This book tells the stories of some of the baby mammals of the wilderness,—how they grow and learn day by day to take care of themselves. In hollow trees or down under water among the lily leaves, in the cool sea or on the rugged mountains, on the grassy plains or among the waving tree-tops, in the dark caves and burrows or hidden in the tangles underfoot,—all the world is alive with young creatures.

Bright eyes glitter and small paws patter, little noses sniff the air and sharp ears twitch. There is a rustling of leaves above and a crackling of twigs below, a splashing in the swamp and a silent bending of the grasses. In the sunshine or the rain, in the daytime or at night, life is busy everywhere on this beautiful old earth.

All the mammals are alike in having hair on some part of their bodies, in having teeth at some time in their lives, and in feeding the young with milk. But there are many, many kinds of mammals, of different shapes and sizes and colors. There are all sorts of babies, from the tiny mouse that could sleep in an eggshell to the big baby whale, twice as long as an ox. Some can swim like fishes; others can fly like birds. Some dig homes under the ground; others make their nests in hollow trees or caves. Some live in the mountains and some on the plains. Some live in the woods and some in the sea. Some eat grass, and others eat flesh; some eat nuts, some eat fruit, and some eat anything they can find.

Many of the mammals are alike in some ways. Squirrels and mice have strong teeth to gnaw with; the cow and elk eat grass and chew a cud, and the bear, wolf, and fox eat flesh.

Those mammals that are most alike are said to belong to the same order. For example, every animal with hoofs belongs to the Order of Hoofed Mammals. Every animal with four gnawing teeth in the front of its mouth belongs to the Order of Gnawing Mammals. Every animal that lives on flesh belongs to the Order of Flesh-Eating Mammals.

There are eleven of these groups, but the animals of North America belong to only eight of them. All the animals in the first group have pouches or pockets, of their own skin, in which to carry the young. The opossum belongs to this Order of Pouched Mammals. When he is a baby he is carried around in his mother’s furry pocket. Later he learns to hang by his feet and tail to a branch while he eats fruit. At night he trots through the woods and roots for insects with his pointed nose.

The manatee belongs to the Order of Sea-Cows. Sea-Cows are fishlike creatures that eat vegetable food in the sea or in rivers. The fat baby manatee lies in his mother’s arms as she balances herself on the end of her tail in the water. He learns to crawl about on the sandy bottom and munch water-plants.

The whale belongs to the Order of Whales. Though he lives in the deep ocean and looks like a monstrous fish, he is really a mammal. He has warm blood and a few bristles for hair. The baby whale is fed on milk at first. When he grows older he is taught to catch and eat water animals.

The wapiti, called the American elk, belongs to the Order of Hoofed Four-Foots. They eat grass and chew the cud. The story of an elk roaming over the mountains is almost the same as the story of any of the swift deer family.

The beaver and the squirrel and the rabbit belong to the Order of Gnawers. The beaver cuts down trees with his strong teeth, and builds dams and houses of sticks. The squirrel scampers along the branches, and sits up to nibble nuts in the shadow of his own bushy tail. The rabbit scuttles over the ground from one hiding-place to another, in his daily search for green grass and tender twigs to eat. Rats and mice are also Gnawers. Indeed, there are many more animals in this Order than in any of the others.

The bear and the wolf and the fox belong to the Order of Flesh Eaters. They are all mighty hunters. The swift wolf, the tricky fox, and the strong-armed bear all have many long, cutting teeth to tear their prey to pieces.

The mole belongs to the Order of Insect-Eaters. He lives underground, and learns to dig with his shovel-like hands. When his pointed teeth grow out he chases worms up and down and around, and gobbles them as fast as he can.

The bats belong to the Order of Wing-Handed Mammals. The baby bat is rocked to sleep in his mother’s wings. He learns to fly in the dark and to hunt the swift insects that hover above the roads and ponds. When winter is near he finds a gloomy cave. There he hangs, head downward, by the hooks on his claws, and sleeps till spring brings the warm weather again.

It is now countless years since the earth was new. It has changed from a bare, hot gloomy ball, covered with black rocks and muddy water, to a green, beautiful world. There are all kinds of living things in the ocean. In the forests insects hum above the flowers; birds fly from branch to branch; reptiles crawl beside the rivers. And everywhere—in the air and beneath the ground, on the land and under the water—live the mammals.

The opossum is the one with a pocket. The manatee is the only eater of grass in the sea. The whale is the biggest of all animals. The elk is the handsomest of the swift deer family. The beaver is the best builder. The squirrel has the prettiest tail. The rabbit is the most hunted by all its hungry enemies. The bear is the surliest one. The wolf is the fiercest. The fox is the shrewdest. The mole can dig better and faster than any of the others.