Located on the south shore of the St. Lawrence River estuary, this IBA lies in front of the town of Montmagny, at the mouth of the Sud River, about 70 kilometres east of Quebec City. Most of the area is a brackish tidal wetland. Sedimentation at Montmagny Bay has resulted in the formation of extensive mud flats, while scirpus salt marshes are found on both sides of the Sud River. Other aquatic plant communites are dominated by bulrush but include Wild Rice and several species of arrowleaf. The herbaceous vegetation is comprised of a variety of species such as Giant Bulrush, Giant Bur-weed, Cord Grass, Smoke Weed, Purple Loosestrife and other grasses and sedges. American Shad can be found in the salt marsh, while American Eel migrates to the south in the St. Lawrence estuary.
The most noteworthy species found at Montmagny is the Greater Snow Goose (subspecies atlanticus). The greatest numbers are present in fall migration when at least 5,000 birds are regularly present (about 1% of the subspecies' population). In some years, however, much higher numbers can be recorded, such as in 1997, when a flock of 50,000 were seen. typical numbers?
In 1977, 125 Black-crowned Night-Herons were counted, but the colony seems to have declined since then. Of the many shorebirds that occur here, only Semipalmated Sandpiper has been seen in significant numbers, with over 15,000 counted in the fall of 1980. More recently in 1990, 11,900 were recorded. The second most common shorebird is the Lesser Yellowlegs, with maximum counts of 250 birds. Other regular shorebirds are Greater Yellowlegs, Semipalmated Plover, Killdeer, White-rumped Sandpiper and Least Sandpiper.
Surveys over the years have recorded numerous dabbling ducks, with the commonest being Northern Pintail (maximum count of 3,500). Other common species are Green-winged Teal, Common Eider and Greater Scaup, while American Black Duck, Mallard, Blue-winged Teal, Oldsquaw and Ring-necked Duck occur in smaller numbers. The salt marsh of Montmagny is part of a section of the St. Lawrence estuary that was classified as a waterfowl concentration area.
Four species that are nationally at risk have been sighted here, albeit in low numbers: Harlequin Duck (endangered eastern population), and Short-eared Owl (Special Concern), Red-shouldered Hawk (Special Concern) and Peregrine Falcon (Special Concern). In addition, Least Bittern (Special Concern) is present during the summer in the freshwater marsh, suggesting that there might be a nesting pair.
Since 2010, erosion problems are a growing threat to the Pointes-aux-Oies area. Each winter, the ice cover over tidal flats is diminishing, thus reducing its protective effect. The problem appears to be more acute in the airport area. An abandoned dumping ground near the site is a potential source of contaminants. In 1989, a study showed high levels of zinc, chromium, and mercury, which may be related to the dumping ground; in general, the sediments in this part of the estuary are contaminated. The Montmagny Migratory Bird Sanctuary comprises about half of the site, while additional areas are identified as No Hunting Zones (this designation relates to Snow Geese only). In the fall almost all the Snow Geese are in the sanctuary and other No Hunting Zones, whereas in the spring the geese are more dispersed. The IBA includes a Periodically Flooded Area and two areas are designated as Wildlife Habitat - Aquatic Birds Concentration Area (activities leading to habitat modifications are restricted). The IBA is also part of the Sud-de-l'Estuaire Priority Intervention Zone and it was identified as being a potential regional Western Hemisphere Shorebird Reserve Network site.
The bulrush marsh is the typical coastal habitat in the region. While the water has in this region a low salinity, tides are still present and reshape continuously the river landscape. Several species, such as the rainbow smelt (population of south shore of the St. Lawrence middle estuary) and Atlantic tomcod exploit the shallow waters of the area. Many migratory species (anadromous and catadromous) are also found in the area. In addition to the two species mentioned above, we found also the American shad, the Atlantic sturgeon and the American eel, all three species being prized for their tasteful flesh.
However, several sources of pressures are threatening both the quality and the availability of aquatic habitats. The expansion of agriculture, the residential development, the creation of new resorts and artificialization of the shoreline represent significant habitat losses. The presence of major obstacles may impede the movement of fish toward their breeding site. Finally, the maintenance of the Seaway for commercial navigation (dredging and the discharge of sediments) reduces the water quality and may cause the destruction of spawning sites. The decrease of the Atlantic sturgeon population of in the St. Lawrence can be assign to this aspect. Because of habitat alteration, high exploitation of commercial and recreational fisheries and non-compliance, the population of striped bass in the estuary of the St. Lawrence disappeared around 1968. In 2002, Quebec government has established an important reintroduction program to rehabilitate the specie. Between 2002 and 2007, more than 6 300 striped bass and 6,5 millions larvae were introduced into the St. Lawrence river. A network monitoring incidental captures has been implemented in 2004, allowing to document the evolution of the population.
30,000 fry and more than a thousand individual larger than 35 cm were introduced into the St. Lawrence. In early summer 2006, over one million . From 2008, up to 50 000 fry are introduced annually over a period of 10 years. The objective of this program is to rehabilitate the striped bass population of the St. Lawrence.
Major species present:
Rainbow smelt (population of south shore of the St. Lawrence middle estuary)
Coastal habitats of this area are soaked by generally turbid and lightly salted water. We found mostly brackish marshes, dominated by American bulrush, sessilefruit arrowhead and broad-leafed arrowhead. With there large root system, theses plants retain the soil in place, helping to protect the banks against coastal erosion. In addition, the underground parts are used as a food source by the snow geese during their migrations.
The destruction and loss of habitat (shoreline fill, draining wetlands, urbanization) are the main threats affecting this ecosystem. Water pollution and the risks of oil spills are issues of concern. The spread of invasive species is to be monitored. This region is hosting 18 endemic plant species, including three endangered species in Québec.
Major species present :