North, West, and East Shoal Lakes (MB038)
Description du site
North, West, and East Shoal lakes are located in the southern part of the Interlake region of Manitoba. The area used to consist of one lake, but in 1912 when the Wagon Creek drain was constructed, the water level fell four to five metres. The lakes are alkaline and contain a number of islands. There are some rocky areas around these lakes, and the country surrounding them is generally cattle pasture - and is extremely flat. The flat terrain means that fluctuations in water levels significantly affect the presence of different habitats. The area north of North Shoal Lake is predominantly cattail marsh and ephemeral wetlands dominate the areas between the three lakes.
The North, West and East Shoal Lakes are highly significant for enormous congregations of migrating waterfowl and high numbers of nesting pelicans, grebes and plovers. As much as 2.2% (1,935 nests) of the estimated global American White Pelican population was recorded at this site. Another significant breeder, prior to the current wet cycle leading to elevated water levels, is the globally vulnerable and nationally endangered Piping Plover. Over six years, between 1985 and 1996 an average of 46 plovers were recorded in West Shoal Lake (26 in 1996). The maximum number approximates to globally significant concentrations of this species. Piping Plover habitat has disappeared during the current wet cycle and it has been a number of years since this species was recorded here.
During the fall migration, vast flocks of Canada Geese and Snow Geese are observed. Peak one day counts have recorded as many as 100,000 Cackling Geese and about 200,000 Snow Geese. Other waterfowl numbers recorded include over 50,000 ducks of mixed species that were observed on several single day counts.
Other birds that have been known to breed at this site in small numbers include: Western Grebe (400 nests in 1979), Ring-billed Gull (450 nests in 1986), Herring Gull (232 nests in 1979), Black-crowned Night-Heron (6 nests), Eared Grebe (500 nests), Common Tern (40 nests in 1986), Double-crested Cormorants (263 nests in 1986), Least Bittern, Willet and American Avocet. There is also a probable breeding colony of Franklin’s Gulls here - 1,642 were counted in July 2017. The threatened Red-headed Woodpecker breeds in woodlots surrounding the lakes.
Enjeux de conservation
The breeding populations of colonial nesting species, and to a lesser degree, waterfowl here, are very affected by fluctuating water levels due to dryer or wetter years. Since the turn of the century, Manitoba has been experiencing a prolonged wet cycle, with higher than average water levels being experienced in many areas. In the North, West and East Shoal Lakes, this has led to large areas of terrestrial land being flooded and even the loss of some road access. West and East Shoal Lake have also amalgamated into a single water body. This has certainly had a negative impact on Piping Plover and pelican breeding habitat. Alkaline flats, the favoured breeding habitat for Piping Plovers have disappeared many of the low-lying islands favoured by pelican colonies have similarly disappeared underwater. The pelicans nesting colonies may also be vulnerable to site-specific disturbances such as pesticides. The IBA has in recent years been subject to land purchases by the Province of Manitoba, securing wetland habitat. These lands make up parts of the Clematis and Harperville Wildlife Management Areas. Most of the lands surrounding West Shoal Lake are part of a provincial Gamebird Refuge.
Menaces Potencielles ou Existantes
Status de Protection