The following galleries illustrate part of the variation in winter Kumlien’s Gulls. All photographs (or, actually, videograbs) were taken in St. John’s, Newfoundland (Canada) in late January – early February 2003 by Peter Adriaens.
All images are classified by age categories. When appropriate, birds were sub-categorized in “Typical”, “Pale”, and “Dark” types, to present the variation in a simple way.
Simply put, Kumlien’s Gulls are most similar to Iceland Gulls, with variable pigmentation in the primaries (and tail in immatures). The body can appear a little more bulky, head shape may be less rounded in a few birds (see e.g. images 46 in the ‘typical adults’ category for a bird with a sloping forehead), the bill can be slightly heavier (but still obviously short and small compared to e.g. American Herring Gull), and the wing projection may appear a little shorter at times (though the long primary projection is always quite obvious).
Typical: Most birds have a rather cold greyish or brownish colour, particularly on head, neck and underparts, which can be very uniform. The primaries usually vary from pale with brownish bases on the outer webs of the outermost feathers (also visible at rest) to rather plain brownish or greyish with pale inner webs and tips only. There is often a (pale) brown tailband; the tail can be almost fully dark in some.
Pale: A few birds have pale primaries (without brownish wash on the outer webs) and tail, much as in 1y Iceland Gull.
Dark: Some birds have (very) dark brownish outer webs, creating a (very) dark wingtip at rest. The inner webs to all primaries remain pale though. The tailband too is normally darker in such birds. In extreme cases, such dark types may appear similar to Thayer’s Gull, but their structure is still that of Iceland/Kumlien’s Gull. Thayer’s Gull is very rare in Newfoundland.
No extremely “pale” or “dark” types were seen, only birds with pale greyish/brownish or cold greyish/brownish primaries. All observed 2nd winter birds had already acquired a whitish mirror on the outermost primary (p10). Also, all had a greyish or brownish tailband.
Again, no extremely “pale” or “dark” birds were seen. The observed third winter birds had two white mirrors (p9-10), and usually a variable amount of grey/brown in the tail.
A few birds that had acquired large white primary tips, but still showed traces of immaturity on bill, primary coverts or primaries, were assigned to this age category. They could also be advanced third winter birds though.
Typical: In the majority of birds, the pigmentation in the primaries varied from pale greyish to dark blackish-grey. Some birds, at the paler end, had pale primaries with a darker greyish streak on the outer web of p10 only, or on the outer webs of p9-10. At the darker end in this sub-category, there were birds with dark markings on 5 primaries (p10-6). These had a very large white mirror on p10 (without any dark markings near the tip), and another large white mirror on p9 (interrupting the dark outer web, but separated from the white tip by a dark mark). The iris colour varied from very dark to pale yellowish.
Pale: Some birds had no dark pigmentation in the primaries at all – at least not visibly so in the field. Some birds of this pale type also had a pale iris; these could be either Iceland Gulls or pale Kumlien’s Gulls.
Dark: Some birds had blackish primaries, but their wingtip pattern was still as described above, except for two birds with a dark mark between the white mirror and the white tip on p10 (see adults 52 and 67).
For more information on the variation in adult winter Kumlien’s Gulls, and their separation from similar species and hybrids, see
Howell, S. & Mactavish, B. (2003). “Identification and variation of winter adult Kumlien’s Gulls”. Alula 9:1; 2-15.
Peter Adriaens : (firstname.lastname@example.org)