Beaver

The American beaver (Castor canadensis) is the largest rodent in North America and one of the most ecologically transformative animals on the continent. Adults weigh 35-65 pounds — exceptional individuals reach 90+ pounds — with broad scaly tails, prominent orange incisors, dense waterproof fur, and webbed hind feet.

Beavers are ecosystem engineers in the most literal sense. By felling trees and damming streams, a single beaver colony can transform a free-flowing creek into a wetland complex spanning many acres, supporting waterfowl, amphibians, fish, songbirds, and dozens of other species that depend on standing water habitat. Beaver dams trap sediment, recharge groundwater, slow stream flows, and create flood control that engineered infrastructure cannot match — all for free, maintained by the beavers themselves.

Pre-Columbian beaver populations are estimated at 60-400 million animals across North America, with beaver-engineered wetlands covering many millions of acres. The fur trade between 1600 and 1900 nearly exterminated the species — beaver pelts were the global standard for high-quality felt hats and drove much of European westward expansion across the continent. By 1900, beaver populations had fallen to perhaps 100,000 animals across the entire continent.

Beaver recovery through the 20th century has been substantial. Today's population is estimated at 10-15 million animals, restoring beaver-engineered wetlands across much of the continent. The species is now recognized as a critical conservation tool for restoring stream systems, mitigating drought, fighting wildfire severity (wetlands resist burning), and adapting to climate change.

Beavers cut down trees with their massive orange-stained incisors, which grow continuously throughout the animal's life — the orange color comes from iron compounds in the enamel that make beaver teeth harder than most steel. A single beaver can fell a 6-inch diameter tree in 20 minutes; large beaver dams can extend hundreds of feet and stand for decades, repaired generation after generation by the same beaver family.

The beaver is the national animal of Canada, the state animal of New York and Oregon, and is depicted on the Canadian nickel.