Beaver

The beaver is a large rodent that lives in rivers, lakes, and streams across North America, Europe, and parts of Asia. It is the second-largest rodent in the world, after the South American capybara. An adult beaver weighs between 35 and 70 pounds, about as much as a medium-sized dog. Beavers have thick brown fur, webbed back feet, and a flat, scaly tail shaped like a paddle.

Beavers are famous for building things. Using their strong front teeth, they chew down small trees and drag the branches into the water. They stack the branches, mud, and stones to build two kinds of structures: dams and lodges. A dam blocks a stream and creates a pond. A lodge is a dome-shaped home in the middle of that pond, with underwater entrances that predators cannot reach.

The biggest beaver dam ever found is in Alberta, Canada. It stretches more than 2,800 feet, longer than eight football fields laid end to end. Scientists spotted it from space using satellite photos. Beavers built it slowly over many years, one branch at a time.

Those orange front teeth never stop growing. Beavers have to keep chewing wood to wear them down, or the teeth would get too long. A beaver can chop through a tree five inches thick in a single night.

Beavers change the world around them more than almost any other animal. When they build a dam, the pond behind it floods the land and creates a wetland. Fish, frogs, ducks, moose, and many other animals come to live there. Scientists call beavers "ecosystem engineers" because they reshape whole landscapes. In recent years, wildlife managers have even brought beavers back to dry areas on purpose, hoping their dams will store water during droughts and slow down wildfires.

Beavers were almost wiped out in the 1800s. Their thick, waterproof fur was used to make fashionable hats in Europe and America, and hunters trapped them by the millions. By 1900, only a small number were left. Laws to protect them, along with changing fashion, let the beavers slowly recover. Today there are millions of them again.

A beaver family usually has two parents and their young, called kits. They share the lodge, groom each other's fur, and work together on repairs. If you ever hear a loud slap on the water at dusk, that is a beaver's tail. It is a warning to the family that something is coming.