The Sutton River enters Hudson Bay in northeastern Ontario, about 90 km west of Cape Henrietta Maria. The IBA includes the bay at the mouth of the Sutton and Kinushseo Rivers, Little Cape, and the coastline eastward for about 40 km. Little Cape is a promontory that extends about 5 km into Hudson Bay on the north and east side of the Sutton River estuary. About one third of the cape consists of dry gravel ridges up to 9 m high, which are covered with low vegetation (grass and moss); the remainder is low, flat marshland. The Sutton and Kinushseo River estuaries are shallow and shoal filled. The areas adjacent to the river mouths and to the east consist of low marshy fens and dry heath lichen tundra on low beach ridges. Marshes and fens extend inland for 10 to 15 km through open tundra. The shoreline has wide intertidal marshes and submerged shoals extending for at least 1 km offshore.
The Sutton River coastline is a significant staging, breeding and moulting area for large numbers of waterfowl. During fall migration, large numbers of Lesser Snow Geese stage at this site, with a one-day count in excess of 23,000 having been recorded. Notable numbers of Tundra Swans have also been recorded at this site during the late summer, with 500 to 600 often being recorded here. Although few shorebird surveys have been completed at this site there is a record from the early 1950s of a one-day total of 700 Pectoral Sandpipers. Such a congregation would likely have been greater than 1% of the estimated North American Pectoral Sandpiper population.
Over the last ten years, Lesser Snow Geese have started to nest in increasingly large numbers in the coastal marshes from the Kinushseo River eastward for about 30 km. It is now estimated that about 20,000 Mid-continent Snow Geese breed at this site. Common Eiders (ssp. sedentaria) has also nested in significant numbers at Little Cape. Although recent population estimates are not available, it is likely that if the colony is still present it would be significant given the small population of ssp. sedentaria. Other notable bird species that breed at this site include King Eider (one of the few breeding sites for this species in Ontario), and Dunlin.
During the summer, large flocks of moulting Black Scoter have been observed; in 1994 a one-day count of 1,250 scoters was recorded, which represents about 1% of the estimated eastern North American population. Large flocks of other ducks, such as Northern Pintail, Common Goldeneye, Oldsquaw and White-winged Scoter, have also been recorded in what appear to be moulting aggregations.
Conservation responses/actions for key biodiversity
Most of this site is located within Polar Bear Provincial Park (the exception being offshore areas). No specific threats are known, although overgrazing by large concentrations of Snow Geese is a concern. Such impacts can lead to a change in the wetland structure and modification of habitats.