To be out of the fashion
is there quite literally to be out of the world: no half-measures will
suit the stern decree of polar biology; strict compliance with the law
of winter change is absolutely necessary to success in the struggle for
existence.
Now, how has this curious uniformity of dress in arctic animals been
brought about? Why, simply by that unyielding principle of Nature which
condemns the less adapted for ever to extinction, and exalts the better
adapted to the high places of her hierarchy in their stead. The
ptarmigan and the snow-buntings that look most like the snow have for
ages been least likely to attract the unfavourable attention of arctic
fox or prowling ermine; the fox or ermine that came most silently and
most unperceived across the shifting drifts has been most likely to
steal unawares upon the heedless flocks of ptarmigan and snow-bunting.
In the one case protective colouring preserves the animal from himself
being devoured; in the other case it enables him the more easily to
devour others. And since 'Eat or be eaten' is the shrill sentence of
Nature upon all animal life, the final result is the unbroken whiteness
of the arctic fauna in all its developments of fur or feather.
Where the colouring of nature is absolutely uniform, as among the arctic
snows or the chilly mountain tops, the colouring of the animals is
uniform too. Where it is slightly diversified from point to point, as in
the sands of the desert, the animals that imitate it are speckled or
diversified with various soft neutral tints.
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