In the interest of improving my ID skills I’ve been studying these two nearly identical species. Both can be found in Washington in winter in large mixed groups, particularly in the Skagit Valley. I do see them in the Puyallup Valley regularly in smaller groups, but are often in locations that are distant from public rights of way (right of ways?).
The main difference between the species is size, with the Tundra Swan being a foot or more shorter from beak to tail. That can be difficult to discern in the field unless the birds are side by side in the same pose.
Another difference is the bills. Most Tundra Swans have at least a small yellow patch on their bill close to the eyes. The problem is that a significant number, ~10%, lack that feature. In addition, a small number of Trumpeter Swans have a similar light area on their bills.
I recently read a piece about how to identify these birds on David Sibley’s blog. Shape of the bill plays a big part in separating the two species. The biggest take away I got from his article is that the Tundra Swan’s eye is more defined because of the way the black of the bill narrows near its eyes. The Trumpeter’s eye appears to blend into the bill. I guess even more important is to look at the whole bird and note as many details as you can see.
But none of that can dampen the enjoyment of seeing such magnificent creatures in the wild.
Photo by Michael Brown