On the Move: Caribou of the North
1Many animals stay in one area all year, but caribou are almost always on the move. Caribou are large deer that live in the far north, in places such as Alaska, Canada, and Greenland. In Europe and Asia, the same kind of animal is called a reindeer. This report shows how caribou are built for cold places and how they travel to find food.
2Caribou are built for the cold. Their thick coats have two layers. The hairs in the outer layer are hollow, which means they have empty space inside. The air in these hairs helps hold in a caribou's body heat, and it even helps the animal float when it swims across a river.
3A caribou's hooves are another great tool. Each hoof is wide and spreads out when the caribou steps down, a lot like a snowshoe. This keeps the animal from sinking deep into soft snow. When a caribou swims, its big hooves work like paddles that push it through the water.
4One thing that makes caribou unusual is their antlers. In most kinds of deer, only the males grow antlers. Caribou are different: both males and most females grow them. Every year, caribou shed their antlers and grow a new set.
5In winter, caribou eat mostly lichen. Lichen is a living thing made of a fungus and an alga growing together. It grows on rocks and on the ground, and it can survive cold, dry weather where few plants grow. Ms. Olsen told me, "A caribou can sniff out lichen under the snow and dig right down to it with its hooves."
6To find enough food, many caribou herds migrate, which means they travel from one area to another as the seasons change. In spring, herds walk north to the tundra, a cold, flat land with no trees. There, the females give birth to their calves. A calf can stand and walk soon after it is born, so it can keep up with the herd. In fall, many herds head back south to forests, where trees give some shelter from winter storms. Ms. Olsen wrote, "When a big herd crosses a river, the water seems full of antlers from one bank to the other."
7From their hollow hairs to their snowshoe hooves, caribou have just what they need to live and travel in the far north.