Dundas Valley and Dundas Marsh

Country/territory: Canada

IBA Criteria met: -
For more information about IBA criteria please click here

Area: 20 ha

Birds Canada / Nature Canada

Site description
The Dundas Valley is an extensive natural area located in southern Ontario along the Niagara Escarpment. Immediately to the east is the town of Dundas and Dundas Marsh (also called Cootes Paradise). The Spring Creek valley forms a narrow, natural corridor joining Dundas Valley to Dundas Marsh. Most of the Dundas Valley area is comprised of relatively undisturbed deciduous and mixed upland forest. The topography is quite varied, being comprised of rolling hills, deeply incised stream courses, and steep valley walls, with local relief of 30 metres or more being common. Dundas Marsh is located at the western end of Hamilton Harbour, and is a shallow flooded basin of open water and marsh joined to Hamilton Harbour by the Desjardins Canal. The shallow open water pond is dominated by water lilies and Sago Pondweed while the shoreline is dominated by cattail and Manna Grass. The surrounding terrain consists of rolling hills and ravines, covered woods and successional communities.

Also included in the site are Spencer Creek Gorge and Tiffany Falls. The flora and fauna of the valley and marsh have been well studied with an exceptional concentration of significant flora and fauna being present. Over 580 species of vascular plants have been recorded for the valley (17 nationally and/or provincially rare), and over 800 species for the marsh (25 of which are nationally rare).

Key biodiversity
The Dundas Valley contains a nationally significant community of forest birds. Breeding evidence for at least five nationally vulnerable, threatened or endangered species has been recorded. Two of these threatened species are regularly present in nationally significant numbers (i.e., greater than 1% of their national population). These species are the Hooded Warbler (two to four pairs annually), and Louisiana Waterthrush (two to four pairs annually). Cerulean Warbler (nationally vulnerable) is also present within the valley, but not in nationally significant numbers. Yellow-breasted Chat (nationally vulnerable) and Acadian Flycatcher (nationally endangered) have also been recorded within the valley, but only on an irregular basis.

During recent years, about 100 species of breeding birds have been recorded within the valley (one of the more species rich areas in southern Ontario). A relatively large proportion of these are neotropical migrants, of which the more abundant species are Red-eyed Vireo, Wood Thrush, Eastern Wood-Peewee, Ovenbird, and Scarlet Tanager. Of additional ornithological interest is the presence of both hybrids of Blue-winged and Golden-winged Warblers.

Dundas Marsh is an important area for migrating waterfowl, shorebirds, herons, raptors, gulls, terns, and songbirds. There is confirmed breeding evidence for three species at risk in Canada: Least Bittern (vulnerable), Cerulean Warbler (vulnerable) and Prothonotary Warbler (endangered), the latter having nested annually for the last five or so years, and has nested here regularly, but not annually, since at least the 1950s. In addition, Yellow-breasted Chat (vulnerable) possibly bred in 1974, as might a pair of King Rails (endangered) in the 1960s. Other breeding species include Double-crested Cormorant (121 nests in 1997), Blue-winged Teal, Common Moorhen, Yellow-billed Cuckoo, Whip-poor-will, Eastern Bluebird, Tufted Titmouse, Carolina Wren, Black-throated Green Warbler and Orchard Oriole.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Dundas Valley and Dundas Marsh. Downloaded from on 03/12/2022.