Fig. 1 - Pacific Golden Plover (click to enlarge)
© Andrew Baldelli
Fig. 2 - Pacific Golden Plover (click to enlarge)
© Andrew Baldelli
Both photos show the very short extension of the primaries
beyond the tail. At the time, Ash and I estimated the extension
to be 3mm. Figure 1 also shows the very long tertials and
the very short extension of the primaries beyond them.
Although they cannot be seen in the photo, in the field
we counted 2 primaries visible beyond the tertials, as
we were not able to discern the two longest primaries as
separate. In other words, this bird actually had three
primaries extending beyond the primaries. The blunt rear
end of the Mecox Bay bird is also visible in the photos,
especially Figure 2. In our brief observation of the bird
in flight, we were unable to note if the toes extended
beyond the tail. As for the overall appearance of the bird,
it looks large bodied to me, but I’m not sure that
I can claim that it is small headed or slender in the neck.
In summary all of the structural characters that were observed
indicated Pacific, and none of them favored American.
We did not hear the bird vocalize so only the plumage characters remain for discussion. It is difficult to assess the status of the flank stripe in the Mecox Bay bird since it was in a transitional plumage. However in Figure 2 a flank stripe can be imagined and the presence of gray feathers in the area is consistent with Pacific. Figure 2 shows the pure white undertail coverts. Although winter-plumaged American could show this mark, in my experience American in transition from breeding to winter plumage always show some remnants of the black feathering in the undertail coverts. In both photos the gray coverts produce a pale patch on the folded wing. Both photos show that the black patch through the eye is paler and more diffuse than would be expected in American. The plumage characters of the Mecox Bay had states that indicate Pacific or are consistent with it. In summary, the both structural and plumage characters indicate that the Mecox Bay bird was a Pacific Golden-Plover. While there are a few character states that are consistent with both species, there are none that indicate American Golden-Plover. The two species are not known to hybridize.
Prior Occurrences and Distribution
There are three accepted prior records from the eastern United States, two in fall (both in the first half of September) and one in spring. A bird was shot at Scarborough, Maine on 11 Sep 1911 (Palmer 1949). The second record was of a bird in transitional plumage (from breeding to winter) in Cumberland and Salem counties (it flew back and forth), New Jersey from 4-16 Sep 2001 (Crossley 2002). The third record was from Plum Island, Massachusetts, 21 Apr to 5 May 2002 (Heil 2003). There is also a report of one from Delaware in late September or early October 2003, but I haven’t seen any details on this sighting. In addition, Crossley (2002) reports three records from Greenland (all immatures), one from Bermuda and two from Barbados.
Pacific Golden-Plover is a rare but regular fall migrant, and a casual spring migrant in all the Pacific Coast states. It is a very rare, but annual, winter visitor in California. Away from the coast there are several records for inland California, inland Washington, Alberta, Idaho, Nevada and Arizona (P. Lehman, pers. comm.). In western Europe it is a casual vagrant in fall (Jonsson 1993, Mullarney et al. 1999).
The Pacific Golden- Plover is a long distance migrant that breeds
on the tundra of eastern Siberia and western Alaska. It nests
along northern coastal Siberia
from the Yamal Peninsula (70 degrees East) eastwards to far western Alaska. In
Alaska it can be found nesting from Point Hope south through the Seward Peninsula
to Kuskokwim Bay where it is sympatric with breeding American Golden-Plover (Byrkjedal & Thompson
1998). Pacific winters from the horn of Africa east to eastern Oceania, and there
is also a small group that winters in California annually. The primary wintering
areas are the eastern Indian coast, Bangladesh, southeast Asia, eastern Australia
and Oceania (Byrkjedal & Thompson 1998). Thus it is not unexpected that a
few Pacifics might get mixed in with flocks of Americans and head south with
them, and they might be likely to turn up anywhere in North America. The fact
that three of the records have occurred since 2000 may be a function of the rise
in popularity of digiscoping and the availability of detailed information that
is applicable in the field. It was not long ago that Pacific Golden-Plover and
American Golden-Plover were considered very difficult to separate even in the
Until recently, both were considered races of a single species P. dominica. Connors and his associates have demonstrated that in the area of sympatry in western Alaska both occupy different habitats even when their territories are adjacent (Pacific prefers wetter tundra, American drier sites). In addition, they have behavioral mechanisms (mainly in the form and use of flight songs and calls) that prevent interbreeding. Indeed no instances of mixed pairings were observed in Alaska, despite the proximity of nesting pairs to each other (Connors et al. 1993). When two populations are sympatric and do not interbreed, they must be valid species. Thus by the early 1990s, Pacific Golden-Plover was accorded species status by the AOU. The use of wetter tundra and shoreline habitats by Pacific has apparently affected its evolution, and has given rise to several of the structural differences that are used as field marks for separating the two species. Pacific’s longer legs and longer bill would have obvious selective advantage in littoral habitats.
I wish to thank the following people. P.A. Buckley,
Thomas Burke, and Anthony J. Lauro provided crucial assistance
while we were observing the bird that allowed us to make the identification.
Subsequent discussion with all three of them has been invaluable
in completing this note. Paul Lehman provided information on the
New Jersey record and on the status of Pacific Golden-Plover throughout
North America. Rick Heil forwarded a copy of his paper on the Massachusetts
Byrkjedal, Ingvar & D.B.A. Thompson. 1998. Tundra Plovers: The Eurasian, Pacific and American Golden Plovers and Grey Plover. T&AD Poyser, London 422 pp.
Chandler, Richard J. 1989. North Atlantic Shorebirds. Facts on File, New York. 208 pp.
Connors, P.G., B.J. McCaffery & J.L Maron. 1993. Speciation in Golden Plovers, Pluvialis dominica and P. fulva: Evidence from the Breeding Grounds. Auk 110:9-20.
Crossley, Richard. 2002. New Jersey’s First Pacific Golden-Plover. Records of New Jersey Birds 28(3):57-60
Hayman, Peter, John Marchant & Tony Prater. 1986. Shorebirds: An Identification Guide. Houghton Mifflin Company, Boston 412 pp
Heil, Richard S. 2003. Three New Species for Massachusetts from Plum Island in 2001-2002. Bird Observer 31(2)
Jonsson, Lars. 1993. Birds of Europe with North Africa and the Middle East. Princeton University Press, Princeton, NJ. 559 pp.
Mullarney, Killian, Lars Svensson, Dan Zetterstrom & Peter J. Grant. 1999. Birds of Europe. Princeton University Press, Princteon, NJ 402 pp.
Palmer, R. 1949. Maine Birds. Bulletin of the Museum of Comparative Zoology 102:1-656.
Sibley, David Allen. 2000. The Sibley
Guide to Birds. Alfred
A. Knopf, New York 544 pp.