The Saint-Étienne marsh borders the south 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-Étienne marsh is an artificially created marsh, surrounded mostly by agricultural lands. A large hydro line cuts through the middle of the site.
About 90 waterbird species and 81 other bird species have been recorded in the Saint-Étienne wetlands. Not well known, but most significant are the numbers of post-breeding Great Egrets, Black-crowned Night-Herons and breeding Black Terns. In 2000, 32 Great Egrets were counted here in the summer. These numbers are equivalent to about 5% of the Canadian population of Great Egrets. About 90 post-breeding Black-crowned Herons were seen in 1999 (about 1% of the Canadian population). Precise counts have not been made, but about 200 breeding Black Terns were recorded in the 1990s. Another interesting breeding species is the Least Bittern. Four birds were recorded in 1992.
This location is better known as a good Montréal area birding spot and an excellent place for migrating waterfowl and blackbirds. Many species of waterfowl are abundant in the fall, and many of the same species are also common in the spring. Amongst the most common, in decreasing order of abundance are: Mallard (highest count of 3,000), Snow Goose, American
Wigeon, Ring-necked Duck, American Black Duck, Green-winged Teal, Northern Pintail, and Northern Shoveler (a high count of 150 in the spring). There can be high densities of Pied-billed Grebes and Common Moorhens in the ponds here; up to 400 grebes and 69 moorhens have been counted.
Immense numbers of blackbirds and Starlings were formerly seen here. Flocks of birds numbering well into the hundreds of thousands used to roost here in the beds of Phragmites. Red-winged Blackbirds and Starlings dominated the flocks - up to a half a million of each species were seen in the early 1990s - but Common Grackles and Brown-headed Cowbirds were also extremely common. In recent years, Phragmites control measures have been taken, which has noticeably reduced the numbers of blackbirds. Now, the flocks number in the thousands.
BirdLife International (2020) Important Bird Areas factsheet: Marais de Saint-Étienne. Downloaded from http://www.birdlife.org on 26/09/2020.