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Otters in our midst – Lutra canadensis

River otters are one of 11 species of mustelid carnivores in British Columbia, the others being weasels (three species), wolverines, skunks (two species), martens, fishers, badgers, sea otters and mink.



By Karl Ricker,

Whistler Naturalists

Only the otter and mink depend upon water for locomotion, cavorting, play and food sources, although they sleep and loaf on land.

The river otter is very abundant along the coastline, found in salt, estuarine and freshwater lakes, rivers and creeks entering the ocean. The Squamish estuary is a dependable spot to seem them, and when the salmon are running they are there in spades to feast upon the spawners and their smolting progeny.

Fish is their main diet, and hence they are constantly marauding fish farms and hatcheries. Otherwise the marine dwellers will resort to crabs for a meal.

Inland, the mammologists regard otters to be rare. In fact, a noted authority, Dr. Ian McTaggart-Cowan, often visited the Whistler area from the 1930s to 1950s and apparently never saw one or heard stories of trapped specimens.

In that era there was a mink farm at Nicklaus North, which was likely the main source of the only aquatic mustelids in our waterway. It would be interesting to review old trapping records to see what was collected in Whistler’s pre-ski resort days.

Certainly the rodents (beaver and muskrat) would be the dominant trapped animals from the waterways, and both are abundant at present.

In fact in my recent sightings of otters those with me who were unaware of otters were misidentifying them as muskrats. But there are easy ways to tell them apart, even while swimming. Otters are twice the size of the half-metre long muskrat (including the tail). The muskrat’s tail (20 to 30 cm in length) is somewhat scaly and flattens from base to tip, whereas the otter’s tail is similar to a thick rope, perfectly round but tapering to its tip, reaching a length of 40 to 50 cm. The tail of the otter is exposed as a sinuous arc when the animal dives below the surface. Otherwise, while swimming on the surface, the larger head of the otter protrudes above, creating a noticeable bow wave. The muskrat’s head is below the surface with only its nose above and the generated wave is a mere ripple.

Finally, the head of the otter, with its short pinnate ears, resembles a pup seal when protruding above the surface, and hence great confusion when looking at marine mammals at the Squamish estuary – until they dive, the tail providing the identifiable clue.

River otters are divided into two or three subspecies in British Columbia. Those of the marine area, L.c. pacifica , are found on Vancouver Island and throughout the mainland coastal area, including lakes and tributaries of the lower Fraser River Valley, and as far north as Prince Rupert and beyond.

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