This site is on the north shore of the St. Lawrence River, near the village of Baie-Ste-Catherine. It consists partly of extensive tidal flats, which are flooded by strong tides, and partly of the adjacent deeper water at the mouth of the Saguenay River (embouchure de Saguenay). Except for a small forested area, the Batture aux Alouettes is defined by the mean high and low tide levels. The Spartina alterniflora marsh is one of the rare salt marshes of the north shore. There is one small island in the site which has sparse grassy vegetation. The shoreline is steep and mostly covered with mixed woods.
The avifauna of the batture is mainly characterized by flocks of migrating shorebirds - it was identified as a potential Western Hemisphere Shorebird Reserve Network regional site. The high numbers found are very likely an underestimation since the mudflat is 5 km wide in places, making precise counts difficult. Although the highest total count is 8,632 in 1989, it is probable that this site’s shorebird flocks meet the national threshold of 10,000. Three species, however, are definitely present in significant numbers. As many as 1,600 Red Knots were tallied in one day, representing over 1% of the North American population. Sanderling has the highest one-day count of any individual shorebird species, with 2,800 recorded in 1989; this accounts for over 1% of the global population. Finally, Purple Sandpiper has been recorded in winter in significant numbers: 120 birds were recorded in the winter of 1999. Other regular shorebirds include Black-bellied Plover (600 in the fall of 1989), Ruddy Turnstone, Dunlin (2,000 in the fall of 1989), Baird’s Sandpiper and Pectoral Sandpiper.
There are notable numbers of waterfowl in several seasons. Diving ducks are common in the mouth of the Saquenay in winter. Barrow’s Goldeneye (nationally Special Concern) is recorded in high numbers. In 1999 150, or 5% of the eastern population were recorded and earlier in 1978, 500 were counted. Oldsquaw are often seen in very high numbers, with a peak count of 25,000 in 1978, and 15,000 in 1991. Common Goldeneye are also abundant. In the fall, the area is regionally important for waterfowl, particularly dabblers. Occasionally, the nationally endangered eastern Harlequin Duck is recorded in this season. In the summer, an average of 915 Common Eider nests were recorded between 1992 and 1996. This is just over 1% of the North American S. m. dresseri population.
Other breeding birds include three colonial species: Double-crested Cormorant (4 year 1987-1999 average of 868 nests), Great Black-backed Gull (303 nest in 1999) and Herring Gull (120 nests in 1999). Since 1988, there have been nesting Bald Eagles; one of only 40 known nesting sites in the province. Up to two nests have been found in the forested part of the site. High numbers of another larid have been recorded in the fall. In 1993, 4,500 Black-legged Kittiwakes were counted.
In spring migration, Snow Buntings, Lapland Longspurs and Horned Larks can be numerous while a few Northern Harriers and Short-eared Owls (nationally Special Concern) often stop to hunt.
BirdLife International (2020) Important Bird Areas factsheet: Batture Batture aux Alouettes and mouth of Saguenay River. Downloaded from http://www.birdlife.org on 27/02/2020.