North Lake Winnipegosis Reefs (MB102)

Northern Lake Winnipegosis, Manitoba

Site Description

The North Lake Winnipegosis Reefs are located in the northern part of Lake Winnipegosis in Manitoba. Lake Winnipegosis is a large (5,403 km²), shallow (maximum depth ~55 m), freshwater lake with many small islands. Deciduous and coniferous forests border Lake Winnipegosis, with large expanses of freshwater marsh occurring along the lake.

The IBA consists of six reefs associated with a group of islands in a channel between Muddy Bay to the north and Cameron Bay to the south. The IBA is also located to the north of the Sapotaweyak Cree Nation Reserve. The six reefs are known as Dory’s Reef, Spruce Island Reef (north end), Spruce Island Reef (south end), North Long Island East Point, North Long Island (south end) and North Long Island (north end). Many of the habitats of these islands are unrecorded but it is known that North Long Island is forested with mainly elm trees.

This IBA is an amalgamation of four previous IBAs: MB66 North Channel Island IBA; MB67, Dory’s Reef IBA; MB70, South Long Island IBA and; MB98 Spruce Island Reef IBA.

Birds

These reefs support globally significant numbers of breeding colonial waterbirds, especially American White Pelican, Double-crested Cormorant and Caspian Tern.

The Spruce Island Reefs support globally significant numbers of Caspian Terns, and a large mixed colonial waterbird colony. Approximately 3,000 Caspian Terns nested on the Spruce Island Reefs in 1999. This represents over 3% of this species North American population, and may have been the largest Caspian Tern colony in Canada.

In 1999, there were 1,467 American White Pelicans nesting on Dory’s Reef, over 1% of the global breeding population of this species. Large numbers of Common Terns also nest at Dorys Reef; a 1999 survey found 641 nests.

North Long Island (north end) supported 817 American White Pelican nests and 4,540 Double-crested Cormorant nests in 1999. North Long Island (south end) also supported significant concentrations of breeding cormorants and pelicans in 1999. There were 8,032 Double-crested cormorant nests, which is over 1% of this species global population. There were also 1,925 American White Pelican nests, which is more than 1% of the estimated global population of this species.

A survey in 2012 counted a total of 2,373 American White Pelican nests between the six reefs, representing over 2% of the global breeding population of this species. There were also 8,468 Double-crested Cormorants adults, 387 Caspian Tern nests, 325 Common Tern nests, 2,728 Ring-billed Gull adults and 189 Herring Gull adults. Small numbers of California Gull, Bald Eagle, American Widgeon, Canvasback, Redhead, Common Merganser and Red-breasted Merganser have also been recorded here during breeding surveys.

Conservation Issues

Colonial waterbirds nesting in Lake Winnipegosis face several problems. Some residents whose livelihood depends on fishing feel that the birds are eating too many fish. As a result, birds are sometimes shot, or nests are destroyed.

IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status