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Solano County Office of Education

Solano County Office of Education

North American river otters (Lontra canadensis) are mammals with long, slender bodies, long whiskers, short legs, webbed feet, and thick, powerful tails. They have two layers of fur to keep warm as they swim in cold water. Their fur is usually dark brown over most of their body and lighter brown on their underbelly and face. Their outer layer of fur has an oily coat that helps repel water and glide better. 
Adult river otters can weigh between 10 – 30 pounds and grow to between 2.5 – 5 feet tall (approximately as long as an elementary school student is tall). Their tales are about one-third of their total length. Female North American river otters are smaller than their male counterparts and grow to approximately one-third the size of males. Due to the shape of their bodies, webbed feet, strong tails and oily fur the otters are strong swimmers.
North American River Otter


North American River Otter Range Map
North American river otters can be found across the United States and Canada, as well as right here in Solano County in the Suisun Marsh. These river otters have also been spotted in Putah Creek below Lake Berryessa and all the way to the Yolo Bypass near Sacramento. North American river otters tend to live in similar habitats as beavers, primarily in riparian zones, the interface between land and water. They prefer to live in freshwater, however, they are also found in brackish water systems, both marine and freshwater, near streams, rivers, lakes, ponds and marshes. These river otters are adaptable to hot and cold climates as well as low coastal waters and those in high elevations. 


river otter tracks
Photo credit: TaviEllis, CC BY-SA 3.0
via Wikimedia Commons
You may see evidence of river otters by finding their tracks.  You can see which way they're going and where they came from.  Their footprints are five toes with webbing and claws. You are more likely to see the claws than the webbing unless the print is in the mud where the imprint may be more defined. 
You might also find evidence of their “slides” near the banks of the river as they slide into the water.  


North American river otters play an important role in our ecosystem. River otters are predators which means they help control the populations of the food in their diet. They rely on abundant fisheries and small animals to maintain their health and their presence in our watershed means the ecosystem is likely healthy. This is important because as top predators they help maintain a balance in the food web and if the river otters are leaving it may indicate there is something wrong with the water quality that affects their diets.  


North American river otters use their long whiskers to sense their prey in the water. They aren’t too picky and eat a variety of food from the water including crayfish, crabs, frogs, fish, bird eggs, turtles, and clams. They may also eat some plants that grow in the water and other small animals such as rabbits. 


The River Otter Ecology Project.
You can become an Otter Spotter and report your sightings at The River Otter Ecology Project.
The River Otter Ecology Project is collecting data from the community. You can upload your otter sighting images to their page.  This contribution provides observation data and tracking of the North American river otters in California and across the United States.