Tweeters,

I looked in the Audubon Master Guide to Birding after reading this
description of Tundra and Trumpeter Swans. It appears to me that the guide
has a picture of a Tundra without the yellow spot in the section on
Trumpeters. I then looked in the Stokes Field Guide to Birds, as it also
has photos, and their photo of a Trumpeter is completely different from the
Master Guide adult Trumpeter. Please correct me if I am wrong.

Denny Granstrand
Yakima, WA

At 01:24 AM 3/17/97 EST, you wrote:
>Identification of these two swans can be tricky, especially for persons
>unfamiliar with one or both of the species. Characteristics often overlap or
>are subtle; even diagnostic characters can be difficult until experience is
>gained observing both species.
>
>When perusing flocks of swans for trumpeters, I generally look at the eye. In
>most tundra swans the eye is readily distinguishable from the the black
leathery
>extension of the bill (which meets the eye in a narrow point). This is further
>enhanced on the tundras that have the characteristic yellow spot. On trumpeter
>swans, the bill extension envelops the eye. If you were to look at the swan in
>a one-dimensional flat black and white context, the trumpeter swan eye
would be
>barely discernible from the bill extension, if at all. In the tundra
swan, the
>eye would appear as a large button, nearly separate from the bill extension.
>This works well even at a distance and will separate out most tundra swans
>quickly (but not all). From here, other standard trumpeter identification
>features need to be looked at and/or compared with obvious tundras. These
>other morphological or behavioral features (such as bill "V" notch, bill slope,
>neck kink, body size and posture) are too detailed to explain here.
>
>Tundra swans tend to hold there head (bill) on a horizontal plane with the neck
>held vertical. Trumpeters tend to have the bill pointed downward at a slight
>angle (for feeding or semi-alert birds only) and their necks are often
curved or
>bowed to some degree. While alert, tundras tend to nod their head or have a
>quick stiff neck bob returning the bill to horizontal and neck to vertical.
>Trumpeters exhibit a deeper head/neck bob resulting in a 'S' curved appearance
>to the head/neck, not the angular profile of the tundra. These differences
fall
>apart quickly depending on the alertness of the trumpeter.
>
>Other trumpeter clues include: small flocks or family groups separate or
on the
>periphery of a large flock of swans; trumpeters are generally dominant in a
>mixed flock, thus tundras tend to give way when a trumpeter approaches;
tundras
>prefer more open sites while trumpeters will use areas with enclosed vegetation
>or more visual barriers. By mid-winter, most immature tundras have attained
>their white plumage with only a scattering of light gray feathers remaining.
>Trumpeter immatures can remain quite gray into the spring and are
>near-diagnostic this time of year. Again all of these are clues of possible
>trumpeters and are not diagnostic. They are based on observations of swans in
>wetland situations and may not hold true for field-feeding birds such as in
>Skagit County.
>
>The Trumpeter Swan Society has published an identification pamphlet for
>distinguishing the two swan species. I published an article in UTAH BIRDS,
>Volume 6, Number 1, March 1990 that attempted to explain some of the subtle and
>distinguishing characteristics of the two swan species. While it needs some
>improvement, it may be useful. Unfortunately, I do not have either of these in
>a readily available electronic format but will send paper copies to interested
>persons if they email an address to me.
>
>Joe Engler
>US Fish and Wildlife Service
>Ridgefield, WA
>joe_engler at mail.fws.gov
>
>
>