Oak Hammock Marsh is a marsh and a wildlife management area located north of Winnipeg, Manitoba, Canada. The WMA is considered to be a Class IV protected area under the IUCN protected area management categories. The marsh is recognized as an Important Bird Area (IBA) for its globally significant numbers of waterfowl and shorebirds. It is a designated

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

and

fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires. T ...

near the south-western corner of

Lake Winnipeg Lake Winnipeg (french: Lac Winnipeg, oj, ᐑᓂᐸᑲᒥᐠᓴᑯ˙ᑯᐣ, italics=no, Weenipagamiksaguygun) is a very large, relatively shallow lake in North America, in the Provinces and territories of Canada, province of Manitoba, Canada. I ...

. This larger marsh had the original English name of St. Andrews Bog. But the original wetland underwent drainage for agricultural purposes beginning in 1897, and by the early 1960s all but 60 ha had been drained. Measures to restore a portion of the wetland began in 1967 when the Governments of

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

and

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

embarked on a cooperative program with

Ducks Unlimited Canada Ducks Unlimited Canada (DUC) is a Canadian non-profit organization that works to conserve, restore and manage Canadian wetlands in order to preserve habitat for North American waterfowl, wildlife and people. They work with industry leaders, gover ...

and other wildlife conservation organizations to restore marginal agricultural lands to a state suitable for wildlife. By 1974, 3,450 ha of land had been purchased and 22 km of dykes built to trap and hold water in three dyke-separated marsh compartments. In addition, 58 nesting islands were constructed within the three compartments. In 1984, the

government signed a further development agreement with Ducks Unlimited Canada to construct water control structures, water supply works, more nesting islands, additional dykes, and create a fourth compartment.

Geography

Oak Hammock Marsh consists of approximately of open marsh, and a slightly smaller area of surrounding woods and grasslands. It is located near the town of

Stonewall, Manitoba Stonewall is a town in the Canadian province of Manitoba with a population of 5,046 as of the 2021 census. The town is situated approximately north of Winnipeg on PTH 67. It is known for its limestone quarries. The local festival is the Quarry ...

in the

Rural Municipality of Rockwood In general, a rural area or a countryside is a geographic area that is located outside towns and cities. Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry typically are describ ...

. The marsh is a re-constructed and managed wetland, designed for the creation of a waterfowl breeding and migratory habitat. Water levels in the marsh are carefully controlled. It is common during wet years (when waterfowl have an abundance of alternative nesting sites) for the water level in one or more of the compartments to be lowered for the summer, creating an extensive area of dried mudflats. This drying and later reflooding promotes the growth of emergent marsh plants such as

bulrush Bulrush is a vernacular name for several large wetland grass-like plants *Sedge family (Cyperaceae): **''Cyperus'' **''Scirpus'' **'' Blysmus'' **''Bolboschoenus'' **''Scirpoides'' **''Isolepis'' **''Schoenoplectus'' **''Trichophorum'' *Typhacea ...

and

cattail ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in A ...

, and therefore maintains the vegetation cover of the marsh; otherwise, the natural tendency would be for the marsh to become over several years simply a shallow lake, with a sharply defined shoreline and little nesting cover. Furthermore, not all of the adjacent purchased land has been allowed to grow wild. Cereal grain crops are planted in some of it, in order to supply migrating waterfowl with an autumn food supply while reducing crop losses on local farms. Bird_Migration_at_Oak_Hammock_Marsh_(48241173106)

Bird_Migration_at_Oak_Hammock_Marsh_(48241173106)

Critics contend that the marsh is simply a "duck factory" for the benefit of hunters. Supporters believe that it would be unrealistic to expect that the required funds to recreate the marsh would have been forthcoming if wild ducks had no economic and recreational value to sportsmen. Oak Hammock Marsh, like other

prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s, supports many wildlife species besides game birds. The marsh itself is closed to hunting, but game birds (primarily

mallards The mallard () or wild duck (''Anas platyrhynchos'') is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa, and has been introduced species, introduced to New Zealand, Australia, Peru, Bra ...

snow geese The snow goose (''Anser caerulescens'') is a species of goose native to North America. Both white and dark morphs exist, the latter often known as blue goose. Its name derives from the typically white plumage. The species was previously placed ...

, and

Canada geese The Canada goose (''Branta canadensis''), or Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is o ...

) are hunted in the autumn when they leave the marsh to feed in the surrounding grain fields. The waterfowl is additionally protected by a buffer zone extending 1 km from the water inside which hunting is prohibited, this protection extending outside of the WMA in some locations. The western shore of the marsh is home to

's national head office, in a building that also serves as a public Interpretive Centre for the marsh. Boardwalks from the Interpretive Centre allow public access to the marsh and dykes. The building of a head office and public facility so close to critical wildlife habitat was the cause of controversy in the 1980s.

Ecology

Spring and fall migration

More than 280 species of birds have been reported from the area, many of them during the spring and fall migrations. Numbers of staging waterfowl peak in early October when more than 300,000 ducks and geese may be present. Other species gathering in large numbers in the fall include

Yellow-headed blackbird The yellow-headed blackbird (''Xanthocephalus xanthocephalus'') is a medium-sized blackbird with a yellow head. It is the only member of the genus ''Xanthocephalus''. Description Measurements: * Length: 8.3-10.2 in (21-26 cm) * Weight: ...

Red-winged blackbird The red-winged blackbird (''Agelaius phoeniceus'') is a passerine bird of the family Icteridae found in most of North America and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and ...

, and

Bank swallow The sand martin (''Riparia riparia''), also known as the bank swallow (in the Americas), collared sand martin, or common sand martin, is a migratory passerine bird in the swallow family. It has a wide range in summer, embracing practically the w ...

. The area is an important migration support for several shorebird species—

White-rumped sandpiper The white-rumped sandpiper (''Calidris fuscicollis'') is a small shorebird that breeds in the northern tundra of Canada and Alaska. This bird can be difficult to distinguish from other similar tiny shorebirds; these are known collectively as "pee ...

Short-billed dowitcher The short-billed dowitcher (''Limnodromus griseus''), like its congener the long-billed dowitcher, is a medium-sized, stocky, long-billed shorebird in the family Scolopacidae. It is an inhabitant of North America, Central America, the Caribbea ...

Hudsonian godwit The Hudsonian godwit (''Limosa haemastica'') is a large shorebird in the sandpiper family, Scolopacidae. The genus name ''Limosa'' is from Latin and means "muddy", from ''limus'', "mud". The specific ''haemastica'' is from Ancient Greek and means ...

— as well as

Sandhill crane The sandhill crane (''Antigone canadensis'') is a species of large crane of North America and extreme northeastern Siberia. The common name of this bird refers to habitat like that at the Platte River, on the edge of Nebraska's Sandhills on t ...

American white pelican The American white pelican (''Pelecanus erythrorhynchos'') is a large aquatic soaring bird from the order Pelecaniformes. It breeds in interior North America, moving south and to the coasts, as far as Central America and South America, in winte ...

, and

Tundra swan The tundra swan (''Cygnus columbianus'') is a small swan of the Holarctic. The two taxa within it are usually regarded as conspecific, but are also sometimes split into two species: Bewick's swan (''Cygnus bewickii'') of the Palaearctic and the w ...

Snowy owl The snowy owl (''Bubo scandiacus''), also known as the polar owl, the white owl and the Arctic owl, is a large, white owl of the true owl family. Snowy owls are native to the Arctic regions of both North America and the Palearctic, breeding mos ...

Short-eared owl The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...

Bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...

, and

Northern harrier The northern harrier (''Circus hudsonius''), or ring-tailed hawk, is a bird of prey. It breeds throughout the northern parts of the northern hemisphere in Canada and the northernmost USA. The northern harrier migrates to more southerly areas ...

can be seen in the fall and into winter.

Breeding birds

More than 90 species of birds are known to have bred at Oak Hammock Marsh. Colonial nesters represented by significant numbers include

Franklin's gull Franklin's gull (''Leucophaeus pipixcan'') is a small (length 12.6–14.2 in, 32–36 cm) gull. The genus name ''Leucophaeus'' is from Ancient Greek ''leukos'', "white", and ''phaios'', "dusky". The specific ''pipixcan'' is a Nahuatl name fo ...

Black tern The black tern (''Chlidonias niger'') is a small tern generally found in or near inland water in Europe, Western Asia and North America. As its name suggests, it has predominantly dark plumage. In some lights it can appear blue in the breeding se ...

Forster's tern Forster's tern (''Sterna forsteri'') is a tern in the family Laridae. The genus name ''Sterna'' is derived from Old English "stearn", "tern", and ''forsteri'' commemorates the naturalist Johann Reinhold Forster. It breeds inland in North America ...

Black-crowned night heron The black-crowned night heron (''Nycticorax nycticorax''), or black-capped night heron, commonly shortened to just night heron in Eurasia, is a medium-sized heron found throughout a large part of the world, including parts of Europe, Asia, and N ...

, and

Herring gull Herring gull is a common name for several birds in the genus ''Larus'', all formerly treated as a single species. Three species are still combined in some taxonomies: * American herring gull (''Larus smithsonianus'') - North America * European he ...

. Upland nesters include

Blue-winged teal The blue-winged teal (''Spatula discors'') is a species of bird in the duck, goose, and swan family Anatidae. One of the smaller members of the dabbling duck group, it occurs in North America, where it breeds from southern Alaska to Nova Scotia ...

Northern shoveler The northern shoveler (; ''Spatula clypeata''), known simply in Britain as the shoveler, is a common and widespread duck. It breeds in northern areas of Europe and across the Palearctic and across most of North America, wintering in southern Euro ...

and

Northern pintail The pintail or northern pintail (''Anas acuta'') is a duck species with wide geographic distribution that breeds in the northern areas of Europe and across the Palearctic and North America. It is migratory and winters south of its breeding ra ...

. Nesting islands and wetland edges are utilized by

Mallard The mallard () or wild duck (''Anas platyrhynchos'') is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa, and has been introduced to New Zealand, Australia, Peru, Brazil, Uruguay, Arge ...

Gadwall The gadwall (''Mareca strepera'') is a common and widespread dabbling duck in the family Anatidae. Taxonomy The gadwall was first described by Carl Linnaeus in his landmark 1758 10th edition of ''Systema Naturae''. DNA studies have shown that ...

Canvasback The canvasback (''Aythya valisineria'') is a species of diving duck, the largest found in North America. Taxonomy Scottish-American naturalist Alexander Wilson described the canvasback in 1814. The genus name is derived from Greek ''aithuia'', ...

Redhead Red hair (also known as orange hair and ginger hair) is a hair color found in one to two percent of the human population, appearing with greater frequency (two to six percent) among people of Northern or Northwestern European ancestry and ...

Lesser scaup The lesser scaup (''Aythya affinis'') is a small North American diving duck that migrates south as far as Central America in winter. It is colloquially known as the little bluebill or broadbill because of its distinctive blue bill. The origin of ...

Ruddy duck The ruddy duck (''Oxyura jamaicensis'') is a duck from North America and one of the stiff-tailed ducks. The genus name is derived from Ancient Greek ''oxus'', "sharp", and ''oura'', "tail", and ''jamaicensis'' is "from Jamaica". Taxonomy The ru ...

Western grebe The western grebe (''Aechmophorus occidentalis'') is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe". Western grebe fossils from the Late Pleistocene of southwest North America we ...

and

Eared grebe The black-necked grebe or eared grebe (''Podiceps nigricollis'') is a member of the grebe family of water birds. It was described in 1831 by Christian Ludwig Brehm. There are currently three accepted subspecies, including the nominate subspeci ...

Plants

Cattails ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in A ...

bulrushes Bulrush is a vernacular name for several large wetland grass-like plants *Sedge family (Cyperaceae): **''Cyperus'' **''Scirpus'' **'' Blysmus'' **''Bolboschoenus'' **''Scirpoides'' **''Isolepis'' **''Schoenoplectus'' **''Trichophorum'' *Typhacea ...

and

common reed ''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall. Description ''Phragmites australis'' commonly forms extensive stands (known as reed beds), which may ...

are frequent in the flooded impoundments. Willow clumps grow in drier areas. Some areas that were previously under cultivation are planted with nesting cover, while lure crops are grown in others. The Brennan Prairie is found on the west side of the WMA. In the southeastern corner, a second tall grass prairie remnant abuts an area of aspen-oak forest. More than 100 species are found in the area, including

big bluestem ''Andropogon gerardi'', commonly known as big bluestem, is a species of tall grass native to much of the Great Plains and grassland regions of central and eastern North America. It is also known as tall bluestem, bluejoint, and turkeyfoot. Taxon ...

little bluestem ''Schizachyrium scoparium'', commonly known as little bluestem or beard grass, is a species of North American prairie grass native to most of the contiguous United States (except California, Nevada, and Oregon) as well as a small area north of t ...

switchgrass ''Panicum virgatum'', commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the ...

, prairie cord grass, needle and thread grass, prairie lily, golden Alexanders, and blazingstar.

References

External links

Harry J. Enns Wetland Discovery Centre

Oak Hammock Marsh on iNaturalist

Oak Hammock Marsh on eBird
{{authority control Lakes of Manitoba Marshes of Canada Ramsar sites in Canada Important Bird Areas of Manitoba Stonewall, Manitoba Nature centres in Manitoba Protected areas of Manitoba Wildlife management areas of Manitoba

History

Geography

Ecology

Spring and fall migration

Breeding birds

Plants

See Also

References

External links