Telling tundra swans from trumpeter swans is tricky, but based on guidance from the Sibley Guides website, I think this is a tundra swan. The narrow line of black connecting the black bill to the eye, and the U-shape of the line connecting one eye to the other, seem to confirm the identification; the connection is thicker and more V-shaped in the trumpeter swan.
I was pretty sure I'd been seeing a large group of lesser scaup at the pond during my previous visits, but certainly today they were ring-neckeds (the tall head with the strong angle at the back, and the very noticeable pale ring near the tip of the bill are key indicators).
|Tundra swan with female ring-necked ducks|
|Ring-necked ducks (male)|
We came back less than an hour later and saw the swan still there, but as I was pulling out my phone to alert a friend who lives nearby, it flew away. It's a good reminder that during migration (and really at any time) birds can come and go, so it doesn't hurt to check a good spot more than once a day if you have the chance. You never know what you might see.