Found in wetlands across nearly every province, the beaver is the largest rodent in North America and, of all the country's wildlife emblems, has the widest appeal, appearing on the five-cent coin. Adult weights range from about sixteen to over thirty kilograms, making the beaver heavier than most other rodents. It is built for life in the water, with webbed hind feet, a broad flat tail, and long orange front teeth that never stop growing. Once hunted in vast numbers for its fur, this hardy animal was driven close to extinction before trapping was limited and the population slowly recovered.

The beaver is famous above all for building dams. Working mostly at night, a family fells trees with their teeth and drags the branches into a stream to slow the flowing water. Behind the dam a pond forms, and in the middle of it the beavers raise a dome-shaped lodge of sticks and mud, with an underwater entrance that keeps out wolves and other predators. These ponds do far more than shelter beavers. They store water during dry spells, trap sediment, and cater to fish, frogs, and birds alike, which is why the beaver is often called an ecosystem engineer.