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Location Canada, Ontario
Central coordinates 79o 4.19' West  43o 7.26' North
IBA criteria A4i, A4iii
Area 2,800 ha
Altitude 74 - 177m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description The Niagara River flows 60 km from Lake Erie to Lake Ontario. In addition to being a major tourist destination, it provides drinking water, recreational fishing, employment, and electrical power to millions of people. The river is bordered by urban areas, industrial developments, and agricultural lands with parkland areas and remnant natural areas being interspersed. For a 15 km stretch downstream from the falls the river flows through a 100 m deep and 1 km wide gorge. The riverine habitats are quite varied, ranging from large lake-like areas, exposed boulder beds, rapids, falls, whirlpools, and stretches with swift currents. Within the gorge, the cliff rim, cliff face, and talus slope communities support one of the highest concentrations of rare plant species in Ontario.

Key Biodiversity The Niagara River annually supports one of the largest and most diverse concentrations of gulls in the world. More than 100,000 individuals can be observed foraging along the river during fall and early winter. A total of 19 gull species have been recorded (60% of all New World gull species), with up to 14 species being recorded on a single day. The number of gulls and diversity of species generally peak in November. Two species occur in globally significant numbers: Bonaparte's Gull and Herring Gull.

During fall and early winter 10,000 or more Bonaparte's Gulls can regularly be observed along the river (over 2% of global population). Peaks of more than 40,000 individuals have been observed on several occasions (1973, 1977, 1990, 1991) representing over 8% of the global population. Over the course of the fall and early winter season up to 100,000 birds have been estimated to pass through this site (over 20% of the global population).

Herring Gulls are also abundant; 20,000 or more individuals can be observed regularly with a maximum of 50,000 individuals being reported on a single day. This represents the regular occurrence of almost 6% of the North American Herring Gull population (ssp. smithsonianus) with upwards of 14% of the population being reported on a single day. The national threshold for Ring-billed Gulls is also regularly exceeded during spring migration.

Waterfowl concentrations during fall and winter also regularly exceed 20,000 individuals of more than 20 species. At least two species (Canvasbacks and Common Mergansers) are regularly present during late fall and early winter in numbers just above 1% of their estimated North American populations; Greater Scaup are occasionally present in significant numbers, and Common Goldeneyes are regularly present in numbers approaching the 1% threshold.

Due to the regional geography, large numbers of migrating raptors and landbirds cross the river during migration. Normally they do not stop in large numbers along the river corridor. Some specific sites along the river corridor are also significant for colonial nesters such as Black-crowned Night Herons, Common Terns, and Ring-billed Gulls.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Canvasback Aythya valisineria winter  1997  14,000 individuals  A4i  Least Concern 
Greater Scaup Aythya marila winter  1997  10,000 individuals  A4i  Least Concern 
Larus argentatus winter  1995  20,000 individuals  A4i  Not Recognised 
Ring-billed Gull Larus delawarensis breeding  1998  16,000 breeding pairs  A4i  Least Concern 
Bonaparte's Gull Larus philadelphia passage  1995  100,000 individuals  A4i  Least Concern 
A4iii Species group - waterbirds passage  50,000-99,999 individuals  unknown  A4iii   


IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Rivers  -
Coastline Cliffs, rocky shores, islets, freshwater  -

Land use

Land-use Extent (% of site)
tourism/recreation major
urban/industrial/transport major

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Niagara River Corridor. Downloaded from on 24/10/2016

To provide new information to update this factsheet or to correct any errors, please email BirdLife