American Beaver

Castor canadensis

American Beaver (Castor canadensis) — Nature’s Overachieving Wetland Architects

The American Beaver (Castor canadensis) is North America’s largest rodent and a playful ecosystem engineer that builds dams, lodges, and wetlands with nonstop energy and impressive skill.

Habitat
Ponds, lakes, rivers, streams, marshes with woody vegetation
Size
2–4 ft long plus 10–12 in tail; 35–65 lbs
Diet
Bark cambium, leaves, buds, aquatic plants
Range
Most of North America except arid Southwest and southern Florida
Conservation
Least Concern; rebounded after historical overhunting

Habitat & range

Picture a busy engineer with a flat tail and a mission: the American Beaver thrives across most of North America, from Alaska and Canada down through the lower 48 (skipping the driest deserts and southern Florida) into northern Mexico. These semi-aquatic rodents love slow-moving freshwater—ponds, lakes, rivers, streams, and marshes—where woody snacks grow right along the banks. They turn ordinary waterways into deep, protected ponds that become bustling wildlife neighborhoods.

Diet & foraging

Strict herbivores with a serious wood habit, American Beavers chew the tasty cambium layer under bark from willow, aspen, poplar, birch, maple, and alder. They also munch leaves, buds, roots, and aquatic plants, holding food in clever front paws like tiny lumberjacks on break. Their iron-rich orange incisors never stop growing and stay razor-sharp for felling trees. Come winter, they cache branches underwater in a natural fridge so dinner stays fresh under the ice.

Behavior & adaptations

American Beavers are master builders and devoted family types. They stack sticks, mud, and rocks into watertight dams, then craft cozy dome lodges with underwater entrances that keep everyone safe and dry. A loud tail slap on the water serves as the ultimate “predator incoming!” alarm. Mostly nocturnal or crepuscular, they swim up to 5–6 mph, hold their breath for 15 minutes, and use built-in goggles plus closable ears and nostrils. Monogamous pairs lead tight colonies of up to eight, even digging canals to float logs home like nature’s own log drivers.

Ecological role

These rodents are genuine keystone species whose dams create wetlands that boost biodiversity for fish, frogs, birds, and bugs while fighting erosion, filtering water, and easing floods. American Beaver appears as a Mammalia creature card in Wilder TCG. Their landscape-scale remodeling helps entire ecosystems stay healthy and resilient.

Fun facts about American Beaver

  • Iron in their enamel turns teeth bright orange and makes them self-sharpening chainsaws.
  • Some beaver ponds are so big they show up on satellite photos from space.
  • They can swim 5–6 mph and stay underwater 15 minutes—longer than most humans hold their breath.
  • Beavers dig food-transport canals and stash branches underwater like a winter pantry.
  • That flat tail works as rudder, balance beam for carrying logs, and built-in drum for danger alerts.

American Beaver vs Platypus

The larger, powerfully built beaver drives off the smaller platypus with its sharp incisors and strong swimming ability.

In a quiet freshwater stream where their ranges might overlap, the beaver spots the platypus foraging along the muddy bottom. The platypus relies on its sensitive bill to hunt small invertebrates and its venomous ankle spurs for defense, but it is far lighter and less equipped for direct confrontation. The beaver, with its broad flat tail and chisel-like teeth suited for felling trees, slaps the water in warning before advancing. Its larger size and ability to stay submerged longer give it the edge in this shared aquatic habitat. The platypus retreats to avoid injury, leaving the beaver to continue its dam-building undisturbed.

Read more about Platypus.

Common questions about American Beaver

What animals look like beavers?

The usual lookalikes are the nutria (round, rat-like tail and white whiskers), the muskrat (much smaller, with a thin tail flattened side to side), the capybara (almost no tail), the groundhog (a dry-land burrower with white teeth), the mountain beaver (not a real beaver), and the river otter (a long, furry, tapering tail). Only a beaver has a broad, flat, scaly paddle for a tail. See our guide to animals that look like beavers.

Is a beaver a rodent?

Yes. The American beaver belongs to the order Rodentia and the beaver family, Castoridae. It is the largest rodent in North America and the second-largest in the world, after South America's capybara. Its bright orange incisors keep growing throughout its life, as rodent teeth do.

Do beavers eat fish?

No, beavers are strict herbivores. They eat bark and the soft cambium layer beneath it (willow, aspen, poplar, maple, birch, and alder are favorites), plus leaves, buds, roots, and water plants. Microbes in their gut help them digest woody cellulose, which most mammals can't break down.

Why do beavers build dams?

Dams slow the stream and back up a pond deep enough to keep the lodge's entrances underwater, where predators can't easily reach them. The deep water also serves as a winter pantry: beavers store branches underwater and swim out under the ice to feed. The wetlands this creates help fish, frogs, and birds, and slow floodwater.

What is the difference between the American beaver and the Eurasian beaver?

They are two separate species that look almost identical: Castor canadensis in North America and Castor fiber across Europe and northern Asia. Both have flat, scaly tails and orange, iron-reinforced teeth. In the field, location is the practical way to tell them apart. Eurasian beavers more often live in bank burrows and build dams only where they need to.

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