Date: 3/7/17 1:34 pm
From: Tom McNamara <tmcmac67...>
Subject: [obol] Re: Trumpeter v. Tundra Swan ID: The eyes have it!
Hi all,

Good link, Dan. Here's another that has been adverted over the years on
OBOL ...and remains a good one or identifying the several species (includes

good birding,

On Tue, Mar 7, 2017 at 12:10 PM, Anne & Dan Heyerly <tanager...>

> Obolinks,
> With all the variation of yellow/no yellow lores, “U” vs. “V” forehead
> feathering when the swan is directly facing you, or is the bill concave or
> straight (profile)? The discussion up to this point centers around those
> three things, but in my opinion neither is always distinct as a thing. Two
> weekends ago Anne and I birded in the Skagit River area north of Seattle,
> where a good number of both Tundra and Trumpeter Swans were present. We
> came to rely on looking at the eye for identification of these birds.
> Trumpeter’s broad black connection of the eye and the mask was what we
> focused on, or as David Sibley says in a Feb. 19, 2006 article on the
> Sibley Guides website (
> trumpeter-and-tundra-swans/), “*the Trumpeter’s eye is broadly connected
> to the black bill, whereas the Tundra’s eye appears nearly separate from
> the bill. The Tundra Swan illustrated is one of the approximately 10% of
> all adults that show no yellow on the lores. The separation of eye and bill
> is even more pronounced when any yellow is present. On juveniles the
> feathering is more extensive than on adults, and therefore this feature is
> more variable, but probably still useful. The V-shaped border on the
> forehead of Trumpeter Swan (vs U-shaped on Tundra) is useful, but can be
> hard to judge and some birds appear intermediate.*”
> To me, another way of looking at this is to think of the appearance of the
> Tundra’s eye as sort of “pinched off” from the black connecting the eye to
> the bill, whereas a Trumpeter’s dark eye simply expands directly to the
> bill with no “pinching” (“. . . broadly connected to the black bill” – D.
> Sibley).
> Whether the bill is straight or concave, is the forehead feathering a “u”
> or a “v”, how large is the bird, etc. are all field marks, but all are
> variable depending on which way the bird turns its head (except for size of
> the bird, which is not wise to rely on unless you are certain both species
> are present to compare). It’s sort of like relying on the black and white
> markings on dowitcher tails. Not 100% reliable! When we found a mix of both
> in a flock, which was not a common occurrence, our identifications were
> confirmed when they “spoke”.
> Good Birding,
> Dan Heyerly, Eugene

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