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Location Canada, Ontario
Central coordinates 82o 31.20' West  42o 24.33' North
IBA criteria A4i, A4iii
Area 140,000 ha
Altitude 174 - 176m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description Lake St.Clair, which forms part of the Great Lake system, is located in extreme southwestern Ontario to the north of the cities of Windsor and Detroit. The St. Clair River provides an inflow from Lake Huron to the north, and the Detroit River provides an outflow to Lake Erie to the south. The Eastern Lake St. Clair IBA encompasses the eastern shore, marshlands and agricultural fields from the Sydenham river at Wallaceburg to the mouth of the Thames River and the open waters of Lake St. Clair, south of the St.Clair River delta under Canadian jurisdiction. The large delta and the shallow nature of the lake result in extensive areas of marshland that is characterized by both submerged and emergent vegetation. Walpole Island, which is located within the St. Clair delta, contains some of the most significant tall grass prairie /oak savannah communities remaining in Canada.

Key Biodiversity Lake St. Clair is recognized as being one of the most significant staging areas for waterfowl in southern Ontario. During studies completed in the 1970s and early 1980s, it was estimated that peak totals of waterfowl were over 60,000 during spring migration, and over 150,000 during fall migration. The site was estimated to support 1,137,000 Canvasback and Redhead waterfowl-days, and as many as 5,123,000 dabbling duck waterfowl-days. (A waterfowl-day equals the number of ducks multiplied by the number of days present). The agricultural fields along the east shoreline also support large numbers of Black-bellied Plovers and American Golden Plovers during spring migration. As many as 5,000 Black-bellied Plovers have been reported, which could represent as much as 3.5% of the estimated North American population.

In addition to being significant as a staging area, the Lake St. Clair marshes also support significant populations of breeding birds. One of the largest breeding concentrations of Black Terns in Ontario is present, along with over 3.5 % of the estimated North American Forsters Tern population. The largest known Canadian population of King Rails (nationally endangered) has been recorded, along with significant numbers of Least Bitterns (nationally vulnerable).

The prairie and oak savannah communities of Walpole Island also support threatened bird species, with the largest self-sustaining concentration of Northern Bobwhite (nationally endangered) being present. There are also historic nesting records of Henslows Sparrows (nationally endangered), along with numerous other potential breeding records for nationally threatened species such as Acadian Flycatcher, Cerulean Warbler, Prothonotary Warbler, and Yellow-breasted Chat.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Canada Goose Branta canadensis passage  1980  378,000 individuals  A4i  Least Concern 
Tundra Swan Cygnus columbianus passage  1980  135,000 individuals  A4i  Least Concern 
Forster's Tern Sterna forsteri breeding  1991  555 breeding pairs  A4i  Least Concern 
A4iii Species group - waterbirds passage  1980-1995  100,000-499,999 individuals  unknown  A4iii   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
St. Clair Wetlands of International Importance (Ramsar) 244 protected area contained by site 640  


IUCN habitat Habitat detail Extent (% of site)
Forest Temperate deciduous woods  -
Grassland Steppe & dry calcareous grassland  -
Wetlands (inland) Freshwater lakes and pools  -
Artificial - terrestrial Arable land  -

Land use

Land-use Extent (% of site)
agriculture major
nature conservation and research major
fisheries/aquaculture minor
hunting major
other minor
tourism/recreation major

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Eastern Lake St. Clair. Downloaded from on 26/10/2016

To provide new information to update this factsheet or to correct any errors, please email BirdLife