Sleeper Islands

Country/territory: Canada

IBA criteria met: -
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Area: 226 ha

Birds Canada / Nature Canada

Site description (2001 baseline)
The Sleeper Islands archipelago is located in eastern Hudson Bay about 115 km north-northeast of the community of Sanikiluaq. It stretches in a north-south direction for about 49 km, and consists of over 360 islands with all except two being smaller than 50 ha. The two larger islands are greater than 1,000 ha in size.

Most of the islands are characterized by smooth bedrock with vegetation being restricted to sheltered depressions and the larger islands. Numerous marine mammals forage over the shallow marine shelves around the islands (e.g., Ring Seal, Bearded Seal, Beluga), and during the fall the area is of especial importance to Walrus. Large, healthy populations of river run Arctic Char are also found in and around the Sleeper Islands.

Key biodiversity
The Hudson Bay population of Common Eiders (ssp. sedentaria) is non-migratory, and winters within polynyas, such as those around the Belcher Islands, and along shore leads, such as the land-fast ice edge to the north of the Belcher Islands. During a study completed in 1985, the more isolated and exposed islands around the perimeter or the archipelago were the preferred nesting sites; the archipelago likely provides one of the best eider nesting habitats in Hudson Bay.

During the 1985 survey, 2,204 Common Eider nests were recorded on 108 islands within the archipelago. This was extrapolated to provide an overall estimate of 5,900 pairs for the entire Sleeper Island Archipelago. A survey completed in 1997, however, revealed a 78.7% decline, with only 468 nests being recorded on the same 108 islands. Extrapolation in the same manner as for the earlier surveys provides an overall estimate of 1,253 pairs (or about 14% of the estimated breeding population).

Populations of gulls (Herring and Glaucous) and Arctic Terns have declined as well: gull nesting density by 25%, and tern nesting density by 53.5%. During the mid 1980s, populations of these species included 180 pairs of Glaucous Gulls, 180 pairs of Herring Gulls, and 220 pairs of Arctic Terns

Other ornithological records of note include the recent nesting of Tundra Swans on Kidney Island, and the abundance of nesting Purple Sandpipers.

Recommended citation
BirdLife International (2023) Important Bird Area factsheet: Sleeper Islands. Downloaded from on 04/10/2023.