Wildlife of the Week!

POSTED ON JULY 12, 2020 BY ANDREW LEES

©Five Star Whale Watching/ Andrew Lees. A River Otter lounges on a dock in Victoria, B.C. River Otters are much smaller than Sea Otters while also having more mobility and agility on land.

Who is ready to test their otter knowledge? Continuing on the trend from our last Wildlife of the Week, we are going to discuss another important non-cetacean mammal that can be found in the Salish Sea. Past features of ours have focused on the Sea Otter and the Harbour Seal, both important pinnipeds in the Salish Sea. Our next highlight is not a pinniped as these two species are, however it is also not a cetacean. The animal may also be confused with the Sea Otter. 

If you’re thinking this Wildlife of the Week is a River Otter (Lutra canadensis), then you are correct! Have you seen a River Otter before? Share the location in the comments below!

The River Otter is an interesting and charming creature that can often be spotted along Salish Sea shorelines and in waterways. Measuring a maximum length of about 1.4m (~4 ½ feet) with its long tail, the animal is definitely not one of the largest aquatic mammals on the coast. This otter is much smaller than, say, a Sea Otter or Sea Lion. Contrary to the fact that they are both “Otters”, the River Otter and Sea Otter are different in several respects. Although they are both “mustelids” (includes animals such as otters, badgers, weasels, martens), they grow to different sizes, have variability in their mobility on land, swimming style and habitats. 

Adult River Otter males typically weigh in at a maximum at 30 pounds, whereas females may be found weighing within the 10-20 pound range. They are usually a fairly uniform dark brown colour with a lighter underside; their fur is sleek and water-repellent. 

The name “River Otter” can be coined as a slight misnomer in some of their range, as they can often be spotted in other freshwater sources as well as saltwater, unlike the Sea Otter which is only found in the latter. Their habitat can include coasts as well as inland regions (e.g. freshwater bodies like lakes, marshes and rivers) throughout North America. They are much more mobile on land (even with webbed feet) and can be seen spending elapsed amounts of time out of the water (e.g. sleeping, travelling, playing), unlike their Sea Otter relatives who rarely leave the sea. 

The River Otter is especially tied to terrestrial habitats in that they create land-based burrows near water, which also means that they give birth on land, unlike Sea Otters. River Otters also depend on an effective coat to keep them warm both in and out of water. 

River Otters will forage for a variety of prey types which includes shellfish and other invertebrates (e.g. clams, insects), birds, fish and even amphibians. Prey-finding is helped along by the use of their sensitive whiskers. 

The creature is not born knowing how to swim, and must learn this skill from its mother; a River Otter may dive for up to eight minutes maximum. The species does not hibernate and can even be found staying active under ice cover by breathing through small imperfections. They live about five years and reproduce typically every other year after maturity between 2 and 3 years old. 

Both varieties of otters have predators and the River Otter has to be wary of such creatures like bears, owls and coyotes. River Otters are also vulnerable to habitat loss and related issues like pollution, thus a healthy habitat has been recorded to strongly affect their population. 

Did you know these facts already? Do you know even more about the River Otter? Try out your knowledge with some trivia below! 

1. What is the offspring of a female River Otter called? (ANS: a “kit”). 
2. True or False? The River Otter has 3 layers of fur to help with water repellency and warmth. (ANS: FALSE: This Otter has TWO layers, for the respective reasons above). 
3. The River Otter has the longest-lasting fur of any otter or weasel. (ANS: TRUE).

BONUS CHALLENGE: Between a Sea Otter and a River Otter, which species has a larger litter of offspring? 

ANSWER: River Otters have more pups, usually about 2-3/litter in contrast to the Sea Otter’s 1/ litter. 

If you would like to gain some more knowledge on these adorable and fascinating creatures, check out our References below! 

Hogge,Katie. 2019. “How to Tell the Difference Between Sea Otters and River Otters.” Ocean Conservancy. https://oceanconservancy.org/blog/2019/01/30/tell-difference-sea-otters-river-otters/

Langlois, Annie. “Sea Otter.” Hinterland Who’s Who. Environment and Climate Change Canada and Canadian Wildlife Federation. https://www.hww.ca/en/wildlife/mammals/sea-otter.html. 

“River Otter.” 2020. Nature Conservancy Canada (NCC). https://www.natureconservancy.ca/en/what-we-do/resource-centre/featured-species/mammals/river-otter.html. 

“RIVER OTTER.” Sierra Club BC. https://sierraclub.bc.ca/river-otter/.