Algonquin Provincial Park Mammals of the Mixed Forest

River otters are sleek, social carnivores that forage fish and invertebrates in lakes and streams; they use dens in banks or natural cavities and are often playful. Their presence signals healthy aquatic systems in Algonquin.

Look for a long, streamlined body with short legs and a strong, tapered tail; otters slide into water, surface frequently, and often swim with head and back visible. They give chirps and whistles when social or alarmed.

Common Confusions

• Mink Neovison vison Minks are smaller and more weasel-like with a slimmer profile; otters are much larger with thick necks and long, tapered tails.
• Muskrat Ondatra zibethicus Muskrats have a laterally flattened tail and different swimming posture; otters show more fluid undulating swimming and surface dives.
• Beaver Castor canadensis Beavers are bulkier, have a paddle tail and build lodges; otters are lean with rounder heads and playful group behavior.
• Seal Seals are marine and not found in Algonquin; confusion only possible for very distant silhouettes in large lakes.
• Otter Pup Lontra canadensis Pups are smaller and may remain at den sites; adults are longer and more streamlined when swimming.