The very large Trumpeter Swan is unlikely to be confused with anything but other swans. White Pelicans, Whooping Cranes, Wood Storks, and Snow Geese are all white birds that from a great distance could look like swans but all have black primaries. The adult Mute Swan can be told from the adult Trumpeter Swan by its orange and black knobby bill. The adult Trumpeter Swan is very similar to the adult Tundra Swan but it is slightly larger, has a straight culmen, the bill has no yellow spot, the eye is almost enclosed by black, and the white feathering on the head extends in a v shape into the dark bill. We will get back to you about the immatures!