American Beavers and their signs are a common sight in Toronto's creeks and rivers. The Etobicoke Creek, Mimico Creek, Humber River, Don River, Highland Creek, and the Rouge River are all good places to look. Some places along the Toronto Waterfront are also good. I would imagine American Beavers would be common in Bronte Creek, Sixteen Mile Creek, and some places along the Oakville Waterfront.