Posted by Phil Pickering (208.46.229.59) on October 15, 2000 at 14:40:46:
Dave Irons makes some excellent points about structure. Even accounting for the foreshortened view, the bird on the left doesn't look quite right for an (adult) Bewick's, which look very flat-crowned, and should show a longer and more decurved bill. As Dave mentions, they also should look longer-legged and have more tarsi exposed, even when crouched. However, my guess is that this is a REALLY young bird that has yet to "fill out" to an adult-like structure. I think this would explain the structural anomalies Dave mentions, as well as the lack of a defined supercilium (also, after reading Alvaro's post I looked closely at the small visible section of the wing, and it does appear to have a wren-like pattern of complex cross-barring, although this might not be apparent on some monitors).
I think some of the anomalies mentioned for the Mac, such as the lack of definition to the lower edge of the bib, white in the supralores, asymmetrical eye arcs, and the smallish bill might also be traits of a very young bird (and I looked again very closely and can see no true streaking on the sides, just fluffed up feathers casting shadows).
After all, a point was made to mention that the photos were taken in August - a clue perhaps?
Phil