by Kate Hofmann
Meet Bob. Bob's a builder. In fact, he comes from a whole family of builders. Bob is a beaver, and he makes his living building dams and lodges.
This builder has no tool belt. All the tools he needs are part of his beaver body. He doesn't chop trees—he chomps them with his strong, sharp teeth. His wide, flat tail braces him like a kickstand as he gnaws. His nimble front paws are made for picking up branches and mud.
Bob has even more gear for working in the water. There, his tail acts as a rudder when he swims. His webbed back feet kick powerfully. Thick, waterporof fur keeps him warm and dry. When he dives, his ears and nose close tight to keep water out. Extra clear "eyelids" serve as built-in swim goggles. He can even close his lips behind his teeth so that he can carry a mouthful of sticks without swallowing water.
A beaver's front teeth never stop growing, so gnawing on wood (top left) keeps them from getting too long.
Smack! At the first sign of a predator or other danger, Bob slaps the water with his flat tail (above). This warns other beavers to dive to safety.
To build a dam, beavers begin by gnawing down trees (above right). Then they pile logs and branches across a stream and add sticks and mud to plug the holes. A pond forms behind the dam (above).
Let's see what happens when Bob and his whole family of beaver builders put their built-in tools to work.
CAN WE BUILD IT?
When Bob's construction company gets busy, look out! A family of beavers can quickly turn part of a forest into a wetland. It all starts when they build a dam across a stream. Water collects behind the dam, forming a pond. The pond is the whole point—because a pond makes a perfect place to build a lodge, the beavers' home.
YES, WE CAN!
With the dam complete, the water is just right—not too deep and not too shallow. Bob and his family can now build a lodge that's surrounded by water. Like a castle with a moat, the lodge will be safe from enemies. Predators such as wolves, bears, and lynxes would find it hard to get inside. Below, you'll see how the beavers build their castle.
In the pond, Bob piles sticks and mud into a mound (above). Inside the mound, he digs and chews to make a cozy room.
A beaver mother usually has between two and four babies at a time (above right). When the kits are born, they already have fur and teeth. Within just a few days, they may try swimming for the first time.
Bob's lodge is a dry, warm place. But the doors are all underwater. To get inside, he and his family swim up through watery tunnels that lead to the inner room. The lodge's roof and walls are thick, keeping out the cold in winter and keeping out predators all year long.
Bob can't build all the time. He needs to eat, too! Beavers are herbivores (plant-eaters). When they cut down trees, they eat the leaves and twigs and nibble the tender bark from the small branches.
To get ready for winter, Bob makes a big pile of branches in the water near the lodge. Then, even if the surface of the pond freezes over, he and his family can swim out to their "pantry," grab a stick, and take it back to the lodge to munch on the bark.
ALL IN THE FAMILY
Beavers babies (called kits) are born in the spring. They stay with their parents for two winters. After the first winter, a new litter of kits is born, and the older siblings help take care of them. At the end of the next winter, the two-year-old beavers leave to build their own homes. That's when Bob's sons and daughters start up their own construction companies, carrying on the family business!