The river otter is a member of the weasel family that inhabits parts of North America. This mammal ranges from the Deep South and up the Atlantic Coast into states such as Virginia and Maryland. The otter lives throughout New England, the Pacific Northwest, most of Alaska and in much of Canada. By familiarising yourself with how to identify the river otter's tracks, you may have the ability to trace the animal's activities.
Search for otter tracks near rivers, streams, ponds and lakes. While the otter will frequently go onto land, the creature never strays too far from the water for long periods. The main part of an otter's diet is aquatic animals such as fish and various invertebrates. Otters will travel between bodies of water on occasion, but typically do so via brooks and streams when possible. Your best chance to find otter tracks will be in mud or sand near water, or in a fresh covering of snow.
Look for tracks that feature signs of five toes on both the front feet and on the back feet. All types of weasels have this number of toes on both feet. However, as the Beartracker's Animal Tracks Den website points out, many times only four toes will show up in an otter's track. When the fifth toe of an otter does leave an imprint, it will be the smaller inner toe of the otter's foot and the toe's imprint will be further back than the other four toes are.
Measure the tracks. River otters have tracks that are about three inches wide for their front feet, and just a bit wider and longer when left by the rear feet. The New York State Department of Environmental Protection describes an adult otter's tracks as covering about the same area that the bottom of a soda can would.
Inspect the track closely to see how far apart the toes appear and if any sign of the otter's webbed feet shows up. As an otter walks or runs, its toes will fan out widely, according to the "National Audubon Society Field Guide to Mammals." In most instances, the webbing will not leave an imprint, but on rare occasions, you may be able to spot markings between the toes that indicate the webbed feet.
Examine tracks for signs of the otter's tail dragging along behind it, especially when tracking an otter in the snow. An otter's tail is heavy and it will leave a mark that looks as if you dragged the end of a stick in the snow. This mark will be between the tracks.