I think ruddy ducks might have been the original models for rubber duckies. They are small, plump, rounded, and toy-like. Bigger than robins. Smaller than crows.
This time of year they are non-breeding shades of tan and brown, making you wonder why they are called ruddy. (They get colorful in breeding season.) I've been seeing rafts of a dozen of so winter ruddies on the Delaware River near North Philadelphia for a few weeks.