River Otter

River Otter

THE SPECIES: Lutra canadensis yukonensis 

We delight in our image of the otter as a playful, social animal that enjoys sliding down mud banks and snow slopes in a manner that resembles some of our own recreations. But this behaviour is typical of immature otters only. Adults slide and push themselves along snow and ice as a rapid mode of travel, but rarely slide downhill repeatedly in play. The streamlined body that works so well as a toboggan is most efficient in the pursuit of fish.

DISTRIBUTION

Population studies have not been conducted in the Yukon, but it is thought that the otter is widely distributed in low numbers across the forested parts of the territory. Densities are probably highest in the salmon bearing Yukon River system, and in other places where fish are abundant. A few otters may inhabit the North Slope river valleys that run down to the Arctic coast.

Since otter habitat must include waterways of sufficient size and depth to support good fish populations, the range of this species in the Yukon is generally confined to the larger river systems including their lakes.

CHARACTERISTICS

As the most aquatic member of the weasel family, the otter is well adapted to an amphibious life. The seal-like shape of its long streamlined body and tapered tail is well suited to swimming. Its small eyes and ears are located high on the head, allowing it to remain low in the water. The ears and transparent eyelids close up when the otter submerges.

Underwater propulsion is provided by repeated kicks of its webbed feet and a serpentine swimming action. The otter can travel hundreds of yards underwater and remain submerged up to four minutes at a time. In clear waters during daytime, it uses its vision to locate fish; in murky or nighttime waters, its stiff sensitive whiskers help to locate and capture prey.

Rough knobs on the otter's rear heel pads give it good traction on ice. While short legs help to create a streamlined shape, they result in the characteristic hump-backed gait on land.

The sub-species of otter that inhabits most of the Yukon is darker in colour than southern sub-species and has a longer, thicker pelage. The dense underfur is whitish grey near the skin and dark brown on the tips. The long, stiff, glossy guard hairs are also dark brown. Additional underwater insulation is provided by air bubbles trapped in the fur.

River otter weights vary between five and fifteen kilograms, with males weighing more than females.

LIFE HISTORY

When temperatures rise and the snow begins to melt in April, a pregnant river otter moves to a small pond away from the main waterways and begins to search for a den. Otters do not dig their own dens. Instead, they use abandoned beaver bank dens or lodges, the burrows of other animals, or natural cavities.

In early May the otter gives birth to usually two or three pups, although litter size can vary. Averaging five ounces at birth, the silky black pups grow rapidly until they emerge from the natal den in July.

Shortly after the females give birth, otters enter their breeding period . Females breed for the first time at two or three years of age, but males do not breed until about six years of age. Copulation normally takes place in the water, away from the natal den. Like most members of the weasel family, female otters undergo a process known as delayed implantation. This means that the embryos lie dormant in the uterus for several months and do not begin to develop until the following winter.

Otters are more social than other members of the weasel family. A mother and her young form the core of the family group which sometimes includes the father. Batchelor groups of males and other combinations of sex and age groups may also occur. Such flexibility probably allows otters to exploit habitats with seasonal concentrations of foods like spawning fish.

By August, the young otters are weaned and mobile. The family is able to leave the den site and move to an area of abundant prey.

The otters is highly specialized in its feeding habits. Fish, its main food source, are seized in their hiding places or caught in direct pursuit at which the otter excels. It also forages along river bottoms for aquatic insects and freshwater mussels, and occasionally consumes ducks, youn beaver, marsh birds, muskrats, voles and shrews.

By October, the young otters are able to survive on their own but will likely remain with the family through the winter. Just before the birth of a new litter, the pups disperse in search of their own hunting and foraging areas.

As winter approaches, otters that have occupied headwater streams for the summer may descend to the larger mainstem waterways of the low valleys. Otters are active all winter, fishing under the river ice and popping up for air in the gap between water and ice, and in open water areas. They frequently travel long distances under ice shelves and overland between open water areas. During severe weather they may take shelter for a few days in natural cavities among tree roots and log jams.

OTTERS AND PEOPLE

Yukon First Nations considered the spirit of the otter to be one of the most powerful characters in the animal world. Before the arrival of commercial trapping, people did not kill otters as it was considered bad luck to do so. The Tlingit believed that people who drowned turned into otter men. Because of its power, the otter was a favourite spirit helper of shamans.

Otter pelts are extremely durable and are commonly used to make men's coats. Yukon trappers, however, do not usually target otter. Fewer than 50 otter are trapped in the Yukon each winter, and many of these are caught accidently in beaver traps.

In southern Canada and the U.S., some otter populations have been wiped out by polluted waterways. Yukon populations are largely unaffected by water pollution at this time. Proper waste management practices will ensure that this situation does not change.

VIEWING OPPORTUNITIES

Otters are not abundant in the Yukon and are seldom seen by the casual observer. Canoeists paddling remote waterways, with interconnected marshes, meandering streams, and small lakes are most likely to see this amphibious mammal. Power boaters in more accessible areas may also be fortunate enough to catch sight of the otter.

In winter, good viewing opportunities will exist near open water areas.