The Saint-Timothée marsh borders the north side of the Canal de Beauharnois roughly 25 kilometres to the southwest of Montreal. The Canal de Beauharnois is another IBA and a branch of the St. Lawrence River. The Saint-Timothée marsh is a dammed section of marsh and pond managed by Ducks Unlimited (Canards Illimités). Much of the surrounding land is agricultural.
The Saint-Timothée marsh hosts a rich diversity of marsh birds and other water birds. Most notable are post-breeding season Great Egrets, and breeding Least Bitterns and Black Terns, all of which are found in nationally significant numbers. Sixty-five Great Egrets were been counted here in the summer of 2000. This is roughly 10% of Canada’s growing Great Egret population. A partial survey in 2000, revealed that at least 10 pairs of Least Bitterns bred in the marshes. This is about 1% of the Canadian population of this nationally vulnerable species. Using extrapolation, it is estimated that 15 pairs may breed in the whole of the marsh. Black Terns are another marsh breeder found in significant numbers – 100 were counted in 1998.
After the breeding season, immense numbers of swallows and blackbirds sometimes arrive in the marsh. On one occasion 100,000 Tree Swallows were counted, and on another 800 Bank Swallows. The swallows roost in the shrubby trees that are resprouting from large stumps that are sprinkled throughout the site. Little islands of Phragmites attract migrant blackbirds in both fall and spring. A maximum count of 10,000 Red-winged Blackbirds was recorded in 1996. Thousands of Starlings and smaller numbers of Brown-headed Cowbirds and Common Grackles flock together here during migration.
Geese are also abundant migrants. Maximums of 8,500 Canada Geese in the spring and 6,000 Snow Geese in the fall have been recorded. Numerous species of ducks feed here in both migration seasons - species include: Mallard, American Widgeon, American Black Duck, Gadwall, Wood Duck, Blue-winged Teal, Green-winged Teal, and Ring-necked Duck. Small numbers of Northern Shovelers and Redheads breed here. This is one of the few locations in Quebec where the latter species breeds regularly.
Other breeding birds include American Coot and Great Blue Heron, while some of the post-breeding birds occurring here are Pied-billed Grebe, Black-crowned Night-Heron, and Common Moorhen.
BirdLife International (2021) Important Bird Areas factsheet: Marais de Saint-Timothée. Downloaded from http://www.birdlife.org on 26/02/2021.