Île Blanche is an island that is situated 10.5 km from Rivière-du-Loup, and 2.4 km off the northeast point of Île aux Lièvres, approximately midstream in the St. Lawrence estuary, Québec. Île Blanche is a low-lying shale island that supports 4.5 ha of vegetation. A mature forest of White Spruce and White Birch, which covers most of the island, has been thinned out considerably through the death of many trees. This was caused by both great numbers of tree-nesting birds and by small scale lumbering operations in the early 1960's. The forest is encircled by a narrow belt of grass and shrubs. At low tide, the island is surrounded by extensive flats composed of sedimentary rocks dotted with tidal pools. The mean tidal amplitude is about 3.5m and the mean annual temperature is 3°C.
A very large colony of eiders is found on Île Blanche. Between 1965 and 2000, the island was surveyed for nesting Common Eider on twenty-two occasions. An average of 2,665 nests was recorded, representing about 1% of the North American breeding population, or about 3% of the Atlantic (ssp. dresseri) population of this species. The highest number recorded was 4,832 nests in 1984 and the lowest was 1,332 nests in 1995. The density of Common Eider nests is quite high at 844 nests per hectare.
In addition to sea ducks, this site is important during the fall for migrant shorebirds; a total of 7,020 birds have been recorded at this site. Purple Sandpiper has been seen in numbers as high as 180 birds, which is almost 2% of the North American population.
Tree-nesting colonial waterbirds such as herons and cormorants formerly nested here, but no longer do so as the trees can no longer support nests. In 1966, 130 Black-crowned Night-Heron nests were observed. In just one year, however, the colony was reduced to 80 nests, and by 1986 there were no breeding night-herons. In 1967, 180 Great Blue Heron nests were recorded, but in 1999 none were present. Between 700 to 1,640 Double-crested Cormorant nests were reported between the years 1965 and 1979, but in the 1980s and 1990s the number decreased steadily. No cormorants bred on the island in 1999.
Five surveys of gulls between 1965 and 1990 revealed an average of 695 pairs of Herring Gull and 53 pairs of Great Black-backed Gulls.
BirdLife International (2020) Important Bird Areas factsheet: Île Blanche. Downloaded from http://www.birdlife.org on 28/11/2020.