Taxonomic status of
'Lesser Golden Plovers'
Alan Knox
I
n the past, there have been a number of suggestions that the two forms of
the Lesser Golden Plover, Pluvialis dominica dominica and P. d.Julva, might
warrant separate specific status. The situation was unclear, mainly due to
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Writ. Birds 80: 482-487, October 1987]
Taxonomic status of 'Lesser Golden Plovers'
483
the lack of evidence from detailed field studies. That difficulty has been
overcome to a large extent by several recent publications. After examining
the evidence, the British Ornithologists' Union Records Committee has
decided, on the recommendations of its taxonomic working group, to treat
dominica and fulva as separate species (BOURC 1986). The English names
suggested are American Golden Plover for P. dominica and Pacific Golden
Plover for P. julva. In this paper, I shall review briefly the taxonomic
problem, and outline the reasons for this change.
Fig. 1. Distribution of Pacific Golden Plover Pluvialis fulva (stippled) and American Golden
Plover P. dominica (vertical shading), both species breeding in the Arctic and wintering farther
south
Distribution
The Pacific Golden Plover breeds on the tundras of northern Siberia, from
the Yamal peninsula east to Chukotski, and across the Bering Strait in west
and northwest Alaska. In the latter region, it overlaps with the American
Golden Plover, whose range extends from northwest and north Alaska
eastwards over arctic Canada to Baffin Island {fig. 1). Small numbers of
dominica may breed in eastern Siberia, but proof of this is lacking, although
specimens have been collected there during the nesting season. The
evidence for breeding by dominica in Siberia was summarised by Portenko
(1981), but with undue weight given to uncorroborated statements and
inadequately documented records {see also Vaurie 1964).
The two Lesser Golden Plovers are extreme long-distance migrants,
travelling, in the case of fulva, to winter in northeast Africa, south and
southeast Asia, the central and southwest Pacific islands, Australia, New
Zealand and Polynesia. A few fulva now regularly winter in southern
California. The American species undertakes a loop migration to winter
mainly in south-central South America, from Bolivia and southern Brazil
south to Patagonia. In wintcr,fulva is often found in coastal areas, whereas
484
Taxonomic status of 'Lesser Golden Plovers'
dominica occurs largely away from the sea, on grassland and around inland
waters.
Taxonomy
Several early workers in the Bering Strait area had noted the apparent
overlap of the two Lesser Golden Plovers in Alaska and possibly eastern
Siberia. With the similarity of appearance of the two forms, especially
during the breeding season, it was difficult to determine to which taxon
some of the birds should properly be allocated. The issue was further
confused by reports of individuals with apparently intermediate characters.
These were assumed to have been hybrids and it was argued, quite
reasonably, that, if the forms were interbreeding with any regularity, they
were better treated as subspecies. It is perhaps surprising that more
attention was not paid at the time to the study by Conover (1945), since he
showed that the two forms overlapped in Alaska without hybridising. The
debate about intergradation continued, however (e.g. Gabrielson &
Lincoln 1959).
Recently, attention was drawn back to the subject by the decision of the
Checklist Committee of the Ornithological Society of New Zealand to split
dominica and Julva into separate species (OSNZ 1980). This was done on the
basis of apparent differences in moult strategy and the time taken to reach
maturity (Stresemann & Stresemann 1966), in addition to external
appearance and migration pattern (Sibson 1977).
The interpretation of some of these data has been controversial. The
Stresemanns (1966, pages 53 & 200) did not actually look at the moult of
dominica, only of Julva. They also quoted two authors who reported
(immature)/«foa summering in the wintering areas. Subsequently, Kinsky
243. American Golden Plover Pluvialisdominica, Cornwall, September 1980 (W. R. Hirst)
Taxonomic status of 'Lesser Golden Plovers'
485
& Y a l d w y n (1981) found large numbers of immature/tt/wz on the wintering
g r o u n d s in summer, lending support to the suggestion that julva did not
r e t u r n to their breeding habitats until IV2 or 2V2 years old, compared with
dominica, which were said to return after six months. Observations by
J o h n s o n & J o h n s o n (1983), however, differed in a number of respects from
those of Kinsky & Yaldwyn. T h e Johnsons noted that first-year/ttfoa could
be recognised in spring by their worn primaries, which were by then nine or
ten m o n t h s old. T h e adults, in contrast, moulted during winter, and had
fresh, u n w o r n primaries. Using these criteria to age Julva in Hawaii, they
found that, although some young birds over-summered in the winter
q u a r t e r s , m a n y did indeed return north. Johnson & Johnson were unable to
s u b s t a n t i a t e a stay of u p to 2V2 years in the winter quarters for 'most' Julva
(contra Kinsky & Yaldwyn). Primary wear was also examined in Alaska,
on specimens in breeding plumage (Connors 1983). As predicted by
J o h n s o n & J o h n s o n , Connors found a large number of first-year Julva; in
fact, his d a t a suggested to him that many moreJulva than dominica returned
after one winter. This was in contradiction to the views of the Stresemanns.
a n d Kinsky & Yaldwyn. Johnson (1985) was able to account for this
discrepancy. H e collected a small sample of migrant dominica in spring, and
showed t h a t birds aged internally as first-years had fresh primaries, as did
the adults. Although most first-year dominica return north to Alaska in
spring, they had not been recognised by Connors because of the differences
in moult betweenjulva and dominica.
C o n n o r s also examined birds collected in west and northwest Alaska and
found sympatric* breeding of Julva and dominica in an area 1,300 km across.
T h e r e were a few apparent intermediates, but he found the frequency of
intermediate plumages in the area of sympatry to be no higher than in areas
of allopatry* (Siberia; northeast Alaska together with C a n a d a ) . O n this
244. Pacific Golden Plover PluvialisJulva, USSR, September 1975 (Y. Shibnev)
*A sympatric breeding area is one in which two or more different populations are found
nesting alongside one another (in an area of sympatry). Where the populations do not
overlap, they are said to be allopatric. For further information see Mayr (1969).
486
Taxonomic status of 'Lesser Golden Plovers'
evidence, h e recommended that the forms be treated as separate species.
DeBenedictis (1984) argued against separation, saying that ' T h e main
evidence, the scarcity of intermediates, would also be observed between
subspecies which intergrade abruptly . . . and no samples come from the
actual zone of intergradation.' Connors' data, however, clearly weigh
against the existence of any hybrid zone. Indeed, they suggest that
intermediates in the area of sympatry are not of hybrid origin. Since they
are equally frequent in areas of allopatry, they are more likely to be part of
the normal range of variation of the pure types. Furthermore, an area of
s y m p a t r y 1,300 km across, running from almost pure dominica at one end to
almost pure fulva at the other, would scarcely be called an abrupt intergradation. T h e absence of samples from a short stretch in the centre of this
zone is unlikely to affect Connors' conclusions.
T h e differences between fulva and dominica in structure and plumage
(Pym 1982; Connors 1983; H a y m a n et al. 1986), moult (Johnson 1985),
migration pattern (no large-scale over-summering in the wintering areas
has yet been reported for dominica), and lack of interbreeding in areas of
sympatry (Conover 1945; Connors 1983) suggest that the two forms are
better treated as separate species. Connors (1983) and Johnson (1985) have
discussed t h e possible evolutionary history of the two taxa, and the
selection pressures on them.
T h e English names to be adopted by the B O U are those suggested by
C o n n o r s (following Kinsky & Yaldwyn). They are in agreement with the
4th edition of the A O U checklist (1931), although the 6th edition (1983)
uses Asiatic Golden Plover for fulva. 'Lesser Golden Plover' should be
avoided, to remove confusion with the old name referring to both forms.
T h e identification of the two species was discussed by Pym (1982, 1984)
a n d , in greater detail, by H a y m a n et al. (1986). T h e status of the two forms
in Britain a n d Ireland was reviewed by P y m (1982). Over 100 American
Golden Plovers have been found here, mostly since 1966. In contrast, there
are only a handful of records of Pacific Golden Plovers, the most recent
being in H u m b e r s i d e in J a n u a r y - F e b r u a r y 1985 (Brit. Birds 79: 544) and in
Lincolnshire in J u l y 1986 (Brit. Birds in press).
Acknowledgments
This paper is based on a report that was prepared for the BOURC. I am grateful to the other
members of the Committee and Lars Svensson for comments at that stage. R. B. Sibson kindly
sent me a copy of his note in Tara, which I was unable to locate in this country. I am also
indebted to Iain Bishop, Robert Hudson and John Marchant for valuable comments on the
manuscript.
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Dr Alan Knox, British Museum (Nat. Hist.), Tring, HertfordshireHP236AP