Date: 3/7/17 4:53 pm From: David Irons <llsdirons...> Subject: [obol] Re: Swan ID (Ankeny NWR)
I would call this a Tundra as well. The complete absence of yellow at the base of the bill is not unusual in the sub-population of Tundra Swans that winters in the Willamette Valley.
Generally speaking, Tundra and Trumpeter Swans self-segregate into homogenous family groups within the larger flocks. If you watch them
for any length of time the family units become pretty apparent. When Trumpeters end up mixed in with Tundras they tend to be off by themselves at the margins of the flocks of the more numerous Tundras. While it is certainly possible for a single Trumpeter to be consorting with a group of Tundras (they are know to hybridize), it is far from typical behavior.
Finally, if you were to see a Trumpeter mixed in with Tundras there would likely be a noticeable difference in size, with the Trumpeter being larger and longer necked in general appearance.
This past Sunday at Ankeny NWR, after successfully chasing the Tufted Duck at Pintail Marsh despite icy winds and rain, Caleb and I headed over to Eagle Marsh for a quick check.
There were five swans in the water, one of which had no yellow on its bill. However, we concluded based on the shape of its facial features that it was still a Tundra Swan, and not a Trumpeter. Yesterday an eBird alert informed me of an as-yet-unconfirmed report of a Trumpeter Swan from the refuge, which I'm guessing was the same bird.
I'm still inclined to think ours was a Tundra Swan, but would be happy to know what more experienced birders think (and if we're correct, to warn others of this possibly misidentified bird showing up in eBird alerts). A photo of it appears in my eBird checklist here: