Hamilton Harbour Waterbird Colonies

Country/territory: Canada

IBA Criteria met: A4iii (2008)
For more information about IBA criteria please click here

Area: 1,000 ha

Birds Canada / Nature Canada

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.

Key biodiversity
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.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Hamilton Harbour Waterbird Colonies. Downloaded from on 28/09/2022.