01/01/2010
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American and Pacific Golden Plovers

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Pacific Golden Plover, Azores, January 2008, by Dominic Mitchell
Pacific Golden Plover, Azores, January 2008, by Dominic Mitchell

 

Key featured species

  • American Golden Plover Pluvialis dominica
  • Pacific Golden Plover Pluvialis fulva
  • European Golden Plover Pluvialis apricaria


The two races of ‘Lesser Golden Plover’ – American and Pacific – were split by the BOURC in 1986, prior to which there had been only seven British records of Pacific. By 2005 the total had risen to 60, compared with 275 Americans. The latter occur in the same kind of habitats as their European counterparts and can often be found with them. Pacifics may also occur with Europeans but, equally, they may also be found on coastal mudflats in similar habitats to those frequented by Grey Plovers.

A quick analysis of the British records since the 1986 split reveals that, predictably, most Pacific Golden Plovers were seen in the Northern Isles and down the east coast, whereas records of Americans, although widely scattered, inevitably had a stronger westerly bias. There is also a marked difference in their temporal occurrence patterns: almost 70 per cent of Americans were found in September-October, having been swept across the Atlantic by westerly gales, whereas nearly 50 per cent of Pacifics were post-breeding adults in July-August. Both species showed a small spring passage from April to June and there were also a few winter records of each. Most surprising was how few juvenile Pacifics had been identified: just five specifically aged as such, all in September-November. Presumably they are to a large extent overlooked.

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Juvenile American Golden Plover

European Golden Plovers are not easy to age once they lose their summer plumage, as they all appear rather coarsely patterned and distinctly yellow. In contrast, juvenile Americans stand out because they are much less colour saturated, appearing cold, grey and colourless overall compared with Europeans. Their upperparts are delicately spangled with buff or white, lacking the strong yellow tones of juvenile Europeans, while their buff underparts are neatly and immaculately streaked and mottled.

The key feature to check is the underwing: on American, the entire underwing and axillaries are dusky grey, whereas both are conspicuously white on European. Also distinctive is American’s prominent whitish supercilium and dark crown, the latter producing a capped effect.

In direct comparison, American is smaller, slimmer and proportionately taller-looking than European. The most obvious structural ndifference is that the long primaries extend in a scissor-like manner well beyond the tail – another key feature to check. Equally important is the relative length of the exposed primaries compared with the overlying tertials. On European, the primary projection is about a quarter the length of the overlying tertials, whereas on American it is approximately equal in length to the tertials. Also, the tips of the tertials of American fall well short of the tail tip, whereas on European they fall closer to the tip itself.

The long-winged appearance of American Golden Plovers is related to the fact that, unlike Europeans, many undertake a huge trans-oceanic migration down the western Atlantic to wintering grounds in southern South America, from Bolivia and southern Brazil south into Argentina. Given this route, it is hardly surprising that this species is one of the most frequently occurring American waders on this side of the Atlantic.

Juvenile Pacific Golden Plover

Breeding as it does between European and American Golden Plovers, it is hardly surprising that Pacific is intermediate in appearance. Like American, it is noticeably smaller, slighter and proportionately longer-necked and longer-legged than European. In fact, it can look quite thin and lanky in ndirect comparison to European, except at rest or in cold weather when it appears more dumpy. European generally looks pot-bellied with shorter legs and neck. Pacific’s plumage is similar to European (although it is somewhat buffer toned) and it is distinctly yellower than American.

Compared with American, Pacific tends to look longer-legged and rounder bodied and perhaps also longer-necked, making it look somewhat front-heavy when feeding. It also has a longer bill, although there is overlap in measurements. In flight, the feet project beyond the tail to produce a more attenuated rear end (they do not project at all on American).

Pacific’s plumage is similar to that of European, being yellower than American’s (although it has somewhat buffer tones than the latter species). However, like American, it has pale grey underwings and axillaries –these should always be carefully checked when faced with a likely candidate.

Another major feature to check is primary projection:Pacific’s primaries do not project beyond the tail in the scissor like manner shown by Americans. Instead, the projection is much shorter, the exposed primaries being only about a quarter to half the length of the overlying tertials. Also, whereas the tertial tips fall well short of the tail tip on American, they are much closer to it on Pacific. The latter’s primary and tertial ratios are therefore much more similar to those of European.

In terms of plumage, Pacific can be separated from American by its lack of an obvious white supercilium and capped effect, as well as its yellower colouring.

In overall appearance, juvenile Pacific suggests a small,slim, long-legged, gangly, front-heavy European Golden Plover with grey underwings.

Calls

The American Golden Plovers I have heard sounded distinctly different from Europeans: a rising t-wee (described by Julian Hough in litt as reminiscent of Semipalmated Plover but “more mournful, less clipped”) and a mournful t-wee-loo (or koo-li-ooo) with the emphasis on the middle syllable.The Pacifics that I heard in Hong Kong in 1995 usually gave an up-slurred, drawn-out chu-wee, reminding me of Semipalmated Plover, or a more emphatic chu-it reminiscent of Spotted Redshank. However, they also gave quite a shrill toolee-oo, rising on the central syllable.

In preparing this article, I approached the subject afresh by listening to some recordings of calls. Hearing the three species together, I thought that American gave a shrill, squeaky, but rather slow, upslurred tu-wee(once down-slurred). To my ears, it recalled a squeaky swing. It also produced a  ‘thicker’, more urgent version of this: chew-it. Compared with European, the calls were higher pitched, less mournful and less haunting.

Pacifics gave a mellow but quicker, more cheerful and more urgent tu-weet, again with the second syllable up-slurred, or a tu-wee-u, with the second syllable upslurred and the third simply an insignificant lower-pitched note that was tagged onto the end. They also produced a quicker, more energetic tu-ick that sounded like a quick Spotted Redshank, but fuller and mellower.

Thus, although on paper the two species’ calls may seem similar, it was their quality and delivery that were different, American sounding slower and squeakier, Pacific quicker, more cheerful and more urgent.The latter’s ‘Spotted Redshank’ call was the most distinctive.

Pitfalls

A number of pitfalls need to be considered when distinguishing between American and Pacific Golden Plovers. One is that juvenile Grey Plover, before its winter body moult, may cause confusion: in terms of overall plumage tone it looks superficially similar to juvenileAmerican Golden. It too is delicately spangled across the upperparts, but both the upperpart spangling and the underparts may be distinctly yellow-buff in tone (although many are whiter). Grey Plover is, of course, a larger and bulkier bird than the three golden plovers, and it has a distinctly longer, heavier bill. It also shows a larger eye, with a somewhat blank ‘stare’, or vacant look, as well as thicker legs and streaked, not mottled, flanks. If in doubt, wait until it flies: the prominent white wing-bar, white rump and black axillaries make it instantly recognisable. Another problem can be caused by European Golden Plovers that have lost their tertials. As a consequence, such birds can look long-winged at rest, prompting thoughts of American. If in doubt, remember to check the underwing colour. Pacifics may also lose some of their overlying tertials, either through moult or accident, and then appear to have longer primaries than normal.

Like all birds, European Golden Plovers vary in plumage tone and some may be atypically pale and colourless, again suggesting American. If the bird has a distinct white supercilium, grey underwings and the correct primary tertial ratios, it is American. Pacifics can similarly vary: one that I saw in Hong Kong in April 1995 showed no yellow in the upperparts and buff underparts with only a faint breast band. In terms of plumage, it therefore bore a distinct resemblance to American.

It should be mentioned that, in the USA, some individuals have proved extremely problematical. Primary and tertial ratios have been hard to discern or they have not shown classic ratios. Some putative Pacifics have been atypically long-winged, similar to classic Americans, and such birds have even been referred to as ‘long-winged fulvas’ (Julian Hough in litt).

There is, of course, the possibility that such birds were American x Pacific hybrids, and O’Brien et al (2007) documented such a bird from New Jersey that apparently gave calls of both species. Hybrid American x Pacifics are probably highly unlikely to occur in Europe, but there have been examples of possible hybrids between Pacific and European Golden Plovers. There is little doubt that one such bird seen in north Somerset in winter 1987-88 would have been identified as a Pacific but for the fact that it had white underwing coverts.

It is easy to be put off by these problems but, as with any difficult species, it is important to adopt a holistic approach to their identification: consider all the possibilities, not just the most obvious – and some lateral thinking always helps!

Summer adults

In summer plumage, adult American Golden Plovers have much more extensive black on the underparts than European Golden Plovers do, the entire underparts of the males being solidly black all the way to the undertail coverts. A smartly contrasting area of white extends from the supercillium down the sides of the neck and bulges prominently onto the sides of the breast.Remember, however, that females may be less solidly black below, while moulting birds usually have a patchy mixture of black and white.

Like juveniles, summer adult Americans are greyer and less colourful above than Europeans, although closer views reveal fine but extensive pale yellow notching across the back and scapulars. By the time adults reappear in autumn, the brighter colours will have faded and such birds will look very ‘black-and-white’, with a striking thick white supercilium and a solid black cap, delicate whitish spangling and fringing across the upperparts, and patchy black underparts.

Summer adult Pacific Golden Plovers are more similar to ‘Northern’ Europeans, being yellowish above – although more coarsely patterned– and having the white supercilium, neck and breast stripe bulging less prominently into the breast sides than in American. Also, this feature extends narrowly right down the flanks, where it becomes rather messy due to the ntrusion of some black feathering. As in American, the black variably extends from the belly down onto the vent and undertail coverts, but the latter are only rarely completely black.

Note that both American and Pacific Golden Plovers do not complete their moult out of summer plumage until they reach their winter quarters and therefore retain variable amounts of black underpart feathering during their autumn migration. Also, whereas European completes its moult by September-October, both Pacific and American may retain traces of summer plumage well into the winter. So if you come across a late autumn or winter golden plover with remnants of summer plumage, it is always worth a second look.

In addition, Byrkjedal and Thompson (1998) state that, in adult American, the body feathers are moulted later than in Pacific. This is possibly useful in spring, since adult Americans at that time usually show a variable mix of transitional plumage as they head north. It is assumed from this that a full summer-plumaged bird in April would be more likely to be a Pacific (Julian Hough in litt).

First-summers

First-summer American Golden Plovers do not acquire full summer plumage, showing instead variable, but often limited, amounts of black feathering on the underparts. Many spring birds remain winter-like, being dull, colourless, worn and rather messy across their upperparts. The white supercilum is then the most obvious plumage character.

Pacifics, too, do not acquire full breeding plumage in their first summer (Cramp 1983). Such birds can be very tricky: for example, one transitional individual in Colorado in April 2007 proved very controversial, with respected observers split about its identity. Such birds may be particularly problematical as some plumage features, such as flank barring and vent colour, are ambiguous. The ageing of such birds may also be difficult, although it seems that Pacific retains its primaries through the winter whereas American moults its primaries on the wintering grounds. The logical assumption from this is that ‘first-years’ in spring with worn primaries should be Pacific, whereas those with relatively fresh primaries should be American (Julian Hough in litt).