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Location Canada, Ontario
Central coordinates 82o 35.77' West  55o 8.08' North
IBA criteria A4i, A4iii
Area 100,000 ha
Altitude 0 - 10m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description 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.

Key Biodiversity 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.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Snow Goose Anser caerulescens breeding  1997  280,200 individuals  A4i  Least Concern 
Brent Goose Branta bernicla passage  1982  20,000 individuals  A4i  Least Concern 
A4iii Species group - waterbirds breeding  1997  100,000-499,999 individuals  unknown  A4iii   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Polar Bear Provincial Park 2,355,200 protected area overlaps with site 34,000  
Polar Bear Provincial Park Wetlands of International Importance (Ramsar) 2,408,700 protected area overlaps with site 31,000  


IUCN habitat Habitat detail Extent (% of site)
Grassland Tundra  -
Wetlands (inland) Intertidal mud, sand or salt flats; Salt/brackish marshes  -
Sea Open sea  -
Coastline Sea cliffs and rocky shores  -

Land use

Land-use Extent (% of site)
not utilised major

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Cape Henrietta Maria. Downloaded from on 28/10/2016

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