Northern River Otter, Lutra canadensis
Common Names: Northern River Otter, North American River Otter
Species: Lutra canadensis
General Description The northern river otter is a large mustelid, the males often attaining a body length of about 70 cm (120 cm including the tail), and females somewhat smaller (up to about 60 cm, tail excluded). River otters generally weigh between 5 and 13 kg. They have thick, dark brown fur with a silvery sheen on the underparts. River otters are highly adapted for their aquatic lifestyle. They have streamlined bodies with short, powerful legs and webbed feet, as well as valved nostrils and ears which prevent water intake. Oils secreted by skin glands are smoothed over the coat, rendering it waterproof. Northern river otters mark locations within their waterfront territories with feces, urine, and anal gland secretions. These so-called “latrine sites” may be 5-20 m in radius, and are thought to mark feeding sites, and perhaps function as indicators of social dominance.
Geographical Distribution and Habitat Requirements The northern river otter is widespread in New Brunswick, and is generally seen along stream and lake shores as well as in salt marshes. They are highly aquatic, but will travel considerable distances over land to seek water. The otter can be found throughout much of North America, from Newfoundland to South Carolina on the east coast, and from Alaska to northern California on the west.
General Biology Throughout the year, the diet of the northern river otter consists mainly of fish, particularly slow-swimming species. Aquatic crustaceans, amphibians, ducks, and occasionally muskrats (Ondatra zibethicus) may also be consumed by this primarily nocturnal hunter. When swimming in deeper waters, the otter often strikes prey from below, using vision when conditions are suitable. River otters also use their sensitive vibrissae to locate prey, usually ion shallow water. Scent is the primary mode of communication between individuals; each otter has a distict odour from which other individuals can determine information such as sex and reproductive state. River otters are fairly social, and they will frequently travel, forage, and engage in play behaviour in groups of two or more. However, individual otters have large home ranges (20-40 km along banks, although ranges do overlap) in which their water dens, or burrows in stream banks, are located. Males tend to have larger territories, and usually associate with females only for breeding which takes place in March and April. As with many mustelids, the females may delay implantation of the blastula for as long as nine months. Gestation period is around 60 days, and a single litter of 2-4 blind and helpless pups are born in February to April. In four to six months, the young acheive independence. Northern river otters have an average life span of about 9 years in the wild.
Conservation River otters are not listed as threatened by the IUCN. Although both air and water pollution have taken a toll on the northern river otter population, there has been an increase in numbers in recent years, and they are currently considered to have a stable population in New Brunswick. However, the river otter has been driven to extinction, primarily by trapping, in many parts of the American midwest, as there is a market for their dense and durable pelts. River otter trapping is permitted in New Brunsick.