this guide can help you identify what waterbirds you see in Ontario
The common merganser (North American) or goosander (Eurasian) (Mergus merganser) is a large duck of rivers and lakes in forested areas of Europe, northern and central Asia, and North America.
The red-breasted merganser (Mergus serrator) is a diving duck, one of the sawbills. The genus name is a Latin word used by Pliny and other Roman authors to refer to an unspecified waterbird, and serrator is a sawyer from Latin serra, "saw".