Ringed Doppelgangers

I was happy to see a few Common Ringed Plovers on my trip to the UK. It is one of those species that must get overlooked on the east coast of the US. Even though they are likely a very rare vagrant, their identification is mired in their similarity with Semipalmated Plover.

Common Ringed Plover, Bolton, UK, May

I didn’t get long to make prolonged study, but a few things stood out:
– the paleness of the upperparts.
– blackish areas of the head were very contrasting, with prominent white  supercilium behind the eye.
– black joins bill at gape, but often closely matched by Semi-p (see picture below).
– overall shape was quite stocky, with rather angular head (lacking the rather smooth, rounded contours of Semi-p).
– primary projection (beyond tertials) seemed longer.
– lack of any narrow, obvious yellowish eyering.
– bill slightly larger and more ‘dagger-shaped’ with a more delineated black tip (roughly a tad more than  1/3 bill length).
– call was a low, slurred “poo-err”, quite low and unobtrusive, quite unlike the more emphatic and loud “chu-wee” of Semi-p Plover.

Semiplamated Plover, New York, August

Breast band, although touted as broader in Common Ringed (and it often is easy to see on some individuals) can be affected by posture and individual variation makes this of limited value in the field, e.g. there is little difference in breastband width of the two birds above.

On first glance, the pale upperparts, contrasting black portions of the face with noticeable white rear supercilium and rather less rounded head would attract attention. Further scrutiny of the head pattern to determine the shape of the black where it meets the bill and a presence of any eyering are the next clues to search for to clinch a putative ‘Ringer. There may be some subtle clues in the shape of the lower border of the earcovert patch and how far the white of the forehead patch extends down and in front of the eye on Ringed. Fuel for scrutiny. Of course, call and seeing palmations are nails in the coffin, but getting the coffin is the hard part – good luck on those two!

Common RInged Plover (front) and Semiplamated Plover (behind)

I’ve seen several Semi-ps with large breastbands, and despite large numbers passing through my patch in spring and fall, I feel confident that I’ve not seen a good candidate for Common Ringed in CT. With records from Massachusetts and a belatedly photographed adult from NY in September in the last decade, it is a species to keep an eye (and ear) out for.

Common Ringed Plovers are migratory and winter in coastal areas south to Africa. Many birds in Great Britain and northern Europe are resident throughout the year. There are three weakly-defined subspecies, which vary slightly in size and mantle colour; they intergrade where their ranges meet:

Charadrius hiaticula hiaticula – breeds temperate western Europe north to central Scandinavia; resident or short-distance migrant to southwest Europe. Largest and palest subspecies.

Charadrius hiaticula psammodroma – breeds Iceland, Greenland, northeast Canada; wintering west Africa. Intermediate in size and colour. Not sure if this would be possible in the field?

Charadrius hiaticula tundrae – breeds Arctic northern Scandinavia and Asia; wintering Africa and southwest Asia. Smallest and darkest subspecies.

Tundrae Common Ringed Plovers could conceivably occurr in the US. Since they are smaller, darker and shorter-winged than hiaticula they may prove more difficult to separate from Semiplamted Plovers.  Adult tundrae, unlike hiaticula, apparently do not moult during fall/autumn passage which may help separate them from hiaticula. Have to look into when adult Semiplamated Plovers commence wing moult to see if there’s any clues. See here for the great informative piece by Dave Norman:

http://www.davidnorman.org.uk/MRG/Walney%20Island%2030%20August%202003.htm

Final obvious advice….learn the calls. May the force be with you!

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