As my experience with Iceland Gulls in Denmark was limited the occurrence of numerous white-winged gulls in northwest Europe this winter made a unique opportunity to explore. Adding the possibility of a few Kumlien’s Gulls made it just pure pleasure to have two full weekend days on February 4-5 among the rare gulls in harbours along the West Coast of Jutland.
I managed to take photos of a record number of 27 true white-winged gulls and one Thayer's Gull. The individuals were 19 Kumlien's/Iceland Gull-types, 8 Glaucous Gulls and one
Thayer's Gull. Even though the temperature dropped below -17 degrees C I loved every minute of it.
Kumlien’s Gull was not convincingly recorded in Denmark before this winters invasion so the intension with this post is to provide some overview which can help the Danish Rarities Committee in their future assessment of
kumlieni claims.
The 19 Kumlien's/Iceland Gull-types have been categorised into different groups below and I hope people will comment and help reclassify the different individuals.
Kumlien's Gulls which Rarities Committees should accept:
These individuals have all been identified as Kumlien’s Gulls because they have either subtle dark shading on the outer webs of at least p6-p10; a faint 'ghost mirror' on P10; faint dark shading on p6-p9 reaching the primary tips or sub-terminal bands on the outer primaries.
The dark shading on outer primaries of especially second winter individuals is as least as dark as the shading on primary coverts and the outer primaries are darker or at least not paler than the inner primaries.
#1.1:
3cy, 5.2.2012, Hirtshals Harbour
#1.2:
4cy, 5.2.2012, Hanstholm Harbour
#1.3:
4cy, 5.2.2012, Hanstholm Harbour
#1.4:
4cy, 5.2.2012, Hirtshals Harbour
Individuals which Rarities Committees should not accept as they are currently not without doubt
Identification of these examples is not so straightforward. All of these individuals may be Kumlien’s Gulls, however they are currently considered to be well-marked Iceland Gulls. Most individuals have rather dark peppered eyes, light grey marbling on outer webs of outer primaries, some faint pigmentation along the tip of the outer primaries (sub-terminal bands) and some photos give the impression of a diluted version of a “string of pearls”. However, note that it is not abnormal for 2nd- and, especially, 3rd-cycle
glaucoides to show a brown wash on the outer primaries. The plumage of such well-marked immature gulls often looks quite retarded, with still lots of brown in the wing. Note that the brown wash on outer primaries of such birds simply matches the brown wash on outer secondaries, as is often the case in other 3rd-cycle gulls (e.g. Herring Gull). It is therefore considered just to be a trait of immature plumage.
#2.1:
3cy, 4.2.2012, Hvide Sande Harbour
#2.2:
3cy, 5.2.2012, Hanstholm Harbour
#2.3:
3cy, 5.2.2012, Roshage, Hanstholm
#2.4:
4cy, 4.2.2012, Hvide Sande Harbour
#2.5:
4cy, 4.2.2012, Hvide Sande Harbour
#2.6:
4cy, 5.2.2012, Hirtshals Harbour
#2.7:
5cy, 5.2.2012, Hirtshals Harbour
#2.8:
5cy, 5.2.2012, Hirtshals Harbour
Putative Iceland Gull
These gulls which have all been recorded during the record influx of Kumlien’s Gulls are labeled as putative Iceland Gull instead of calling them definite Iceland Gulls. This line was followed because completely white-winged Kumlien’s Gull is claimed to be indistinguishable from
glaucoides Iceland Gull.
#3.1:
3cy, 4.2.2012, Hvide Sande Harbour
#3.2:
3cy, 5.2.2012, Hanstholm Harbour
#3.3:
3cy, 5.2.2012, Hanstholm Harbour
#3.4:
3cy, 5.2.2012, Hirtshals Harbour
#3.5:
4cy, 4.2.2012, Hvide Sande Harbour
#3.6:
5cy, 4.2.2012, Hvide Sande Harbour
#3.7:
5cy+, 5.2.2012, Hirtshals Harbour
When I look at the excellent work by
Howell and Mactavish (2003). I think one type may be missing. It is the type where the outer webs of the outer primaries are not obviously dark pigmented and approach the type A (stage 0) or somewhere between the type A (stage 0) and type B-C (stage 1) except for the presence of faint subterminal bands near the tip of at least p8-p9. Sometimes there is the impression of a faint “string of pearls” due to the pigmentation on inner primary webs reach further towards the tip than what I find typical for
glaucoides. One could argue that such a primary pattern would fit in right with the type D-F (stage 2) with respect to the subterminal primary band, whereas the colouring of the outer webs would fit in between type Aa (stage 0) and type B-C (stage 1).
Several such individuals have been seen in Denmark this winter and we have trouble to decide what to think of them. Do such individuals ever occur in Newfoundland? Any comments are more than welcome...
References
Howell, S.N.G. & Mactavish, B. 2003.
Identification and variation of winter adult Kumlien's Gulls. Alula 9:2-15.
