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Location Canada, Manitoba
Central coordinates 100o 45.02' West  49o 37.26' North
IBA criteria A4i, A4iii
Area 66,000 ha
Altitude 411 - 430m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description Oak Lake, and the associated Plum Lake, are located in southwestern Manitoba, southwest of the town that shares its name. The lake is surrounded by a vast marshland about four times its size that is fed by Pipestone Creek and drained by Plum Creek. This extensive lake and marsh system and the surrounding area, generally in very flat terrain, contain a tremendous diversity of habitat. There is a blend of rivers and streams, grasslands, deciduous woods, willow scrub, and rocky areas, along with cultivated agricultural lands. Grasses and sedges border the wetland, and remnants of undisturbed native prairie can be found. Extensive dykes surround Oak Lake, which is artificially regulated by a water control dam. Close to the town of Oak Lake there are extensive sand dunes that are heavily treed with Bur Oak, Trembling Aspen, Creeping Juniper. Located slightly further north is the Assiniboine Valley, which has a valley wall exceeding 100 m in height.

Key Biodiversity In keeping with its vast habitat diversity, this site hosts a large diversity of birds, during both the breeding season and fall migration. A large colony of Franklins Gulls nest in the marsh. Over 30,000 pairs of birds, roughly equivalent to 8.6% of the estimated global population, have been recorded. Both Eared Grebes and Black-crowned Night Herons are found here in nationally significant numbers; 4.3% and 6.3% of their estimated Canadian populations respectively.

Huge numbers of waterfowl stop at Oak and Plum Lakes in fall migration. Species reported in significant numbers during fall migration include: Tundra Swan (1.3% of the estimated North American population); Canada Goose (2.8% of the estimated Short-grass Prairie population); Snow Goose (between 1 and 3% of the estimated Mid-continent population); and Greater White-fronted Geese. For the latter species, numbers of migrants varies considerably from year to year - over 3,400 were recorded recently, but 27,000 were recorded in 1968. Similarly, significant peak numbers of Mallards, Lesser Scaup, and American Coots have been recorded in some years. Other species that can be seen in large numbers in the fall include, Bald Eagles (135+), Golden Eagles (30+), and Sandhill Cranes (3,300+).

During the breeding season landbird diversity is high. Some of the provinces highest concentrations of Eastern Bluebirds and Mountain Bluebirds are found here - 35 pairs and over 250 pairs respectively. In 1998, 11 pairs of the nationally threatened Loggerhead Shrike (western subspecies) were found here. Under optimal conditions during the breeding season, birders can daily record Nelsons Sharp-tailed Sparrow, Le Contes Sparrow, Grasshopper Sparrow, and Bairds Sparrow along the west side of the lake. Burrowing Owl and Ferruginous Hawk are two raptors known to breed in the region.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Greater White-fronted Goose Anser albifrons passage  1968  27,000 individuals  A4i  Least Concern 
Tundra Swan Cygnus columbianus passage  1995  2,800 individuals  A4i  Least Concern 
Franklin's Gull Larus pipixcan breeding  1995  30,000 breeding pairs  A4i  Least Concern 
A4iii Species group - waterbirds breeding  1995  20,000-49,999 breeding pairs  unknown  A4iii   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Upper Assiniboine Wildlife Management Area 999 protected area overlaps with site 490  


IUCN habitat Habitat detail Extent (% of site)
Forest Temperate deciduous woods  -
Shrubland Scrub  -
Grassland Edaphic grassland  -
Wetlands (inland) Freshwater lakes and pools; Freshwater marshes/swamps; Rivers  -
Artificial - terrestrial Arable land  -

Land use

Land-use Extent (% of site)
agriculture major
nature conservation and research major
fisheries/aquaculture minor
hunting minor
rangeland/pastureland major
tourism/recreation major
water management major

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Oak Lake/Plum Lakes Area. Downloaded from on 27/10/2016

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