewhat remarkable that in the sub-Arctic forests of Alaska and the Yukon Territory, where the cold is intense and the ground covered with snow for so many months of every year, only the hares and the stoats amongst mammals turn white in winter. But in these countries the land is covered for the most part with dark spruce forests, the influence of which—if there is anything in the influence of environment—may have been greater in determining the coloration of the mammals of this district than that of the snow-covered ground.

During winter in the Yukon Territory, moose turn very dark in colour on the under parts of the body, and at this season of the year leave the thick forests and live in the comparatively open valleys amongst willow and birch scrub, where they are said to stand out like haystacks amidst their snowy surroundings. The local race of caribou (Rangifer osborni), which live all the year round on the treeless mountain plateaus, are very dark in colour (with the exception of their necks), and, as I myself can testify, stand out very plainly when the open ground they frequent is covered with snow. Of the various races of wild sheep inhabiting the mountains of Alaska, the Yukon Territory, and Northern British Columbia, some are white all the year round, and therefore very conspicuous in summer when there is no snow on the ground, though difficult to detect in the winter; some are grey, with white heads, necks, and rumps; whilst others are nearly black, and therefore very conspicuous in winter. Of the predatory animals the large timber wolves are, as a rule, pale greyish brown with black hairs on their backs and shoulders, but a considerable number are quite black; the foxes are either red or black, or of the intermediate coloration known as "cross"; whilst the wolverines, martens, and minks are rich dark brown, and the lynxes neutral grey. The stoat or ermine is the only carnivorous animal which turns white in winter in these countries.

It would thus appear that in the sub-Arctic Regions of North America the coloration of mammals does not obviously serve the purpose of concealing the herbivorous species from their enemies, or of enabling carnivorous animals to approach their prey unperceived. To come nearer home, we find that whereas in the Alpine regions of Europe the mountain hare turns white in winter, the chamois living in the same snow-covered ground becomes deep black. It is true that in winter chamois often leave the open mountains and live amongst the higher forests, where it may be said that their dark colour harmonises well with the dark foliage of the spruce trees; but I have hunted chamois in December in the mountains of Transylvania, when they were in full winter coat, and I certainly found that their dark coloration often made them conspicuous.

Turning to Africa, we have many instances of what seen in the open and at short range cannot possibly be called anything but conspicuous coloration, such as the jet black and pure white striping of the East African form of Burchell's zebra; the deep glossy black body and neck, with snow-white belly and parti-coloured face, of the sable antelope; the black and white face of the gemsbuck; the pure white face and rump of the bontebok, combined with the beautiful dark brown neck and sides and lilac tinted back; or the juxtaposition of the black and white in Thomson's gazelle—only to mention a few of the most noteworthy examples.

To me it seems that the influence of environment might very well be deemed sufficient of itself to cause all animals that have lived for long ages in treeless deserts under constant strong sunlight to assume the dull brown coloration which they undoubtedly possess; whilst Arctic conditions might be expected to cause the whitening of an animal's hair in the winter, or the play of the sun's light through the leaves and branches of trees and bushes to be responsible for a spotted or striped coat. In the case of a combination of black and white—the two most conspicuous colours in nature—such as may be seen in the adult cock ostrich or male sable antelope, why should it not be supposed that the law of sexual selection has come into play, as it probably has done in the production of the lion's mane and the exaggerated size of the horns in the male koodoo.

Having spent many years of my life in the constant pursuit of African game, I have certainly been afforded opportunities such as have been enjoyed by but few civilised men of becoming intimately acquainted with the habits and life-history of many species of animals living in that continent, and all that I have learnt during my long experience as a hunter compels me to doubt the correctness of the now very generally accepted theories that all the wonderfully diversified colours of mammals—the stripes of the zebra, the blotched coat of the giraffe, the spots of the bushbuck, the white face and rump of the bontebok, to mention only a few—have been evolved either as a means of protection from enemies or for the purpose of mutual recognition by animals of the same species in times of sudden alarm. Sexual selection and the influence of environment must, I think, have been equally potent factors in the evolution of colours in mammals, birds, reptiles, and insects.

In all recent articles which I have read by well-known naturalists on these subjects, it appears to be assumed that both carnivorous and herbivorous animals trust entirely to their sense of sight, the former to find their prey, and the latter to detect and avoid the approach of their enemies. Yet nothing is more certain than that all carnivorous animals hunt almost entirely by scent, until they have closely approached their quarry, and usually by night, when all the animals on which they prey must look very much alike as far as colour is concerned.

The wild dogs of Africa and the wolves of northern latitudes are not so completely nocturnal, it is true, as the large Felidae, but the former I know, and the latter I have every reason to believe, hunt, as a rule, by night and only occasionally in the daytime. In both these animals the sense of smell is enormously developed, and must be of far greater use to them in procuring food than the sense of sight, however acute that may be. In all my wanderings I have only seen African wild dogs chasing game in the daytime on four occasions. I once saw a single wild dog chasing a sable antelope in the daytime. This wild dog—which was, however, then too far away to enable me to see what it was—first ran past the sable antelope and behind it from where I was watching. It must then have been running on the trail, with its nose on the ground, and must have passed quite close to the animal it was pursuing without seeing it. Its nose, however, kept it on the antelope's tracks and soon brought it to close quarters, and then of course it continued the chase by sight. Now if this is the usual proceeding of African wild dogs, and I am convinced that it is, the value of assimilative coloration to animals on which the wild dog preys cannot be very great.

But not only do all carnivorous animals hunt by scent, and rely far more upon their olfactory organs than upon their keenness of sight to procure food, but, as all practical hunters very well know, the sense of smell is also very highly developed in all, or at any rate in most, of the animals on which the carnivora prey, and personally I am persuaded that all browsing and grazing animals in Africa trust as much to their noses as to their eyes both to avoid danger and to find members of their own species. The eyes of antelopes are quick to detect a moving object, but they are by no means quick to notice any unusual colour in a stationary object. I will relate an anecdote illustrating this point.