Lower Great Lakes-St Lawrence

Male Rose-breasted Grosbeak (photo: May Haga)
The Lower Great Lakes / St. Lawrence region encompasses Lakes Huron, Erie and Ontario, extending up the St. Lawrence Valley to cover the north and south shores of the St. Lawrence River to the river's mouth. This region is dominated by agricultural and urban landscapes, where pastures and fields provide habitat for grassland birds. Except along the northern edge of the region, forest cover is highly fragmented by the surrounding urban and agricultural lands, but forest cover has been increasing due to reforestation and regeneration of trees on marginal farmlands. This region includes the only tracts of Carolinian forest in Canada, which support a distinctive community of animals and plants.

Bird's-Eye View

  • Overall, characteristic species in this highly developed region have increased, including forest birds, water birds and waterfowl, demonstrating that people and birds can live together.
  • Substantial reductions in environmental pollution are reflected in increases in populations of colonial waterbirds and many raptors.
  • Nevertheless, some species have declined dramatically, including aerial insectivores and grassland birds. The use of bird-friendly agricultural practices could maintain agricultural production while helping to conserve or restore grassland bird populations.
  • Urban areas continue to expand in the region. Development needs to be planned carefully to retain key bird habitats and to minimize habitat loss.


In recent decades, most bird groups in the Lower Great Lakes–St. Lawrence region have increased. On average, all species are up by 20%.
Line graph depicting the percent change in population size of various bird guilds in the Lower Great Lakes since 1970 Bar chart showing the number of species in each guild with increasing or decreasing population size
Indicators of the average population status of characteristic species (click on graphic for a larger version and associated data tables)

Waterfowl have benefitted from plentiful food in agricultural areas used during the winter and improved nesting success in urban areas. Canada Goose populations have exploded, and populations of Mallard, Hooded Merganser and Wood Duck have increased by more than 50%. There has been some recovery, conservation and restoration of wetlands in the region, particularly along the St. Lawrence Seaway, that has slowed the rate of habitat loss for many waterfowl and other water birds.

Photograph of a Pileated Woodpecker on a tree trunk
Pileated Woodpecker populations have
increased and expanded into new areas as
forests mature (photo: Alan Burger)
Aerial insectivores, primarily swallows, have declined here and across the country. The causes of these declines are unknown but may include local factors, such as reduced insect populations or loss of nesting habitat, or factors on their wintering grounds. In this region, Chimney Swift, Purple Martin and Bank Swallow populations have all declined by approximately 95% since 1970.

Grassland birds have declined by 70%, with several species at risk of extirpation (local extinction). Changing agricultural practices are making farmlands less suitable as habitat, and forests have re-grown on abandoned agricultural grasslands. Although historically much of this area was forested, in the intervening centuries, the region has become an important refuge for grassland birds in Canada.

The shoreline and islands of the Canadian Great Lakes are home to eight characteristic species of gulls, terns, herons, cormorants and pelicans—waterbirds that breed in colonies. Most colonial waterbirds have increased substantially, due in part to reduced concentrations of DDT, PCBs and other pollutants, although new contaminants, changes in fish populations and disease remain as potential concerns.

Many forest birds, such as Pine Warbler, Black-capped Chickadee and woodpeckers, have increased as forests in the region have expanded and matured. However, some species are still declining.


Intensive agricultural practices—wetland draining, increased insecticide and herbicide use, removing hedgerows and field margins, and cutting of hay before chicks leave the nest—affect grassland birds like the Bobolink by reducing habitat and food and even killing birds outright.

Urban expansion—especially along shorelines, in and around forests and wetlands, and on agricultural land—is reducing, fragmenting and degrading bird habitats. In addition, expanding urban areas bring with them outdoor cats, which kill millions of birds every year.

Photograph of a Least Bittern balancing on reeds
The Least Bittern and other water birds rely
on healthy wetland ecosystems, which are
threatened by invasive species, contaminants,
shoreline development and wetland drainage.
(Photo: Gord Belyea)
Invasive species, such as purple loosestrife, Phragmites, zebra mussels, round gobies and common carp, continue to alter aquatic habitats and associated food webs, with cascading effects on food sources for colonial waterbirds, waterfowl and other water birds.

This economically significant region contains many industrial chemical sources.


Photograph of a Bobolink on a barbed-wire fence
Bobolinks populations, which have decreased by
80%, can thrive in agricultural areas, provided that
bird-friendly agricultural practices are followed.
(Photo: May Haga)
Practices have been developed for hay and forage production that can benefit grassland birds. Delay of haying until after young birds fledge, well managed grazing, maintenance of hedgerows and other bird-friendly practices should be encouraged.

Urban expansion, housing and industrial developments, and new transportation corridors should respect existing limits to development, and be planned to conserve as much of the natural landscape as possible and avoid key areas for birds, especially around shorelines and wetlands.

Photograph of a Common Nighthawk in flight
Common Nighthawks have declined dramatic-
ally, like and most other aerial insectivores,
but the causes of the decline are not well
understood. (Photo:Nick Saunders)
Increasing existing forest cover, expanding and linking larger forest patches, and ensuring sound forest management practices will all help the forest birds that are most sensitive to nearby development.

Canadians can help reduce the spread of invasive species by carefully cleaning boats and motors and not moving live fish between water bodies or firewood from region to region.

Photograph of a biologist in a colony of Ring-billed Gulls in front of the Toronto city skyline
Ring-billed gulls can thrive in close proximity to humans,
but are susceptible to pollution. Gulls in the Great Lakes
are regularly tested for contaminants as an indicator of
environmental health. (photo: Ian Parsons)

Regulations have successfully reduced concentrations of toxic chemicals such as DDT and PCBs in the eggs and blood of Great Lakes birds, but new controls are needed for emerging chemicals, including those used in flame-retardants.