Bellechasse Island

Île de Bellechasse (46°55′51.69″ N, 70°46′05.96″ W) is a small coastal island colony (~550 m in length) located in the St. Lawrence Estuary, Québec, Canada. The island lies approximately 1 km from the Québec mainland and is situated ~36 km downstream of the highly urbanized Québec City metropolitan area (human population >850,000) and ~33 km downstream of the city of Lévis (human population >150,000). Bellechasse occurs at the interface between the fluvial and estuarine portions of the St. Lawrence system, where freshwater and brackish waters converge, providing access to a diverse assemblage of fish and aquatic invertebrates. The surrounding marine environment and shorelines are highly influenced by anthropogenic activities, including industrial ports, small-scale commercial fisheries, and multiple marinas. Adjacent mainland habitats are dominated by rural land use, primarily agricultural fields, small towns, and several waste management facilities.

The island supports a mixed breeding seabird assemblage dominated by Herring Gulls (Larus argentatus), with an estimated ~604 breeding pairs. Additional breeding species include Double-crested Cormorants (Nannopterum auritum) and Ring-billed Gulls (Larus delawarensis).

Annual research projects on herring gulls have been conducted by Environment and Climate Change Canada (ECCC) since 2008 and McGIll University since 2023. Bellechasse island became a SEATRACK location in 2024 with the deployment of GPS-GSM loggers on herring gulls.