Anderson River Delta

Country/territory: Canada

IBA Criteria met: A1 (2001)
For more information about IBA criteria please click here

Area: 76,000 ha

Birds Canada / Nature Canada

Site description
The Anderson River IBA follows the lower 50 km of the Anderson River and includes most of Wood Bay, on the north coast of Northwest Territories. A nearby, but unconnected, piece of land - the lower 20 km of the Mason River is also included. The land is low-lying, but not completely flat, and sits on Cretaceous sedimentary rock. Lakes and ponds are common in the surrounding area and the river breaks up into several channels at the delta.

At the highest reaches of the site the surrounding land is spruce forest, Dryas tundra is found a little farther down, and at the river delta the vegetation is made up of grasses, sedges and willows. Part of the river delta was a glacial refugia in the last ice age and thus some plants and insects found here show an unusual distribution.

An Inuit community was once supported by the abundant wildlife; remains of this community can still be found in places. Barren-ground Grizzly are common and both Caribou and Moose are seen at this tree-line site.

Key biodiversity
Many species of waterfowl use the Anderson River for breeding, moulting and staging. The western subspecies of Brant (nigricans or Black Brant) breed in the outer delta. About 2% of the Black Brant population, or 2,500 birds, are here from late May through to August or September. An additional 100 Brant breed on the Mason River. A second species of waterfowl, the Tundra Swan, breeds here in small numbers, but significantly more (1,200 or over 1% of the eastern population) stay to feed and moult in summer.

Other goose species are common in the area. In 1995, at least 3,600 Lesser Snow Geese of the Western Central Flyway population bred on the islands at the mouth of the Anderson River. Several hundred of these Geese bring their broods over from the Anderson River to the Mason River. Both the Anderson and Mason river deltas support about 1,000 moulting Greater White-fronted Geese.

Numerous other birds breed, moult, and stage in the area. Large numbers of Oldsquaw, scaup, scoters, dabbling ducks (3,000 5,000), shorebirds, raptors and songbirds are all found in the delta. The Mason River also supports 50 pairs of Glaucous Gulls.

The Eskimo Curlew used to breed here. This shorebird is globally listed as critical and nationally listed as endangered, but may now be extinct. The bird was last seen somewhere along the Anderson River in 1989.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Anderson River Delta. Downloaded from on 19/08/2022.