This is a large semiaquatic rodent that has been introduced to the Northwest and is considered invasive as it is very destructive feeding and burrowing behaviours. Notice the large rear claws in pic 3.
Spotted in a slough at the Ridgefield National Wildlife Refuge. Besides breeding quickly, each coypu consumes large amounts of vegetation. An individual consumes about 25% of its body weight daily, and feeds year-round. Being one of the world's larger extant rodents, a mature, healthy coypu averages 5.4 kg (12 lb) in weight, but they can reach as much as 10 kg (22 lb). They eat the base of the above-ground stems of plants, and often dig through the organic soil for roots and rhizomes to eat. Their creation of "eat-outs", areas where a majority of the above- and below-ground biomass has been removed, produces patches in the environment, which in turn disrupts the habitat for other animals and humans dependent on marshes. Coypus are found most commonly in freshwater marshes, but also inhabit brackish marshes and rarely salt marshes.