IBA Corossol Island
Sept-Îles, Québec
Site Summary
QC081 Latitude
50.090° N
66.386° W
0 - 59 m
17.12 km²
Intertidal mud, sand & salt flats, Salt & brackish marshes, Sand dunes & beaches, Boreal mixed forest, Northern temperate grassland, Scrub, Cliffs, rocky shores & islets (freshwater), Bogs, Freshwater lakes & pools, Rivers, Streams
Land Use:
Nature conservation and research, Fisheries/aquaculture, Hunting, Not Utilized (Natural Area), Tourism/recreation, Urban/industrial/transport
Potential or ongoing Threats:
Housing and urban areas, Commercial and industrial development, Mining and quarrying, Shipping lanes, Direct mortality of trigger species - hunting and trapping, Habitat effects - fishing and harvesting aquatic resources, Dams and water management/use, Industrial and military effluents, Agricultural and forestry effluents and practices, Wood and pulp plantations (includes afforestation) - agro-industry plantations
IBA Criteria: Globally Significant: Congregatory Species, Continentally Significant: Congregatory Species, Nationally Significant: Colonial Waterbird/Seabird Concentrations
Conservation status: Aire de Concentration d'Oiseaux Aquatiques - Quebec (Aquatic Birds Concentration Area), Migratory Bird Sanctuary (federal), Zone d'Intervention Prioritaire - Quebec (Priority Intervention Zone)
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Site Description
Île du Corossol is located 10 km off the north shore of the Gulf of St. Lawrence, in the bay of Sept-Iles, Québec. Corossol Island is one of several islands in the Sept-Iles Archipelago. The IBA site includes the islets, rocks and water within a 500 metre limit around the island, except in the vicinity of Manowin Island where the limit is midway between the two islands. The island is overall rocky and steep, with three intermittent streams and, being part of the Canadian shield, is underlain by granitic-gneiss bedrock. The vegetation consists mainly of white birch/white spruce mixed forests, which occupy low-lying areas and cover up to 80% of the land area. The remaining habitats consist of shrubs and peat bog. Scrub birch, Serviceberry and Balsam Fir were once harvested in the boggy depressions of the island. There is a lighthouse and a lighthouse keeper's residence and several other small buildings on the island.
An impressive number of colonial waterbirds use Île du Corossol in the breeding season. Three of these waterbirds, all larids, breed on the island in significant numbers. An average of 3,611 pairs of Herring Gull bred here between 1985 and 1998; the maximum colony size was 7,254 pairs in 1985. The average corresponds to about 3% of the North American Herring Gull population. About 1% of the North American population of Great Black-backed Gulls nests here. An average of 464 pairs nest here (1985-1998 average). The colony of Black-legged Kittiwakes is continentally significant. The three-survey average for this species is 2892 pairs - over 4,000 pairs were present in 1985 and 1988. The average represents about 1% of the Atlantic population.

The Double-crested Cormorant nests in close to continentally significant numbers, with just under 1% (or about 900 nests) of the Atlantic population nesting here.

Other breeding seabirds on Île du Corossol are: Black Guillemot (223 birds), Common Eider (581 pairs), Razorbill (815 birds), Common Murre (316 birds), and Leach's Storm-Petrel (718 birds). Data is from the most recent survey in 1998. The Atlantic Puffin and Great Blue Heron appeared here recently, with puffins first noted during the 1996 surveys, and herons in 1998. The total number of all nesting seabirds was approximately 12,700 individuals in 1993, with a density of approximately 112 pairs per ha, and about 10,500 birds in 1998.

IBA Criteria
SpeciesT | A | I Links Date Season Number G C N
Herring Gull 1982 - 1993 SU 3,000 - 14,508
Razorbill 1998 - 2010 SP 815 - 2,799
Razorbill 1993 - 2009 SU 589 - 1,000
Note: species shown in bold indicate that the maximum number exceeds at least one of the IBA thresholds (sub-regional, regional or global). The site may still not qualify for that level of IBA if the maximum number reflects an exceptional or historical occurrence.
Conservation Issues
Maritime traffic associated with the Sept-Iles harbour increases the likelihood of an oil spill. Increases in the number of tourists to the area could lead to the excessive disturbance of nesting waterbirds.

The site has been designated a Migratory Bird Sanctuary which has strict regulations that include not allowing anyone to disturb, destroy or take the nests of migratory birds. The site is also within a Priority Intervention Zone and the Archipel des Sept-Iles regional park.

The coastal area harbor a flora similar to that found along the shores of the estuary: sea pea, Scotch lovage, American searocket, sea milkwort, etc. However, there are two plants that played a key role in the dynamics of the coastal ecosystems: the American beachgrass and dune grass. These species are known to be important for “fixing sand dunes". These species are able to colonize sandy areas, where most other plants can't. Well adapted to arid conditions and equipped with a large root system, they were able to hold the soil, which then help to mitigate the erosion. In the barachois, the absence of marine currents and the shallowness of the waters favor the development of Marine eelgrass beds.

Coastal erosion is the main threat to the flora in these regions. Habitat destruction by humans (filling, draining of wetlands and shoreline riprap) is also a challenge. Risks of oil spill remain an issue of concern in theses areas.

Major species present :
American beachgrass
American searocket
Dune grass
Sea pea / Beach pea
Sea milkwort
Scotch lovage
Marine eelgrass

The IBA Program is an international conservation initiative coordinated by BirdLife International. The Canadian co-partners for the IBA Program are Birds Canada and Nature Canada.
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