African Nature Notes and Reminiscences 10
I cannot see that facts support the opinion that the uniform dull brown
coloration of both sexes of the southern race of situtunga has been
brought about for the purpose of protection from carnivorous enemies.
During the daytime these animals live in the midst of beds of reeds
growing in water where they cannot be approached except by wading; but
at night they are often killed by leopards, and perhaps sometimes by
lions, whilst feeding just outside the reed beds, on open ground which
has perhaps been recently swept by a veld fire, and where young reeds
and grass are just sprouting. At such a time their actual colour can
be of no more use in the way of protecting them from their keen-scented
feline foes than if it were black or red or grey. To me it seems far
more probable that the situtunga has gradually lost the stripes and
spots of the ancestral form from which it is derived, and assumed a
uniform dull brown coloration, because it has lived for ages amongst
reed beds of one dull monotonous colour, than because a uniform brown
coat affords it a special protection against carnivorous foes.
I gather from the writings of Mr. A. R. Wallace and other well-known
naturalists that, whereas the coloration of all animals is supposed to
be due to the need of protection from carnivorous beasts, many species
have developed in addition what are known as recognition marks, to
enable them to distinguish members of their own species from nearly
allied forms, or to help them to quickly recognise and rejoin the
members of the herd or family from which they may have been separated.
That many large mammals belonging to different genera, and living
in widely separated parts of the globe, are marked with conspicuous
patches of white on the rump, neck, or face, or throw up bushy tails
when running, showing a large white under surface, is an indisputable
fact, though it is not possible to say that the possession of such
a conspicuous coloration is absolutely necessary to the well-being
of any particular species, because there will nearly always be other
species living in the same country, and subject to the attacks of the
same predatory animals, in which these so-called recognition marks are
absent. However, on the supposition that carnivorous animals hunt by
sight, it seems to me that no animal can be said to be protectively
coloured which is marked in any way so conspicuously as to be
recognisable by others of its own species at a distance, for it would
be equally recognisable by all predatory animals, and caribou and
white-tailed deer or African antelopes cannot escape from wolves or
wild dogs by running like rabbits into burrows.
Personally, I cannot see why large antelopes which live in herds on
open plains should require special recognition marks, as in such
localities the bulk of an animal's whole body would be plainly
visible at a great distance no matter what its colour might be. If an
antelope became separated from its fellows by night, all so-called
recognition marks would be invisible at a very short distance. It must
be remembered, however, that every species of animal has a peculiar and
very distinctive smell of its own, and my own observations would lead
me to believe that most wild animals recognise one another, as a rule,
more by scent than by sight.
It seems difficult to believe that there can be any truth in the theory
suggested by Mr. Wallace, that recognition marks have been developed in
certain species of large mammals because they are necessary to enable
nearly allied species of animals to know their own kind at a glance,
and so prevent interbreeding; for the ranges of very nearly allied
forms of one genus, such as the various species of hartebeests and
oryxes, or the bontebok and the blesbok, very seldom overlap, and so
each species keeps true of necessity and without the help of special
recognition marks. Where the ranges of two nearly allied species do
overlap interbreeding probably will take place.
There seems little doubt that the species of hartebeest known as
Neumann's hartebeest has interbred with Jackson's hartebeest in
certain districts where the ranges of the two species meet. In the
neighbourhood of Lake Nakuru, in British East Africa, I shot, in
February 1903, a hartebeest which was not a Jackson's hartebeest, but
which closely resembled an animal of that species in the character of
its horns and the measurements of its skull, whilst all the others in
the same herd appeared to be true Neumann's. I have known too of one
undoubted case of the interbreeding of the South African hartebeest
(_B. Caama_) with the tsessebe (_Damaliseus lunatus_).
This animal (an adult male) was shot by my friend Cornelis van
Rooyen in Western Matabeleland, where the ranges of the two species
just overlap. In coloration it was like a tsessebe, but had the
comparatively bushy tail of the hartebeest, whilst its skull and horns
(which are, I am glad to say, in the collection of the Natural History
Museum at South Kensington) are exactly intermediate between those
of the two parent species. This skull has been very unsatisfactorily
labelled "supposed hybrid between _B. Caama_ and _D. lunatus_." But as,
when I presented it to the Natural History Museum, I gave at the same
time a full description of the animal to which it had belonged, which I
got from the man who actually shot it, there is no supposition in the
matter. If the skull and horns in question are not those of a hybrid
between the South African hartebeest and the tsessebe, then they must
belong to an animal still unknown to science.
There is, I think, no large mammal in the whole world whose coat shows
a greater richness of bloom and a more abrupt contrast of colours than
the bontebok, so called by the old Dutch colonists of the Cape because
of its many coloured hide, for _bont_ means spotted, or blotched, or
variegated. The whole neck, the chest, the sides and under parts of
the head, and the sides of the body of this remarkable antelope are of
a rich dark brown, and the central part of the back is of a beautiful
purple lilac; whilst, in strong contrast to these rich dark colours,
the whole front of the face, a good-sized patch on the rump, the whole
belly, and the legs are of a pure and brilliant white. In life, and
when they are in good condition, a wonderful sheen plays and shimmers
over the glossy coats of these beautifully coloured animals, which
fully atones for the want of grace and refinement in the shape of their
heads and the heavy build of their bodies.
Now, a practical acquaintance with the very limited extent of country
in which the bontebok has been evolved, and where the survivors of the
race still live, makes it quite impossible for me to believe that the
extraordinarily brilliant colouring of this species of antelope can
have been gradually developed in order to make it inconspicuous and
therefore difficult of detection by carnivorous animals, nor can I
believe that it has been evolved for the purpose of mutual recognition
between individuals of the species; for although the snow-white blaze
down the face or the white rump patch might very well subserve such a
purpose, I see no necessity, looking to the habitat and the habits of
the bontebok, for special recognition marks.
Now, 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.
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