The American Golden Plover at Aiguamolls de l'Empordà, April 200: its identity under discussion
by Ricard Gutiérrez, & J.L. Copete

After RG having posted the announcement of the first set of images of this bird to different mailing lists, notably ID-Frontiers, some comments have been received doubting or confirming the correct identification of this bird. 

Basically, the question is a possible confusion with long-winged Pacific Golden Plovers Pluvialis fulva. And how do they look. Unlike dominica, the wing length in fulva is extremely variable and mostly population-based, such that birds breeding in NE Yakutia (approx., the NE coast of Siberia) have wings as long as dominica (recent translations from Russian papers, supplied to Martin Reid by James Barton). There appear to be a few published photos of long-winged birds - but not of European vagrants or Californian wintering birds, as they come from the shorter-winged populations on either side. A number of other characters, however, fit dominica rather than fulva.

Some other questions mentioned by people such as Martin Reid, Richard Millington, Eugene Archer, Carlos Gutiérrez Expósito, Karmelo, to whom we both thank, are treated below. 

Final comments by Steven Mlodinow, James H. Barton and Julian Hough clarify the status of the bird being a dominica:

JHBarton: "Friends, after examining the photos which Ricard shows, I would opine that the bird is "short-winged" American GP, P. dominica.  Ricard notes the ratio of the bill length to the distance between the base of the bill and the back of the eye.  This is a character cited by Byrkjedal and Thompson, in "Tundra Plovers"  I would also have expected a longer, thicker bill for Pacific, with noticeably more variation in thickness.  Ricard also notes the
tibia/tarsus ratio.  On Pacific, I would have expected a much taller bird with tibia and tarsus much more nearly equivalent in length.

Julian Hough: "...I would id it as an AGP rather than Pacific 
because:
- the pale notches on the summer upperpart feathers are small, not large as in PG, resulting in a denser, heavier look to the spangling.
- the black feathers coming in along the flanks, adjacent to the wing, is more in line with AGP, since alternate PGP is likely to be paler here with any dark markings being barred in pattern.
- the bill is slight, not broad based as in PGP.
- legs do not look overly long as in typical PGP, which often look like knitting needles to my eyes.

These photos complete the set already published in the previous page.

All photos show a putative first-summer American Golden Plover Pluvialis dominica videoed at Matà rice-fields, Aiguamolls de l'Empordà Natural Park, Girona, Catalonia, NE Spain on 18.4.2001. Photos are videocaptures of a recording done using a Panasonic NV-EX3 digital videocamera manually attached to a Kowa TSN824 telescope by Ricard Gutiérrez. Original captures were 640x480 sized and were created using an Avermedia Aver TV card connected via S-Video out plug to the camera, thus not via direct i-link plug due to lack of enough resources in RG computer. No changes in colour nor sharpening treatment have been applied to images.

Notice the dark flank feathers already coming through which is a feature less likely to be present on fulva. Especially look at the black new feather just in the wing edge in a place where fulva should have a white pannel. Spotting on upperparts including wing coverts is small ( should be % bigger on fulva, and fewer on wing coverts). Also the golden spotting seem to be closer to that of dominica rather than to fulva.
Los flancos presentan plumas negras en zonas que en fulva habrian de ser blancas. Además, el moteado en este ejemplar es más próximo a dominica: fulva tiene las manchas más gruesas. 
Els flancs presenten plomes negres en zones que en fulva haurien de ser blanques. A més, el motejat en aquest exemplar és més proper a dominica: fulva té les taques més gruixudes.

This bird shows a small, fine bill (comparatively longer and thicker on fulva). The apparent dark forehead just above bill should be a dominica character (white on fulva to bill base). See Dunn et al. 1987.Field identification of forms of Lesser Golden-Plover. International bird identification, Eilat : 28-33
Además de un pico fino que es más largo y gordo en fulva, se insinúa una banda negra en la frente, de bastante grosor, carácter típico de dominica (ver asimismo la referencia que aparece en el texto inglés). 
A més d'un bec fi que és més llarg i gruixit en fulva, s'intueix una banda negra a la front, bastant gruixuda, caràcter típic aquest de dominica (vegeu la referència que apareix al texte anglès).

The longest tertial of the bird has to regrow. But it is doubtful if it would regrow long
enough to match up with the tail tip (as it does in fulva). It is worth remembering when talking about primary projection/formula on these plovers, it is different in adults (less pronounced) than in 1st years. However, other authors quote that the fact that the tip of P4 is visible beyond the tertials does not rule out fulva; the oft-quoted "rule" is fulva usually has 3  but sometimes 4 tips, while dominica usually has 5 tips, but often only 4.  Anyway, it seems that the wing seems long-enough for dominica, but what about those long-winged fulva.Supporting characters should play a more important role in this bird ID.
Resumiedo lo que dice en inglés, aunque las terciarias estan gastadas, parece que aunque estuviesen crecidas del todo tampoco tendrian la longitud de un fulva
Resumint el text anglès, sembla que tot i que les terciàries estan gastades, sembla que tot i que fossin noves, tampoc tindrien la llargària d'un fulva.

Measurement of the bill length (tip, to feathering at base of culmen) and 
for this to be "folded back" from the culmen base to see how far it reaches 
over the eye seems to be a clue for ID. If reaching obviously behind the rear edge of 
the eye is a strong fulva feature. Note 1: rear eye edge; 2: bill feathering base, 3:bill tip. The bill of the bird has been copied from the photo and "folded back". It does not reach obviously behind the eye: thus, a dominica character. Although it should be seen if this is the most convenient angle.
Medida de la longitud del pico (punta/plumas) y el mismo pico hacia el ojo para ver si la distancia punta (3) -plumas (2) es mayor que la (2) - ojo (3). Parece que no, lo que indicaría carácter de dominica.
Mesura de la llargària del bec (punta /plomes) i el mateix bec cap a l'ull per veure si la distància punta (3) - plomes (2) és més gran que la (2) - ull (3). Sembla que no, pel que indicaria un caràcter de dominica.

Primary projection: this animal has longer primaries than a fulva seen by one of the observers in the Ebro Delta in 1996. Primaries were level to tail length. This bird has a long wing well longer than tail. Notice that some tertials appear not to be too worn.
Proyección primaria: este animal tiene las primarias muy largas en comparación a
lo que debería ser un fulva típico. El que se vió en el delta del Ebro en 1996 tenía a los sumo 3 primarias, que sobresalían muy poco detrás de la terciarias, y asimismo quedaban a la misma altura del final de la cola. Este ave tiene un ala muy larga, que sobresale mucho de la cola. Fijaos en las terciarias que algunas no están gastadas.
Projecció primària: aquest ocell té les pp molt llargues en comparació a un fulva vista al delta de l'Ebre el 1996. En aquell les pp estaven a l'alçada de la cua. En aquest no, l'ala és més llarga. Algunes de les terciàries, a més, no estan tan gastades.

Further views of head/bill shape and mantle/feathering
Más vistas de la cabeza/ forma del pico y manto/plumaje del dorso
Més vistes del cap/forma del bec i dors/plomatge.

This bird, despite longer-legged than an apricaria, had a realtive shortish tibia (which should be longer compared with tarsus on fulva). This is obvious in this shot where exposed length of tibia is considerably shorter than tarsi. Again, comparing with bibliography e.g. Vinicombe & Cottridge 1996 this would fit dominica.
Patas:  el fulva del delta del Ebro aparentaba mucho más patilargo (especialmente en tibia) que un apricaria o un squatarola, en comparación. Este de Aiguamolls también, pero no tanto como el que se vio allí.Comparando además la longitud de tarsos y tibias con fotos (por ej. lo que sale en Vinicombe & Cottridge 1996), también se acerca más a dominica que a fulva. Además fijaos en la longitud relativa tibia/tarso
Potes: aquest ocell tot i ser potallarg, més que un apricaria, té unes tibies relativament curtes, en comparació a fulva, fet que d'acord amb bibliografia parlaria de dominica.