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Re: Salem "Trumpeter Swan"

hi Cliff,

I'm afraid I must respectfully disagree with your assessment. I believe that
the bird is correctly identified as a trumpeter swan, and for the following
reasons. I will use web-based images of birds taken by various photographers
that are identified as juvenile trumpeter swans (hoping that they have been
correctly identified) to support my arguments.

1. According to Sibley, juvenile trumpeter swans have a bill that is "always
black at base" whereas tundra swans have a bill that is "pink at base,
becoming black." Examples of this can be seen at
http://www.eimagesite.net/s1/gst/run.cgi?action=imagen&prid=310 and to a
lesser extent at
http://www.schmoker.org/BirdPics/Photos/Waterfowl/TRUS_TUSWcomp1.jpg. In this
respect these birds appear similar to the bird illustrated to Sibleys and also
to the Salem swan.

2. The head shape of trumpeter swans differs from that of tundra swans. In
this I refer to the "Identification of Swans" item in Sibleys, and also to an
online article authored by Kevin McGowan entitled "Swan Identification in
upstate New York" found at http://www.birds.cornell.edu/crows/SwanID.htm. Dr.
McGowan, who spent a number of years as the curator of the birds and mammals
collection at Cornell University, articulates the differences in head shapes
in the following words: "Trumpeters have a longer, flatter bill, and a more
flattened profile and head shape (somewhat Canvasback-like).  Tundras have
more rounded heads and slightly concave bills." Having actually watched the
bird for a number of minutes, as opposed to finding it necessary to rely
solely on photographs, I believe the head shape of the bird - which can be
seen in the middle photo at
http://utahbirds.org/hotlinephotos/TrumpeterSwan.htm - is more clearly
consistent with that of a trumpeter than of a tundra swan.

3. In adult birds, according again to Dr. McGowan, "the eye of a Trumpeter
looks contained within the black mask of the face, while the eye of a Tundra
looks nearly separate, connected only by a small area directly in front of the
eye.  (This connection can look even narrower because of the yellow lores.)
At a quick glance, you can see the position and size of a Tundra Swan's eye
easily, while that of a Trumpeter is more hidden." Unfortunately Dr. McGowan
does not address the extent to which this is true in juvenile birds and how
age might play a role in this aspect of the bird's appearance. I would again
refer you to the images mentioned in 1. above, and also to
http://www.schmoker.org/BirdPics/Photos/Waterfowl/TRUSjuv3.jpg. Assuming these
birds are correctly identified as trumpeters, it seems apparent that in
juvenile birds, the black mask is less reliable in differentiating between the
two species than in adult birds.

4. I'm not familiar with your observation that begins "edge of feathering,"
although I do not doubt its correctness. As to the bill-forehead connection,
Sibley says simply that in tundra swans there is a "rounded border" whereas in
trumpeter swans there is a "pointed border."  As to this McGowan elaborates
ever so slightly more, stating with reference to a photo about 2/3rds of the
way down the page "this is the only forehead shot I have, showing the shallow
"U"-shaped forehead of a Tundra Swan.  A Trumpeter would have a more V-shaped
look with a pointed front border of white into the black, formed presumably by
the the more swollen area above the nostrils." In my opinion this is
illustrated quite clearly in the bottom photo of the Salem swan found at
http://utahbirds.org/hotlinephotos/TrumpeterSwan.htm, especially when compared
to the McGowan photo of the tundra swan forehead.

5. As for the matter of flat backs versus arched backs, Sibley states that in
trumpeter swans "back tends to be more evenly rounded than Tundra [swans]."
McGowan does not comment on this attribute. I have no doubt that you have seen
far more of each specie than I have, Cliff, but to me this extent of roundness
versus flatness seems to be rather a subjective identifier, i.e., one subject
to the interpretation of the observer. In looking at the images sited above
and on McGowan's page, I have to confess that I would find myself extremely
hard-pressed to differentiate between the species shown on his page based
solely on the extent of back-arch. In addition, I find myself wondering if
this is always consistent, even within the same bird. Primate postures can
change, depending on how animal is carrying itself. One simply has to watch
men on a beach, trying to impress women, to see this changing of postures at
work. Is this also possible in birds? If so, how ultimately reliable is back
shape in swan species differentiation?

6. Coloration seems to indicate that the bird is a juvenile bird, but how far
can this be taken? If the Salem bird was born a few weeks earlier or later
than the Island Park birds you observed, is it not possible that its
coloration would be somewhat out of phase with those birds? And are there
other factors, such as genetics, diet, and etc. that might also play a role in
the coloration of a juvenile bird at this time of year? I question the value
of coloration in juvenile as an objective identification tool in
differentiating the species.

Cliff, I have followed your posts for a number of years, largely on the Idaho
list, and I have a great deal of respect for your opinions. I welcome your
feedback, and that of the group if anyone else is interested, and will happily
admit that I am wrong if you can prove me incorrect to my satisfaction.

Lu Giddings

october@ida.net wrote:

> I viewed the photos of the juvenile swan at Salem, as well as Nicky
> Davis's photos of the same individual, and feel strongly that this is a
> juvenile Tundra Swan.  Here are my reasons:
>
> -Bill is pink with black base and tip, typical of juvenile Tundra Swan but
> not typical for Trumpeter.
> -Eye appears separate from bare skin of bill, consistent with tundra Swan.
>  On Trumpeters the eye looks like it's included in the bare/black
> extension of the bill.
> -Edge of feathering along bare skin at base of bill has sharp curve.  This
> is difficult to explain but the shape of the junction between feathered
> head and unfeathered (bare) base of bill differs between species.  If you
> follow this edge from the eye towards the bottom of the bill, about half
> way (or maybe 2/3 of the way) out it makes a sharp downward curve then
> continues more or less vertically to the bottom of the bill.  Trumpeter
> Swan has a more gentle curve and doesn't usually look vertical anywhere
> along that junction.  I sent some photos of a Trumpeter for comparison of
> this feature and eye placement to Nicky Davis a couple days ago; hopefully
> they'll be posted later today).
> -Back is more arched than on Trumpeter (which is flatter) and consistent
> with Tundra.
> -Wing coverts are white.  Tundras molt wing coverts sooner than Trumpeters
> and appear very white backed this time of year.  Trumpeters still look
> mostly brown (I checked ten or so juveniles in Island Park two days ago
> and they all still had brown wing coverts).
> -Neck seems a bit short and thin for Trumpeter but this is hard to judge
> with no Trumpeters for direct comparison.
>
> I just thought of some photos that may help.  They're posted at
> http://www.octoberweb.com/birds/whooper/.  The top photo shows two
> juvenile Trumpeters for bill color comparison.  It's hard to make out the
> edge of the bare parts on this photo, but if you look hard you can sort of
> make it out.  Eye placement is sort of visible on the right bird.  The
> second photo show a Trumpeter and a possible Whooper Swan in which you can
> see the shape of the back of Trumpeter as flatter than the Salem bird.
> This is also noticeable on the right Trumpeter in the first photo.
>
> I'd be interested in what others think about these points.
>
> Cheers,
> Cliff
>
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