Nutria
Nutria. USFWS photo.
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Nutria have short legs and a robust, highly arched body that is approximately 24 inches long. Their round tail is from 13 to 16 inches long and scantily haired. Males are slightly larger than females;the average weight for each is about 12 pounds. Males and females may grow to 20 pounds and 18 pounds, respectively.
The dense grayish underfur is overlaid by long, glossy guard hairs that vary in color from dark brown to yellowish brown. The forepaws have four well-developed and clawed toes and one vestigial toe. Four of the five clawed toes on the hind foot are interconnected by webbing; the fifth outer toe is free. The hind legs are much larger than the forelegs. When moving on land, a nutria may drag its chest and appear to hunch its back. Like beavers, nutria have large incisors that are yellow-orange to orange-red on their outer surfaces.
In addition to having webbed hind feet, nutria have several other adaptations to a semiaquatic life. The eyes, ears, and nostrils of nutria are set high on their heads. Additionally, the nostrils and mouth have valves that seal out water while swimming, diving, or feeding underwater. The teats of the female are located high on the sides, which allows the young to suckle while in the water. When pursued, nutria can swim long distances under water and see well enough to evade capture.

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Muskrat
Muskrat. Photo by Terry Spivey, USDA
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Muskrat fur is soft and velvety to touch, composed of an inner layer of soft, short fur protected by a layer of long, glossy guard hair. A muskrat will be 16 to 25 inches in total length with a tail 7 to 12 inches long. The tail is a distinctive identifier of this species because it is rat like, but flattened from side to side, rather than round. An adult weighs about 3 to 4 pounds.Young muskrats reproduce after 10 to 12 months.
Groundhog
Groundhog. Photo by EIC, CC
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The groundhog typically measures 16 to 26 inches long, including a 6-inch tail and weighing 4 to 9 lbs. In areas with fewer natural predators and large amounts of food, groundhogs can grow to 30 in and 31 lbs. Groundhogs are well adapted for digging, with short but powerful limbs and curved, thick claws.
Groundhogs are excellent burrowers. They hydrate through eating leafy plants rather than from a natural water source.
One litter is produced annually, usually containing 2–6 young, who are weaned and ready to seek their own dens at five to six weeks of age.
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Beaver
Beaver. Photo by Tom Smylie, USFWS
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Beaver, the largest North American rodent, can weigh up to 100 pounds but this is unusual. The usual weights for beaver are from 35 to 68 pounds. Typical total length for this species is from 39 to 47 inches, and the large flat tail varies from 10 to 13 inches long and from 3.5 to 8 inches wide.
The large flat tail easily identifies this species. Other identifying characteristics are the hind feet which have four webbed toes and a fifth free toe that supports an articulating split nail used for grooming. The coat consists of two layers; a coarse outer layer of guard hair, often yellowish to reddish in color, and a fine dense layer of underfur.
Otter
Otters. Photo by Alan Pennington, CC
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River otters are semiaquatic mammals, known for their playful behavior. Otters are large weasel-like animals that have long bodies, small ears, a broad snout, short legs with webbed feet, and a long hair-covered tail that is wide at the body and narrows toward the tip. Adult otter can be over 50 inches long and weigh up to 25 lbs. Otter are carnivores, feeding on fish, crayfish, frogs, insects, small mammals, mollusks, and blue crabs. |