Cape Henrietta Maria juts into Hudsons Bay at the northwestern tip of James Bay. This site includes the offshore islands, shoals and associated marshes stretching 40 km west from Cape Henrietta Maria to Wabusk Point and Little Bear Island. These wide intertidal marshes and shallow shoals along the coast extend 5 to 6 km offshore. Expansive mudflats and shoals surround Little Bear Island, which is located about 5 km from the coast. Inland areas contain some of the most extensive coastal marshes on the Hudson Bay coast. The area is peppered with numerous small lakes, potholes and grassy marshes, interspersed with at least 10 km of drier heath lichen tundra on old beach ridges.
The terrain of the cape consists of bare limestone ridges in the northernmost part, and sparse grasses and sedges interspersed by small ponds and lakes. The site is an important summering area for Polar Bears; about 200 bears or 30 to 40% of Ontarios summering bears are found here.
Cape Henrietta Maria and its associated rich wetlands and marshes attract large numbers of waterfowl and shorebirds. The largest breeding colony of Lesser Snow Geese in Ontario is located here; approximately 280,200 geese congregate each summer. This colony represents 9.3% of the Hudson Bay (Mid-Continent) population. At least 15% of the entire Atlantic Brant population, or 6% of the North American Brant population, use Cape Henrietta Maria for staging during spring and fall migration. Over 20,000 birds have been observed in one-day counts during both migration periods.
Some of the provinces highest breeding densities of several waterfowl species (American Black Duck, Common Eider, and Northern Pintail) occur at this site. This site also has the distinction of being one of few places in Ontario where a small number of King Eiders nest.
During spring migration over 1,000 Pectoral Sandpipers have been recorded here in one day, exceeding the global threshold. Many other shorebirds are known to use the area, but there is little available data to indicate the numbers present.
BirdLife International (2022) Important Bird Areas factsheet: Cape Henrietta Maria. Downloaded from http://www.birdlife.org on 26/11/2022.