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Location Canada, Ontario
Central coordinates 81o 49.35' West  43o 13.53' North
IBA criteria A4i
Area 1,000 ha
Altitude 180 - 183m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description The Thedford Flats are located near the Lake Huron shoreline in northwest Lambton County, about 10 km north of Thedford, and 10 km south of Grand Bend. Pinery Provincial Park borders the west side of the site. At one time this area was a shallow bay and marsh that was cut off from Lake Huron by the formation of 30 metre high dunes on the east side of what is now Pinery Provincial Park. In 1875, a canal was cut through the dunes to drain the marsh, and the last remnant (Lake Smith), was drained circa 1959. At present, the flats must be drained with pumps in the spring. Potatoes and onions have been grown here, but in recent years the crops were primarily corn and beans.

Key Biodiversity Since at least 1970, Tundra Swans have congregated at the Thedford Flats during late March. Peak one-day counts have been recorded regularly since the early 1980s, and the long-term average (1983 to 1998) is just over 7,600 birds. A more recent average (1993 to 1998) is 10,800 birds, which is almost 6.5% of the North American Tundra Swan population, and about 12.5% of the estimated eastern population. The maximum one-daycount was recorded in 1994, when 16,356 birds were tallied. Since these one-day counts consider turnover rates, he number of swans moving through the site during the entire spring migration is likely much larger.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Tundra Swan Cygnus columbianus passage  1998  10,000 individuals  A4i  Least Concern 


IUCN habitat Habitat detail Extent (% of site)
Artificial - terrestrial Arable land  -

Land use

Land-use Extent (% of site)
agriculture major

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Thedford Flats. Downloaded from on 22/10/2016

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