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Southwestern Manitoba Mixed-Grass Prairie (MB024)

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Southwestern Manitoba Mixed-Grass Prairie (MB024)

Melita, Manitoba

Latitude 49,213°N
Longitude 101,153°O
Altitude 425 - 463m
Superficie 1 580,34km²

Description du site

The extreme southwestern corner of Manitoba, containing the towns of Melita, Lyleton and Pierson, is the driest part of the province and is dominated by sandy soils, extensive rangeland and occasional tracts of mixed-grass prairie. Much of the area is or has been cultivated at one time or another. Along the Souris River and its tributaries are coulees of scrub and deciduous riparian woodlands. Near Lyleton, hundreds of miles of shelterbelts were established to prevent wind erosion during the 1930s. Four small Wildlife Management Areas (WMAs) occur in the area. The Broomhill WMA is dominated by grassland and shrublands. Near Melita, a wide variety of introduced and planted trees and shrubs have established at the Gerald Malaher WMA. There are two widely spaced units of Pierson WMA: the Gainsborough Creek unit south of Melita contains native uplands, riparian forests and shrubland, while the Frank W. Boyd unit near Pierson is dominated by native aspen parklands woods and willow shrubbery. The recently-established Mixed-grass Prairie Preserve, southwest of Broomhill, illustrates the relationship between grazing mammals and native prairie.

Oiseaux

The Southwestern Manitoba Mixed-Grass Prairie area is rich in grassland and parkland birds, and is especially notable for rare prairie birds that are at the northern edge of their range. Four of these species are on the list of national endangered species list. The rarest of these is the nationally endangered Burrowing Owl, which still occurs in the extreme southwest in very small numbers, but is in danger of being extirpated in Manitoba. In the 1980s, 30 pairs were present, while only 3 pairs were detected in 1999. This area also holds most of Manitobas nesting Ferruginous Hawks, a globally near-threatened and nationally vulnerable species. Although less than 40 pairs currently occur in Manitoba, over 50 pairs nested in southwest Manitoba throughout most of the 1990s. This represents 1 or 2% of the Canadian population of Ferruginous Hawks. The threatened western subspecies (excubitorides) of the Loggerhead Shrike also occurs in significant numbers in extreme southwestern Manitoba. Over 100 pairs (at least 4% of the Canadian population of this subspecies) of Loggerhead Shrike have nested in this region throughout the 1990s, with a peak of 327 pairs in 1993. More than two-thirds of Manitobas current nesting populations of the Ferruginous Hawk and the western Loggerhead Shrike are found within the IBA boundaries. This area also supports most of Manitobas nesting population of Bairds Sparrow (globally near-threatened) and Spragues Pipit (globally vulnerable, nationally threatened).

Grassland areas within the IBA are rapidly becoming a popular ecotourist attraction. Each year, hundreds of bird-watchers from throughout North America visit this area to find widely sought after grassland birds. In addition to the above-mentioned species, specialties of the area that occur in the IBA in reasonable numbers include Sharp-tailed Grouse, Gray Partridge, Marbled Godwit, Upland Sandpiper, Says Phoebe, Grasshopper Sparrow, Lark Bunting and Chestnut-collared Longspur.

Enjeux de conservation

Several conservation issues are worthy of note in this unprotected private-lands IBA. Overgrazing and increased cultivation of grasslands for agriculture are situations that can lead to an elimination of native prairie, and are both of concern in the area. On the other hand, shelterbelts planted to minimize soil erosion are of importance to a wide variety of birds, including shrikes. Some of these shelterbelts are dying back and are now being destroyed.

A large bed of gravel underlies the surface of much of this site, particularly in areas favoured by breeding shrikes, Ferruginous Hawks, Bairds Sparrows and Spragues Pipits. For the time being there is no gravel extraction in this area, perhaps because this area is far from major centres, but under a different situation, gravel extraction could greatly diminish the quality of bird habitat.

The Manitoba Conservation Wildlife Branch, in conjunction with World Wildlife Fund and various local conservation groups, has studied the bird life here since the early 1980s and in particular has spent time monitoring and managing grassland species at risk.

Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
Pipit de Sprague
Nombre Année Saison
58 - 702016Été
40 - 412015Été
??Été
Quiscale rouilleux
Nombre Année Saison
652015Automne
242007Printemps
242007Hiver
Plectrophane à ventre noir
Nombre Année Saison
180 - 1972016Été
98 - 2502015Été
Pie-grièche migratrice
Nombre Année Saison
1 - 32017Été
1 - 42016Été
12016Printemps
1 - 22015Été
12015Printemps
12014Été
12013Automne
1 - 22013Été
12013Printemps
42012Automne
1 - 52012Été
1 - 22011Été
22011Printemps
1 - 62010Été
12010Printemps
1 - 62009Été
52008Automne
1 - 22008Été
22007Été
1 - 72006Été
1 - 52005Été
12005Printemps
1 - 72004Été
1 - 32003Été
62003Printemps
1 - 62002Été
1 - 32001Été
1 - 82000Été
1 - 2001999Été
1 - 41998Été
1 - 31997Été
1 - 71996Été
121996Printemps
5 - 101995Été
1 - 21994Été
1 - 6541993Été
1 - 21992Automne
1 - 61992Été
11991Été
71990Été
Chevêche des terriers
Nombre Année Saison
61999Été
41991Été
601985Été
Buse rouilleuse
Nombre Année Saison
761999Été
1121995Été