IBA West End of Lake Ontario
Hamilton, Ontario
Site Summary
ON022 Latitude
43.315° N
79.520° W
75 m
549.54 km²
freshwater lake
Land Use:
Tourism/recreation, Urban/industrial/transport, Water management
Potential or ongoing Threats:
Disturbance, Industrial pollution, Recreation/tourism
IBA Criteria: Globally Significant: Congregatory Species, Waterfowl Concentrations
Conservation status:
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Site Description
This site is defined generally as the part of Lake Ontario west of a line stretching from Port Credit on the north shore to the mouth of the Niagara River on the south shore, and bounded on the west by Burlington Bar. The shoreline is one of low relief (<10m), with unconsolidated cliffs of clay-silt sediments. The coast is straight, with beaches across the mouths of small rivers ('Southeast Coast' subdivision), sedimentary rock outcrops ('Burlington Bar System' subdivision), and a wide sand barrier, up to 2 m, high across Hamilton Harbour. There is widespread artificial protection of the shoreline. Erosion rates are low as shoreline is relatively sheltered and prevailing winds are westerly. Shore-zone ice can persist up to 4 months; ice forms at west end of the lake by late December, and breaks appear in late February. Water currents are sensitive to wind direction, but appear to be predominantly counter-clockwise around Lake Ontario. Water temperatures reach 24 degrees C in late summer. Maximum lake depth at the west end of the lake is 100 m; lake contours indicate a gradual slope from the shoreline to this depth.

Beginning in 2015, an IBA-wide volunteer waterbird census is being held every other Saturday. More details, including a Map are available here.
The west end of Lake Ontario is not a discrete area, but is defined by the impressive congregations of waterfowl which have gathered there annually since about 1990, primarily in late winter and early spring. Flocks of mainly diving ducks number in thousands, sometimes tens of thousands, with the more abundant species being Greater Scaup, White-winged Scoter, and Long-tailed Ducks (these three species all occur in numbers greater than 1% of their estimated North American population). Amongst these huge flocks, several other species of diving duck occur in impressive numbers for an inland location - including Common Goldeneye, King Eider, Red-breasted Merganser, and Surf Scoter.

Where the flocks gather within this area appears to be weather dependent; that is, strong winds cause the flocks to shift locations, presumably in response to demands for shelter and feeding opportunities. The concentrations of waterfowl are most likely in response to the invasion and colonization of the shallow waters by dreissenid mussels, Zebra Mussel Dreissena polymorpha and Quagga Mussel D. bugensis. It is likely that most foraging for mussels by scaups, goldeneyes and scoters occurs on shelves less than 20 m deep around the perimeter of the lake; however, Long-tailed Ducks can forage in depths up to 100 m.

IBA Criteria
SpeciesT | A | I Links Date Season Number G C N
Acadian Flycatcher 2000 - 2014 SP 1 - 2
Barn Owl 2009 FA 1
Chimney Swift 2005 - 2015 FA 25 - 230
Chimney Swift 2010 - 2015 SP 25 - 40
Chimney Swift 2007 - 2012 SU 24 - 25
Common Goldeneye 1994 - 2003 WI 8,700 - 30,000
Greater Scaup 1993 - 2004 FA 4,500 - 25,000
Greater Scaup 1993 - 1995 SP 6,750 - 10,000
Greater Scaup 1992 - 2015 WI 5,000 - 100,000
Kirtland's Warbler 2012 SP 1
Little Gull 2002 - 2015 FA 2 - 3
Little Gull 2003 - 2015 SP 2 - 7
Long-tailed Duck 1994 - 2015 FA 8,000 - 200,000
Long-tailed Duck 1993 - 2002 SP 10,000 - 40,000
Long-tailed Duck 1999 - 2016 WI 8,000 - 68,920
Prothonotary Warbler 1993 - 2011 SP 1 - 2
Prothonotary Warbler 2007 SU 1
Red-breasted Merganser 1990 - 2015 FA 2,000 - 6,000
Red-breasted Merganser 2010 - 2013 WI 2,600 - 6,357
Red-necked Grebe 1998 - 2012 FA 400
Red-necked Grebe 1996 - 2012 SP 350 - 2,000
Red-throated Loon 1995 FA 327 - 490
Rusty Blackbird 2011 - 2013 FA 25 - 56
Rusty Blackbird 2007 - 2015 SP 25 - 70
Waterbirds 1995 FA 30,000
White-winged Scoter 1995 - 2014 FA 5,000 - 11,100
White-winged Scoter 1992 - 2010 SP 5,000 - 15,000
White-winged Scoter 1993 - 2014 WI 4,364 - 18,235
Yellow-breasted Chat 2012 - 2013 FA 1
Yellow-breasted Chat 1995 - 2011 SP 1
Yellow-breasted Chat 2005 SU 1
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
Pollution is the primary concern due to the amount of industrial development and agriculture around the western end of Lake Ontario. In particular, the biomagnification of toxics and pesticides through dreissenid mussels as food for the diving ducks is a concern. Shoreline development also has the potential for impacting birds, as does irresponsible disturbance of flocks by watercraft.

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