glaucoides - kumlieni

(last update: January 26, 2012)

Kumlien's Gull (kumlieni) 1st cycle - 6th cycle, 2022, Julianadorp, the Netherlands

Pictures winter 2016-2017 (1st winter): HERE, HERE & HERE.

winter 2017-2018 (2nd winter): HERE, HERE, HERE & HERE (already with obvious pale iris).

winter 2018-2019 (3rd winter): HERE (April).

winter 2019-2020 (4th winter): HERE, HERE, HERE, HERE, HERE & HERE.

Pattern on the outer primaries was most obvious in 4th cycle (images of 5CY January), when we wondered if the pattern would still be visible in next years, which apparently is the case. As 4th cycle it had a very pale staring eye (in fact from the 2nd winter -Febr 2018- onwards).

This bird should be regarded kumlieni (depends on the definition of kumlieni of course), but in general, even the palest kumlieni still have any "shade of grey" (not necessarily charcoal black, any shade of grey will do) along the outerweb of P9 and P8, plus some sub-terminal markings returning on the outer primaries, that should be 'beyond the limits for glaucoides' - and from a reverse point of view, in Canada, where glaucoides is a rarity, birds with pigmented primaries are rejected as glaucoides, and automatically (and safely) placed within the kumlieni range.

From a European view, the staring yellow iris and pale silvery grey upperparts have a better match for glaucoides than they have for kumlieni. Also, the plumage in previous years (immature plumages) didn't hint to anything different than glaucoides.

In Iceland, adult Iceland Gulls with the slightest primary pigmentation along the shaft and/or subterminal patterns are considered kumlieni. According to Stefán Ragnarsson, who adopts the simplest approach, it's rather easy and avoids confusion: "If I would call your bird in Holland a glaucoides, then the line between kumlieni and glaucoides becomes even blurrier".

It seems the area of pigmentation in the wingtip decreases slightly with age.

below: Kumlien's Gull (kumlieni) 6th cycle - 7CY, February 15 2022, Julianadorp, the Netherlands. Picture: Mars Muusse.

Age is adult winter in 2021 (5th cycle / 6CY) and 2022 (6th cycle / 7CY), lacking brown wash on primary coverts, which was still present in 4th cycle - January 2020.

Wingtip darkness score: 2 - medium grey (Estimated Kodak 7-10). In the study by Howell & Mactavish, about 77% of Kumlien's Gulls in New Foundland belong to this category, see Table 1.
Wingtip scoring for dark markings on P5-P10: 0-0-0-1-3-1. See Plate 1 for explanation.
Wingtip pattern category: Type D, Stage 2, darker grey marks on the outer three to four primaries with subterminal marks on one to three primaries. See primary patterns for explanation. In the study by Howell & Mactavish, about 11% of Kumlien's Gulls in New Foundland belong to this category, see Table 2.
Iris colour variation: 3 - apparently unmarked pale yellow (like an adult Herring Gull but typically slightly darker yellow). In the study by Howell & Mactavish, about 19% of Kumlien's Gulls in New Foundland belong to this category, see Table 3. Classification on speckling: Class 1 - yellow iris, 0% > 1% speckling, see iris speckling).

below: Kumlien's Gull (kumlieni) 6th cycle - 7CY, February 15 2022, Julianadorp, the Netherlands. Picture: Mars Muusse.

below: Kumlien's Gull (kumlieni) 5th cycle - 6CY, February 23 2021, Julianadorp, the Netherlands. Picture: Henk Post.

below: Kumlien's Gull (kumlieni) 5th cycle - 6CY, January 24 2021, Julianadorp, the Netherlands. Picture: Mars Muusse.

below: Kumlien's Gull (kumlieni) 5th cycle - 6CY, January 21 2021, Julianadorp, the Netherlands. Picture: Henk Post.

Dave Brown lives in St. John's, Newfoundland and gets tons of gulls each winter in his town. Dave lives at walking distance from Quidi Vidi Lake, no doubt the best location in the world to observe Kumkien's Gulls in all plumages in winter. Dave: "Rarely I see “kumlieni” with obviously pale mantle, and when I say rarely, I mean less than 10 ever. I have never been sure what to make of such birds. Also, I have reviewed large collections of photos from Iceland and often kumlieni there have a mantle shade that matches glaucoides, such birds would easily stand out among Kumlien's flocks in Newfoundland."

He continues: "Another thing that I tend to notice more on glaucoides than kumlieni is this extensive dirty brown, smudgy head streaking. While head streaking on Kumlien's that I see here in Newfoundland is cloudier than say Herring Gull, it often lacks this warm colouration, tending to be more gray and not often does it extend well onto the chest (though it does sometimes)."

And Dave would never regard such a bird in Juliandorp as glaucoides, "Although it does appear somewhat different than the Kumliens that I’m used to. I’ve been trying to document these birds and should find some time to post some photos".

Dave has an excellent BLOG about the birds in Newfoundland.

below: Kumlien's Gull (kumlieni) 4th cycle - 5CY, February 03 2020, Julianadorp, the Netherlands. Picture: Mars Muusse.

Now 5CY bird with brown immature pattern on the wing. Returning bird for the 4th winter.
Over the last years, bird was labeled 'ordinary Iceland Gull', but this winter it has returned with faint subterminal markings, most obvious on P9 but also subterminal markings on P10, P8 & P7. On P9 suggesting some kind of 'ghost mirror'.

In 2020, no certainty whether the pattern would still be visible next year when it will be fully adult, or if these markings would disappear completely leaving all-white primary tips.
Already in 2nd cycle it had a very pale staring eye (February 2018) onwards.

Best thing for Dutch twitchers: "Let's wait another year...", although such obvious markings in 4th cycle, it is highly unlikely to completely dissapear the next season.

below: Kumlien's Gull (kumlieni) 3rd cycle - 4CY, April 05 2019, Julianadorp, the Netherlands. Picture: Henk Post.

Very pale eye.

below: Kumlien's Gull (kumlieni) 3rd cycle - 4CY, March 29 2019, Julianadorp, the Netherlands. Picture: Leon Edelaar.

Outerwebs of P6-P10 with darker patches, which are darker than primary coverts. Still, brown tone on greater coverts obviously darker.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, February 03 2018, Julianadorp, the Netherlands. Picture: Leon Edelaar.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, January 26 2018, Julianadorp, the Netherlands. Picture: Henk Post.

Outerwebs of P5-P9 with darker patches (which are darker than outerwebs of inner primaries), outerweb of P10 very pale. Still, markings on e.g. primary coverts are a shade darker.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, January 20 2018, Julianadorp, the Netherlands. Picture: Henk Post.

Outerwebs of P5-P9 with darker patches, outerweb of P10 very pale.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, January 18 2018, Julianadorp, the Netherlands. Picture: Henk Post.

No real clue this individual will develop into adult kumlieni.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, January 16 2018, Julianadorp, the Netherlands. Picture: Henk Post.

P8-P10 with darker tone outerwebs, still not as dark as e.g. the brown tone in wing-coverts or tertials.

below: Kumlien's Gull (kumlieni) 2nd cycle - 3CY, January 14 2018, Julianadorp, the Netherlands. Picture: Leon Edelaar.

below: Kumlien's Gull (kumlieni) 1st cycle - 2CY, March 30 2017, Julianadorp, the Netherlands. Picture: Henk Post.

Primaries match glaucoides with inner primaries darker than outer primaries. More over, the outerwebs of the outer primaries almost white and the innerwebs of outer primaries buffish.

below: Kumlien's Gull (kumlieni) 1st cycle - 2CY, March 26 2017, Julianadorp, the Netherlands. Picture: Henk Post.

Bird has still not developed an obvious pale bill base by late March (pro kumlieni). In the folded wing, primaries are immaculate white (pro glaucoides), but remember original tone effected by bleaching in late winter. Transversal bars on tertials continue over the full width, also at proximal part (pro glaucoides).

below: Kumlien's Gull (kumlieni) 1st cycle - 2CY, March 20 2017, Julianadorp, the Netherlands. Picture: Henk Post.

Very much an ordinary Iceland Gull glaucoides.

below: Kumlien's Gull (kumlieni) 1st cycle - 2CY, March 17 2017, Julianadorp, the Netherlands. Picture: Henk Post.

Dave Brown, from St. John's, Newfoundland: "I’ve spent considerable time on 1st cycle Kumliens over the last 2-3 years here in Newfoundland. Sometimes it seems the more I look at them the more confusing they get."

To Dave, it seems the main points of difference in 1st cycle birds are:
- bill colour: glaucoides has a much greater tendency to be bi-coloured in fall and early winter particularly.
- tertials: glaucoides had a tendency to have more intricately marked tertials with Kumlien's more often showing larger solid centres. Having said that, it seems fully marked tertials that lack any solid portions are not terribly unusual in 1st cycle Kumlien's.
- tail barring: kumlieni tend to have more solid tail bands on average vs the often completely and intricately barred tails of 1st cycle glaucoides.
- moult timing? Does glaucoides have a tendency to replace 1st cycle scapulars sooner than Kumliens?