The marsh shrew (Sorex bendirii), also known as the Pacific water shrew, Bendire's water shrew, and Bendire's shrew, is the largest North American member of the genus Sorex, known as the long-tailed shrews. It is covered in primarily dark brown fur and found near aquatic habitats along the Pacific coast from southern British Columbia in Canada to northern California in the United States. The first specimen was obtained 18 mi (29 km) southeast of Fort Klamath in Klamath County, Oregon, at a location 1 mi (1.6 km) from the Williamson River. Air trapped in the fur provides buoyancy and marsh shrews are able to run for as long as 3 to 5 seconds along the top of the water. The shrew measures about 16 cm (6.3 in) in length including a 7 cm (2.8 in) long tail. Marsh shrews weigh on average 14.5–16 g (0.51–0.56 oz). They eat primarily invertebrate animals, which they hunt both on land and in the water. Marsh shrews are rare, and populations are thought to be in decline. They are listed as endangered in parts of their range. Their range in Oregon is limited to the western portion of the state.