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Hardwood Transition / Lower Great Lakes – More Information

Background information on DU's Hardwood Transition / Lower Great Lakes / St. Lawrence Plain - Ontario conservation priority area
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Throughout the Mixed Woodland Plain, many of the wetlands that remain have been degraded and are of reduced value to waterfowl. However, despite extensive loss of wetlands within the region, quality wetlands and wetland complexes that support relatively high densities of breeding waterfowl still exist (Gabor et al. 1999). These are typically associated with low to moderate agricultural intensity, a result of currently unfavourable “land improvement” conditions. Since the mid 1900s beaver populations have recovered from previous over trapping thus helping to mitigate extensive wetland loss through their wetland creation activities.

The Mixed Woodland Plain is particularly valuable as breeding habitat to mallard, wood duck, blue-winged teal, green-winged teal, black duck, hooded merganser and Canada geese. Of these, mallard, wood duck and Canada geese make up a large percentage although in the recent past blue-winged teal were an important component of the breeding waterfowl population. Since mallards have expanded in the region, black ducks have correspondingly declined. Breeding mallard numbers began to rise in Ontario after 1950 and have grown to be the most common breeding duck in the region. CWS data shows the most abrupt increase in the number of mallards observed during surveys through the 1970s – 1980s. Since that time the number of mallards counted during ground surveys have leveled off in southern Ontario suggesting that mallards have saturated this landscape and are now limited by habitat (CWS Unpublished).

Human threats (i.e. urban expansion, agricultural activities) to much of the remaining waterfowl habitats of this region remain high. Fortunately southern Ontario society is beginning to see wetlands in a new light and acknowledge the value of this diminishing resource. There is tremendous opportunity to revive the expansion of waterfowl populations in the GLSL. Highly productive soils, historic wetland density and the conducive climate of this region affirm that the Mixed Woodland Plains is capable of supporting much greater densities of breeding waterfowl. The rapid increase in breeding populations of mallard, wood duck and Canada geese attest to the productivity of this region for breeding waterfowl.


  • Sustain breeding waterfowl populations to a mean of 10 breeding waterfowl pairs/km2.
  • Secure an average of 8-10 wetlands/km2 in a combination of habitats ranging from ephemeral to permanent to support the waterfowl breeding pair goal.
  • Secure a minimum of 1 permanent wetland/km2 as suitable habitat for brood rearing.
  • Secure 30-40% upland nesting cover of which 5-10% is forested to meet cavity-nesting requirements.
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