Carp Creek swan


Peter Gaede
 

S.B. Birders:

I visited Carpinteria Creek this morning and spent some time photographing
the continuing immature swan just up creek from the railroad bridge. I was
able to study the head and bill features well at close range (see below),
but I just couldn't get past the small size of this bird for it to be
anything other than a Tundra. By this I not only mean the overall body size,
but the head, bill, and length of the neck as well. It was swimming next to
coots, and this helped to give some size perspective. Although separating
Tundra from Trumpeter can be tricky (especially immatures), I have found
that Trumpeters always appear strikingly large with long necks, and very
large bills weighted heavily towards the tip.

As discussed by Patten and Heindel (Birding, Oct 1994), certain features
that can be used to separate adult swans don't necessarily work with
immatures. These would include the "U" versus "V" on the forehead above the
culmen, and the straightness versus concavity of the bill. The Carp Creek
bird has a "V", as well as a forehead sloping into a relatively straight
bill, which are characteristics of adult Trumpeter swans, but features that
can be present on immatures of both species. The differences in adult versus
imm. Tundra swan head profiles has been illustrated quite well (in my
opinion) by Jonathon Alderfer on pg. 25 of "All the Birds of North America"
(American Bird Conservancy, 1997). I also noted that the length from the tip
of the bill to the gape was about 1.5 times that of the length from the eye
to the nape, a ratio that fits nicely for Tundra. The head also appeared
rather round, not as peaked towards the rear as I would expect for
Trumpeter.

Peter Gaede

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