Tag Archives: gull

Dark 1st-cycle Kumlien’s Gulls

Peter Adriaens

 

With a fairly pale, putative 1st-cycle Thayer’s Gull in Scotland at the moment, now is probably a good time to look into some of the variation shown by Kumlien’s Gull.

The following photos were all taken at St John’s, Newfoundland, in late January 2013. They illustrate some of the variation at the darker end of 1st-cycle Kumlien’s Gull. Thayer’s Gull is still a rarity in Newfoundland, and the large numbers of Kumlien’s Gulls, all showing bewildering variation, make looking for one a rather daunting task!  However, given enough scrutiny, a typical Thayer’s Gull should still stand out, even when you have to sift through thousands of Kumlien’s Gulls.

This rather dark bird differs only subtly from paler examples of Thayer's Gull: it has already moulted many scapulars, the secondaries are greyish rather than dark brown, and the pale fringes to the primaries are slightly longer (reaching the secondaries at rest).

This rather dark bird differs only subtly from paler examples of Thayer’s Gull: it has already moulted many scapulars, the secondaries are greyish rather than dark brown, and the pale fringes to the primaries are slightly longer (reaching the secondaries at rest).

Compared to typical Thayer's Gulls, this bird shows less contrast between the outer and inner webs on outer primaries. Note that secondaries can appear darker than the greater coverts; this depends on the angle of the wing towards the photographer.

Compared to typical Thayer’s Gulls, this bird shows less contrast between the outer and inner webs on outer primaries. Note that secondaries can appear darker than the greater coverts; this depends on the angle of the wing towards the photographer.

This bird has rather pale secondaries, of the same colour as the inner primaries.

This bird has rather pale secondaries, of the same colour as the inner primaries.

This bird has moulted only a few scapulars. Note that the juvenile scapulars have quite extensive brown centers.

This bird has moulted only a few scapulars. Note that the juvenile scapulars have quite extensive brown centers.

The same bird, now with its wings open. Secondaries rather brown. Compared to most Thayer's Gulls, note the rather pale outer web to P6 (dark in Thayer's).

The same bird, now with its wings open. Secondaries rather brown. Compared to most Thayer’s Gulls, note the rather pale outer web to P6 (dark in Thayer’s).

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The above two pictures show examples of birds with extensive brown juvenile scapulars. However, rather than thin primary fringes as in Thayer's Gull, they show frosty whitish distal area on each primary.

The above two pictures show examples of birds with extensive brown juvenile scapulars. However, rather than thin primary fringes as in Thayer’s Gull, they show frosty whitish distal area on each primary.

This bird has rather dark juvenile scapulars.

This bird has rather dark juvenile scapulars.

This one has paler tertials than most 1st-cycle Thayer's Gulls (and has moulted many scapulars).

This one has paler tertials than most 1st-cycle Thayer’s Gulls (and has moulted many scapulars).

American Herring Gull – in the Netherlands?

Peter Adriaens

A subadult Herring Gull photographed in the Netherlands seemed very unassuming at first, but actually shows a key feature for American Herring Gull. This feature may not be what you regularly check in gulls, and is very easy to overlook…

When Leon Edelaar sent me the following pictures of a “herring gull sp.” that he had photographed at Ijmuiden, the Netherlands, on 2 February 2013, I was very hesitant to put a name to it. The pictures had been gathering dust on Leon’s hard drive, but they recently sparked his attention because he noticed a “grey mirror” on the underside of the ninth primary (see American Herring Gull: new ID feature), which made him wonder…

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Note oval-shaped, blackish patch on upper tertial.

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Note oval-shaped, blackish patch on upper tertial.

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Another view of the blackish ‘ink spots’ on tertials, from a different angle.

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Another view of the blackish ‘ink spots’ on tertials, from a different angle.

At first sight, the bird in the pictures did not strike me as very unusual. Surely, in shape and overall plumage aspect, it looked rather like any run-off-the-mill (subadult) European Herring Gull!? However, a closer look reveals a few interesting features. At rest, the bird shows quite impressive blackish and oval shaped ‘ink spots’ on the tertials, while the rest of the plumage looks basically adult. Many European Herring Gulls show dark marks on tertials, of course, but it is quite rare to see one that looks adult except for such large, oval shaped and well-defined, black(ish) spots. That is something much more commonly seen in American Herring Gulls. Then, in flight, the bird reveals an isolated grey spot in the black pattern on underside of primaries (at least in right wing). Again, this is more common in American Herring Gull. So far so good. An interesting bird, yes, but nothing impossible for a European Herring Gull. However, then we look closely at the secondaries, and they show the most alarming feature: two small but well-defined black ‘ink spots’. Such isolated black spots on adult secondaries are not seen in European birds, and have been considered a key feature of 3rd and 4th cycle American Herring Gull ever since the identification paper by Mullarney and Lonergan (2004).

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Black ‘ink spots’ on adult-like secondaries (here indicated by black arrows), and “grey mirror” on underside of P9 (white arrow).

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). Black ‘ink spots’ on adult-like secondaries (here indicated by black arrows), and “grey mirror” on underside of P9 (white arrow).

Other characters are less helpful. The primary pattern includes a complete, black ‘W’ on P5, and black “bayonets” on P6-7 (see Adriaens & Mactavish 2004) – good for American Herring, but equally possible for European birds. The tail shows a few small, solid black spots – better perhaps for American birds, as blackish markings in the tail usually do not look very solid in subadult European Herring Gulls. The bill shape and length look ok to me for either species, as does the colour of the upperparts. I would have expected heavier brown blotching on the neck and breast for an immature American Herring Gull, but there is a lot of variation.

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Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). The above four pictures show the primary pattern and pattern on tail.

Herring Gull sp., subadult, Ijmuiden, The Netherlands, 2 Feb 2013 (Leon Edelaar). The above four pictures show the primary pattern and pattern on tail.

So what does it all mean? It seems that, on current knowledge and for the time being, this bird should be considered an American Herring Gull, even though it is certainly not an obvious example! Here is one from North America that is similar:

http://gull-research.org/smithsonianus/smith4cy/4cyfebr012.html

The identification of such birds relies heavily on the pattern of the secondaries. There are many people closely studying and ringing gulls in the Low Countries, and it seems that such a pattern has never been documented in the local Herring Gulls.

If anyone has ever photographed such a secondary pattern in argenteus or argentatus, both Leon and me would be very interested to hear from you…