Track Hindprint in mud 2–3" (50–75 mm) long, with all 5 toes printing; foreprint half as long, narrower, generally with only 4 toes printing (fifth toe is vestigial). Hindprint can be ahead of or behind foreprint, sometimes overlapping. Distance between sets of walking prints approximately 3" (75 mm). Tail often leaves drag mark between prints; may alternately be lifted and dropped, or held up completely, leaving no mark.
Sign Lodges and burrows: Houses, or lodges, constructed of aquatic plants, especially cattails; lodges up to 8' (2.4 m) in diameter and 5' (1.5 m) high, built atop piles of roots, mud, or similar support in marshy areas, streams, or lakes, or along water banks. Also, burrows in stream or pond banks, with entrances above water line.
Feeding signs: Feeding platforms of cut vegetation in water, or on ice, slightly smaller than houses and marked by discarded or uneaten grass and reed cuttings. Other signs include floating blades of cattails, sedges, and similar vegetation near banks or feeding platforms and piles of clamshells sometimes at feeding sites in freshwater areas.
Scent posts: Scent posts along banks, composed of small mats of leaves and grass blades mixed with mud and musk secretions.
Scat: Oval, generally 1/2" (12 mm) long pellets, frequently in clusters on rocks, along banks, on logs in or next to water, and on feeding platforms.