Common Merganser Identification, All About Birds, Cornell Lab of Ornithology
I saw a group of these ducks. Three what I assume males with black heads with one brown head assumed female. Are these mallard hybrids? : r/whatsthisbird
How to identify diving ducks | Herefordshire Wildlife Trust
Brown headed duck hi-res stock photography and images - Alamy
Winter Waterfowl Part Two: Diving Ducks | Lake Metroparks