(c) Neal Kelso, some rights reserved (CC BY)

American Beaver

(c) ddt_biology, some rights reserved (CC BY-NC)

Muskrat

VS

Both are large aquatic rodents found in Great Falls National Park and throughout Virginia, but beavers are much larger (40+ lbs) with flat tails and build dams, while muskrats are smaller (3 lbs) with rat-like tails and create push-ups.