IBA Wildwood Gull Roost
St. Marys, Ontario
Site Summary
ON045 Latitude
43.253° N
81.038° W
328 - 343 m
11.38 km²
freshwater lake, arable & cultivated lands
Land Use:
Agriculture, Nature conservation and research, Hunting, Rangeland/pastureland, Tourism/recreation
Potential or ongoing Threats:
IBA Criteria: Globally Significant: Congregatory Species, Colonial Waterbirds/Seabird Concentrations, Continentally Significant: Waterfowl Concentrations
Conservation status: Conservation Area (provincial)
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Site Description
Wildwood Conservation Area is located southwest of Stratford and east of the town of St. Marys, Ontario. The Conservation Area extends across the broad valley of Trout Creek. The valley slopes are covered in White Pine and White Spruce plantations, or have been left to regenerate naturally. There is little natural forest, as most of the unplanted slopes are undergoing succession from old field and hawthorn pasture stages.

Wildwood Reservoir is an impoundment of Trout Creek, a tributary from the north branch of the Thames River. The reservoir is a 9.2 km long, S-shaped lake with a summer surface area of approximately 385 ha. At the east end of the reservoir is an impoundment created by Ducks Unlimited. Beginning in late August the reservoir is drawn down to create space for fall rains and winter snow melt.

Large numbers of Ring-billed Gulls begin roosting on Wildwood Reservoir in late summer. In 1993, as many as 100,000 birds were observed on the lake at the end of August, while 110,000 were reported in October 1994. This latter figure represents about 6% of the estimated global population for this species. In November, Herring Gulls begin arriving at the site, and by December the Ring-billed Gulls have moved on. The Herring Gulls generally remain until freeze-up, although they sometimes can be found throughout the winter. In November 1998, 38,000 birds were recorded on the lake, representing 15% of the estimated North American Herring Gull population. These gulls are often accompanied during the winter months by Great Black-backed Gulls (maximum 100+), Glaucous Gulls (maximum 5-10), Iceland Gulls (max 5-10), and Lesser Black-backed Gulls (maximum 1-3). It is speculated that these gulls may be from Lake Huron and remain all winter, depending on the extent of ice on Lake Huron. When Wildwood Lake is frozen they may roost on Lake Huron, but will continue to come inland to feed and congregate on the ice on Wildwood Lake during the day.

American Black Ducks and Mallards can also be found during fall migration in large numbers. Approximately 5% of the estimated Mississippi Flyway population of American Black Ducks has been recorded here, and up to 15,000 Mallards have been observed. In addition, as many as 2,000 shorebirds are attracted to the extensive mudflats created when the reservoir is drawn down early in the fall.

IBA Criteria
SpeciesT | A | I Links Date Season Number G C N
Acadian Flycatcher 1993 FA 1
American Black Duck 1988 - 1991 FA 5,000 - 8,000
American Black Duck 1990 WI 7,500
Herring Gull 1992 - 1998 FA 5,000 - 38,000
Herring Gull 1994 - 1997 SP 3,000 - 8,500
Herring Gull 1997 SU 9,000
Herring Gull 1988 - 2002 WI 3,000 - 82,000
Little Gull 2020 SP 5
Loggerhead Shrike 1996 - 1997 SP 1
Ring-billed Gull 1991 - 1994 FA 50,000 - 110,000
Ring-billed Gull 1997 SU 40,000
Note: species shown in bold indicate that the maximum number exceeds at least one of the IBA thresholds (sub-regional, regional or global). The site may still not qualify for that level of IBA if the maximum number reflects an exceptional or historical occurrence.
Conservation Issues
Wildwood Gull Roost is a conservation area owned by the Upper Thames River Conservation Authority, and is protected under this management. There are no known threats to this site. Wildwoods swimming beaches are often closed in late summer due to bacterial contamination. However, the Conservation Authority has not taken action against the gulls.

The IBA Program is an international conservation initiative coordinated by BirdLife International. The Canadian co-partners for the IBA Program are Birds Canada and Nature Canada.
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