Site Complet

Thedford Flats (ON026)


Thedford Flats (ON026)

Grand Bend, Ontario

Latitude 43,225°N
Longitude 81,819°O
Altitude 180 - 183m
Superficie 15,57km²

Description du site

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.


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.

Enjeux de conservation

There are no primary threats facing this site because the swans are taking advantage of an artificial situation. If the farmers increase the drainage, change the pump-draining schedule, or stop planting corn, swan use would diminish.

The Lambton County Heritage Museum organizes an annual Swan Viewing Festival. This festival has increased awareness of the site, and resulted in voluntary delays in pump-draining the fields until after the swans have moved on.

Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
Cygne siffleur
Nombre Année Saison
6 000 - 18 0002021Printemps
1 900 - 2 1002020Hiver
15 000 - 33 0002020Printemps
5 000 - 10 0002019Printemps
5 000 - 8 0002018Printemps
2 000 - 3 0002017Hiver
10 2002016Printemps
3 000 - 4 0002014Printemps
3 800 - 11 5002013Printemps
5 0002011Printemps
2 0002009Printemps
10 0001998Printemps
7 0001996Printemps
8 0001995Printemps
16 3561994Printemps
13 1001993Printemps
3 3001991Printemps
10 0001990Printemps
5 0001989Printemps
3 8001988Printemps
8 0001987Printemps
8 0001986Printemps
2 8191985Printemps
1 5001984Hiver
10 0001983Printemps
5 5001977Printemps
Mouette pygmée
Nombre Année Saison
3 - 42020Printemps