Learn What to Look For
North American River Otters (Lontra canadensis) are brown with a paler throat and chest, they are dark and sleek when wet and fluffy when dry. When swimming river otters move with a side-to-side undulating motion that looks different than the straight-line swim of beavers. On land otters tend to lope or sometimes bound, so that they appear to be bouncing up and down as they go. The best times to spot river otters are around dawn and dusk when they are most active. Do not approach otters, it causes them stress and can be dangerous, especially if you are in the water too. Please send us photos of otters, especially pictures of faces, your image could help us recognize individuals.
River otter scat are called "spraints", which are usually found in groups at latrines. Otter scat is typically cylindrical when fresh and about 2cm in diameter with visible animal prey remains. The most common visible prey in our region seems to be crayfish (crawdads) entire spraints are often composed of their exoskeletons. Other frequently seen prey items are fish (blackish spraints with scales and tiny bones), birds (especially coots), and insects. River otters also produce a greenish or clear jelly-like substance without any prey remains. Spraints of all types often have astrong fishy smell, but to avoid inhaling parasites, don't go in for a sniff.
River otters create latrines, sites where multiple otter spraints can be found. Often shared by a social group, latrines tend to have a mix of fresh and old scat, trampled vegetation (if any), and a characteristic fishy otter-odor. Latrines are usually located at the water's edge near feeding sites or slides, the quantity of nutrients released on the site can cause the vegetation to brown. Latrines are also frequently associated with a prominent object such as large logs or rocks which are used as marking platforms. Photos of any latrines you find will help us locate them for further study.
River otters have five toes on both their front and back feet, although all five are not always visible, especially in front tracks. The combination of claw and toe-pad creates sharp tear-drop shaped toe impressions that generally do not connect to the U-shaped metacarpal pads (palms) or only do so lightly with the toe-tips looking much rounder and deeper than the toes. The 5cm wide, webbed hind-tracks are the easiest both to find and recognize, even when the webbing is not discernable, the tear-drop toes line up to form distinctive "candy cane"-shaped lines. Sometimes with otter tracks (and other weasels as well), the toes are all you see. Though slightly smaller, raccoon and beaver tracks are sometimes mistaken for otter they can both be distinguished by having long pointy toes that connect solidly to broad metacarpal pads.
River otter slides are trails on land that often are actually slid on if steep enough. Slides usually connect two waterways at their closest overland point or in locations with especially good cover, the can also lead to latrines or resting areas. Slides can be difficult to distinguish because they are often shared with other animals. The only way to be sure a 7-12cm wide wildlife trail is used by otters, is if it is associated with other sign.
River otters will dig shallow spaces, called "holts", out of river banks or levees, especially within the roots of large trees or beneath thick vegetation. Sometimes otters will expand the burrows of other bank-dwelling animals. Holts are thought to be used for cover and to provide shelter for otter pups; they also occasionally contain sparse beds made of vegetation. These hidden spaces are a bit of a mystery, please let us know if you spot one or any other otter sign.
Send photos to: firstname.lastname@example.org
Most of these images are from Kim Cabrera, you can learn much more about river otter sign on her website bear-tracker.com