The most striking feature was the state of feather wear. The wing coverts were worn almost white and the tertials were so worn as to have pieces missing. Even in flight we could pick out the bird by the pale uppersurfaces of the inner wings. In contrast, the adult American Golden-Plovers (P. dominica) were much less obviously worn although showing various degrees of body feather molt. At present, I'm not sure how to explain the plumage state of the proposed Pacific Golden-Plover. Could this be a second year bird? According to Byrkjedal and Thompson (1998, see below), the body feather molt of adult American Golden Plovers tends to occur slightly later than in Pacific Golden-Plover, so one might expect a Pacific Golden-Plover to have replaced more body feathers. Does this timing apply to wing coverts?
The bill length was useful in pinning down the Pacific Golden-Plover. It seemed slightly longer and distinctly shallower than the accompanying American Golden-Plovers (see below). The flanks were pale gray with heavy near-vertical black barring.
For comparison, here is a spring adult Pacific Golden-Plover in alternate-plumage (above). The bill on this bird seems even shallower than the New Jersey individual.
Videograb showing a close up of the folded primaries and tail. The primaries were no more than a fraction longer than the tail and only two or maybe three projected beyond the long but frayed tertial tips. This profile contrasted strongly with the very attenuated look of both adult and juvenile American Golden-Plovers. On the American Golden-Plovers it was not difficult to see that the primaries extended well beyond the tail tip and at least four primaries were evident beyond the tertials.
Close-up of the frayed tertials and less obviously abraded primaries.
The Pacific Golden-Plover had a more obvious golden tint to the mantle and scapulars. This was evident at a good distance and over a range of light conditions. Likewise, the crown showed more color (golden speckles) than on the adult American Golden-Plovers which showed a more uniform dark cap.
Two views of the largely unmarked undertail coverts and vent as the bird dips forward.
The band of dark feathering running down the hindneck appeared broader (not narrower as stated in earlier version of this page) than on the American Golden-Plovers. Even accounting for wear this seems an interesting difference. Notice also the rich gold tones to the scapulars and mantle feathers.
Although disturbed a couple of times by workers from the farm, the plovers were relatively silent and we did not detect any calls from the Pacific Golden-Plover.
There is a large literature on the
identification of Golden-Plovers, primarily from Europe. A phenomenal source
of information is "The Tundra Plovers: The Eurasian, Pacific and American Golden
Plovers and Grey Plover" (1998) by Ingvar Byrkjedal and Des Thompson, T &AD
Poyser Press. This is a must for any shorebird lover!
Obviously, we would all be interesting in counter-arguments or comments for those with extensive experience of Pacific and American Golden-Plover. This is never an easy identification. Ultimately the final call rests with the finders and the New Jersey Records Committee. Supporting documentation should be submitted to the NJBRC by everyone lucky enough to enjoy this bird.
Acknowledgments: Congratulations to Crossley, O'Brien and Obercian for an astounding find! The differences described above as subtle and hard to notice on a quick scan of a distant flock of Golden-Plovers. I am mightly impressed! Many thanks also to the New Jersey folks, especially Laurie and Shawneen, for excellent directions and daily updates.