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Hamilton Harbour Waterbird Colonies (ON020)


Hamilton Harbour Waterbird Colonies (ON020)

Hamilton, Ontario

Latitude 43.287°N
Longitude 79.804°W
Altitude 75 - 78m
Area 14.23km²

Site Description

Hamilton Harbour is located at the extreme western end of Lake Ontario. It is separated from the Lake by a large sandbar (developed with highways, industries, and housing), with water exchange occurring through the Burlington Canal. The waterbird colonies are located at east end of the harbour, primarily in an area known as Eastport, as well as in the harbour's northeast corner.

Eastport is comprised of three partially developed piers (numbers 25, 26, and 27) that have been created over the past 35 years by the Hamilton Harbour Commission's filling operations. Eastern Cottonwood has become established on some of the piers, although in recent years it has died back (probably due to the acidic feces from nesting Double-crested Cormorants). In general, the piers at Eastport are flat with some elevated mounds (less than 2 m), and herbaceous vegetation such as celandines, mustards, and nettles.

Two small artificial islands (Farre and Neare Islands), which are comprised of coarse rocks and patches of sparse vegetation, are located in the northeast corner of the harbour. They were built in the 1920s and supported hydro poles until they were removed in 1983. Three additional nesting islands were constructed in this area during the winter of 1995-1996. They are located directly north of the Canadian Centre for Inland Waters and are called North, Central and South islands.


In terms of the IBA program, at least four species are present at this site in significant numbers: Ring-billed Gulls (almost 4.5% of the worlds estimated breeding population); Caspian Terns (about 1.25% of the estimated North American population, and as much as 7% of the estimated Great Lakes population); Common Terns (about 1.9% of the estimated North American population), and historically Black-crowned Night- Herons. The long-term population average for Black-crowned Night Herons (1987-1997) represents about 2% of Canada's estimated breeding population; in recent years, however, numbers (20 pairs in 1997) have been well below the national 1% threshold.

Other species of waterbirds nesting at these colonies include: Double-crested Cormorants (avg. of 422 pairs from 1987-97, with a peak of 819 pairs in 1996); and Herring Gulls (avg. of 290 pairs from 1987-1997, with a peak of 371 pairs in 1996). The only Canadian record of breeding Snowy Egret occurred here in 1986.

Conservation Issues

The management and monitoring of these colonies is being undertaken by the Canadian Wildlife Service, Brock University, and McMaster University. Local stakeholders, such as naturalists clubs, are also being encouraged to participate. Management efforts have focused primarily on enhancing nesting conditions for target species such as Black-crowned Night-Herons, Common Terns and Caspian Terns. The islands recently constructed in the northeast corner of the harbour were designed specifically to attract these species. On North Island, a 200m² elevated mound was constructed of sand and pea gravel to attract Caspian Terns. Areas of sand and gravel, each 250m², were placed on both North and Centre island to attract Common Terns. Two additional areas, one on Centre Island and all of South Island, were covered with topsoil and leaf mulch in preparation for planting of native shrubs to attract Black-crowned Night-Herons.

IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status
Greater Scaup
Number Year Season
Ring-billed Gull
Number Year Season
Little Gull
Number Year Season
Long-tailed Duck
Number Year Season
Loggerhead Shrike
Number Year Season
Caspian Tern
Number Year Season