"I'm not a beaver!" When they are in the water, it's easy to see why people mistake muskrats for beavers. Both are semi-aquatic rodents that are brown and furry. Once out of the water, you can spot the differences between the two species. Muskrat: Skinny tail. Smaller in size (adults weigh around 4 pounds). Pointy face. Good at scritches. Beaver: Big flat tail. Much larger (adults weigh between 30 - 60 pounds). Probably also good at scritches. Video by K. Theule/ USFWS Video description: A small