These pretty birds are making a wonderful comeback from near extinction. Lake Ontario is not their normal habitat which is the west coast of British Columbia and parts of Alaska and the interior of British Columbia and Idaho.
Every spring and summer when I venture down to Lake Ontario there they are in pairs or singles, some with cygnets paddling in tow. Large at 60 inches, their wingspan is 96 inches. For awhile there were only a few pairs; and now there are multiple groups of them along Lake Ontario wherever people venture to offer food. They'll take wild birdseed as fast as the ducks and Canada Geese do.
Photo Credits:  Grant Gingko CC=nd-sa-flickr,  steveharris CC=nc-flickr.
Research: A Field Guide to the Birds of North America by Michael Vanner, Parragon 2006 p.49.