To refresh your memory, here again is the photo for Bird Quiz #8. Read no further if you still want to have a shot at identifying these birds.
As I mentioned in the quiz, the top photo was taken in August, in Idaho. Actually, I was at the Camas National Wildlife Refuge, north of Idaho Falls. People were sparse—we saw one other person—but there were plenty of birds… Northern Harrier, White-faced Ibis, various shorebirds, and these swans.
I hope you recognized these as swans. The long, graceful neck, watery habitat, and white color makes that pretty clear. Other white birds in similar surroundings include Snow Geese and Ross’s Geese, but they have much shorter necks, orange bills, and obvious black patches on their wings, as shown here.
Narrowing our birds down to swans is a big step forward. There are four white swan species in our North American field guide: Mute, Trumpeter, Tundra, and Whooper. Both Mute and Whooper swans have significant amounts of yellow on their bills, so we can eliminate them. That leaves Trumpeter and Tundra swans.
My ID sources tell me that Tundra Swans usually have yellow on their lores (at the base of the bill near the eye). Here is another picture of one of these swans. No yellow. It’s probably a Trumpeter Swan. Can we be sure?
Sibley recommends checking the border where the bill meets the head, right between the eyes. On Tundra swans, the border is rounded; Trumpeter Swans have a pointed border, as seen on this zoo bird. Trumpeters also have a longer bill with a straighter base, but that’s really hard to tell when the bird is on the far side of a pond and you’re looking through a scope.
With no additional information, we can tentatively name these birds as Trumpeter Swans. Sometimes a probable ID is the best we can do. However, I was the one who took the photos, and I have additional information I didn’t give you. (Yes, I cheated.)
Here is another photo taken at the same time and place.
Checking the range, we discover that both species are present in Idaho—the Trumpeter is resident all year, but the Tundra just passes through on their way to the… tundra where they nest in marshes, rivers, and shallow ponds on the edge of the Arctic ocean. It’s August, so that doesn’t help—except that there were these juvenile swans present. That means the birds bred at Camas. And that means I’m pretty sure they’re Trumpeter Swans.