As the name suggests, North Arm is at the north end of Great Slave Lake, in southcentral Northwest Territories. The city of Yellowknife is on the border of the site. The site follows the north shore of the arm from Frank Channel to Franois Bay and includes the lower reaches of the Beaulieu River (north to Watta Lake) and the Yellowknife River (upstream to Prosperous Lake). The relatively shallow, north shore area has many small islands, bays and shoreline wetlands.
The north side of North Arm is an important area for northward-migrating waterfowl in spring. The site is particularly important in years with late springs (such as 1988 and 1990) when the amount of available open water is limited. In mid-May 1990, over 100,000 waterbirds of 29 species were counted at the North Arm. Of these, 20,500 were Canada Geese (about 4% of the Short Grass Prairie population), 12,000 were scaup, 5,700 were Northern Pintail, 2,050 were Tundra Swans and 1,280 were Surf Scoters. Although this high number of swans is about 1% of the North American Tundra Swan population, there are usually fewer swans present. On average 1,417 Tundra Swans were seen during the 4 years for which counts occurred. These swans are from both the eastern and western populations.
The North Arm is on the boundary of the Canadian Shield (lying to the northeast) and the Mackenzie Lowlands (on the southwest). As a result, the forests of the region are especially productive for breeding boreal ducks.
In summer, several species of gulls and terns nest on islands in the North Arm. California, Ring-billed, Mew and Bonapartes gulls breed at the site (1,300 gull pairs in 1986/7). Terns are also common: Caspian Terns (77 pairs in 1986/7), Common and Arctic Terns (300 pairs, both species in 1986/7) and Black Terns (300 juveniles in 1989) all breed here. Some of the Black Terns and Caspian Terns breed near Trout Rock.
BirdLife International (2020) Important Bird Areas factsheet: North Arm, Great Slave Lake. Downloaded from http://www.birdlife.org on 08/07/2020.