The tiger is made so invisible by his wonderful colour that, when he crouches in the bright sunlight amid the tall brown grass, it is almost impossible to see him. But the zebra and the giraffe are the kings of all camouflagers! So deceptive are the large blotch-spots of the giraffe and his weird head and horns, like scrubby limbs, that his concealment is perfect. Even the cleverest natives often mistake a herd of giraffes for a clump of trees. The camouflage of zebras is equally deceptive. Drummond says that he once found himself in a forest, looking at what he thought to be a lone zebra, when to his astonishment he suddenly realised that he was facing an entire herd which were invisible until they became frightened and moved. Evidently the zebra is well aware that the black-and-white stripes of his coat take away the sense of solid body, and that the two colours blend into a light gray, and thus at close range the effect is that of rays of sunlight passing through bushes. The arctic animals, with few exceptions, are remarkable for imitating their surroundings; their colour of white blends perfectly with the snow around them. The polar bear is the only white bear, and his home is always among the snow and ice. The arctic fox, alpine hare, and ermine change to white in winter only, because during the other seasons white would be too conspicuous. The American arctic hare is always white because he always lives among the white expanses of the Far North. Both foxes and stoats are carnivorous and feed upon ptarmigan and hares, and they must be protectively coloured that they may catch their prey. On the other hand, Nature aids the prey by providing them with colours that enable them to escape the attention of their enemies. The young of many of the arctic animals are covered with fluffy white hair, so that while they are too young to swim they may lie with safety upon the ground and escape the attention of polar bears; but in the antarctic regions, where there are few enemies to fear, the young seals, for instance, are exactly the colour of their parents. The most remarkable exception of mimetic colouring among the animals of the polar regions is the sable. Throughout the long Siberian winter he retains his coat of rich brown fur. His habits, however, are such that he does not need the protection of colour, for he is so active that he can easily catch wild birds, and he can also subsist upon wild berries. The woodchuck of North America retains his coat of dark-brown fur throughout the long, cold winters. The matter of his obtaining food, however, is easy, for he lives in burrows, near streams where he can catch fish and small animals that live in or near the water.