First off, a very warm welcome to new Birding Frontiers team member, Peter Adriaens. Read his biog and see his remarkable photo at the end of this post 🙂
While our knowledge of birds in general has increased exponentially over the last few decades, it seems that some gull taxa have managed to remain a mystery. This is particularly true for the “Iceland Gull complex”. The taxonomic position of Thayer’s Gull, Kumlien’s Gull and Iceland Gull is a much discussed topic, but for the last 15 years or so, the debate seems to have been going in circles rather than forward. It may even be going backward: indeed, Snell (2002) in ‘Birds of North America online’ treats the three taxa as just one, monotypic species, Larus glaucoides. Thus, we are led to believe that gulls with white wing tips (glaucoides) living in Greenland are the same taxon as gulls with black wing tips (thayeri) living in western North America, 2,000 to 5,000 km further away. Convenient perhaps, but a bit despondent surely?
The debate is characterised by many unanswered questions and a lot of speculation. To add something more informative, I would like to draw attention to the calls of these taxa. For display, large gulls have a “long call” that is unique to each taxon. It is effectively the song of a gull, and consists of three separate stages, the third one being a long, loud series of fairly short, staccato notes. One thing that the three “Iceland Gull taxa” have in common, is that the staccato notes of the long call are delivered more slowly than in other large gulls: there are usually only two staccato notes per second, as opposed to four in, e.g., European or American Herring Gull. For a recording and sonogram of a displaying pair of the latter taxon, have a look at the recording >>>HERE<<< and note that about 3.5 – 4 staccato notes are delivered per second (from seconds 3 to 7), at a frequency of c 1000 to 4000 Hz.
Yet, there are noticeable differences between the three “Iceland Gull taxa” as well. Recordings have become available in recent years, except for Kumlien’s Gull, so I recorded this taxon myself in Newfoundland in January and February 2013. When discussing these recordings with Magnus Robb, it became clear that especially Thayer’s Gull is somewhat different. While gull long calls are variable, e.g. differing between male and female and depending on the kind of interaction that is going on, the difference may be significant, and has actually been hinted at before: Sibley (2000) described the long call of Thayer’s Gull as lower and flatter than (American) Herring Gull, while Iceland Gull is said to be ‘shriller’ (i.e. higher).
So what do these birds sound like? The Macaulay Library has three recordings of adult Thayer’s long calls and two of flight calls. You can listen to them >>> HERE <<< . As the recordist also comments, these calls sound rather deep. If we put this into a sonogram, we can see that the fundamental (i.e. lowest) staccato notes start below 1000 Hz and have a rather flat, gently arched shape. There are also some guttural sounds, which go below 500 Hz.
Note also that the flight calls sound quite low, starting clearly below 500 Hz.
Another recording of Thayer’s Gull long call is available on the Stokes CD ‘Bird songs of West America’. Again, the sonogram shows deep staccato notes (starting below 1000 Hz) with a flat shape.
Compare the Thayer’s Gull calls above to the following recording of a displaying adult Iceland Gull (nominate glaucoides), made by Magnus in Iceland in spring:
Transferring this to a sonogram reveals that the call notes have a distinctly peaked shape, are all clearly above 1000 Hz and therefore higher pitched than in Thayer’s Gull:
Goethe (1986) based on several hundreds of recordings made in breeding colonies in Greenland and on birds in captivity, also describes the long call of adult Iceland Gull as higher than 1000 Hz. He also found it to be 500 to 700 Hz higher than in Herring Gull.
Further recordings of nominate Iceland Gull can be found on commercial CDs such as Schulze’s ‘Bird Songs of Europe, North Africa and the Middle East’ – though the long call on there is that of an immature bird.
Flight calls can be heard from about the 24th second in Magnus’ recording (first recording above and in short section extracted in 2nd recording directly above). These sound higher pitched than in Thayer’s Gull. In the sonogram, they are clearly above 1000 Hz:
The long call of Kumlien’s Gull seems similar to Iceland Gull, though perhaps sounding even higher – which is a bit unexpected in a taxon that is seen as intermediate between Thayer’s and Iceland Gull, or even as a hybrid between the two by some. In any case, the long call is clearly higher than in Thayer’s Gull, with the fundamentals starting above 1000 Hz. The flight calls sound higher pitched too; in the sonogram, they are at about 1000 Hz or higher, while Thayer’s flight calls start below 500 Hz already.
Kumlien’s Gull adult Long calls (best 2) Newfoundland Jan- Feb 2013. Peter Adriaens
Kumlien’s Gull adult Long calls (best) Newfoundland Jan- Feb 2013. Peter Adriaens
Kumlien’s Gull adult Long calls (best 3) Newfoundland Jan- Feb 2013. Peter Adriaens
Kumlien’s Gull adult Long calls and Flight calls Newfoundland Jan- Feb 2013. Peter Adriaens
Kumlien’s Gull adult Flight calls Newfoundland Jan- Feb 2013. Peter Adriaens
It seems interesting that Thayer’s Gull appears to have a deeper, flatter voice than Iceland, Kumlien’s and even Herring Gulls. While I fully realise that many more recordings are needed, especially from the breeding grounds, I simply hope that the above information provides a fresh look at an old problem. Perhaps the taxonomic debate cannot be settled by measuring skins in musea. There is still a need for more detailed and controlled research, which should probably also take into account voice and ecology. Thayer’s, Kumlien’s and Iceland Gull certainly behave like three distinct populations; each one has its own breeding and wintering range, for instance. Each one seems to have its own plumage traits (Howell & Elliott, 2001; Howell & Mactavish, 2003) and probably also voice. If the whole Iceland Gull complex is just one big cline, as suggested by e.g. Snell (2002), how can there be three distinct populations? And if Kumlien’s Gull is merely a hybrid, as advocated by e.g. Weir et al (2000), why does it have its own range? Surely the taxonomic debate can only be settled when there are firm answers to such questions.
Goethe, F. 1986. Zur Biologie, insbesondere Ethographie der Polarmöwe (Larus glaucoides Meyer, 1822). Ann. Naturhist. Mus. Wien. 88/89(Ser. B):113-146.
Howell, S & Elliott, M T. 2001. Identification and variation of winter adult thayer’s gulls – with comments on taxonomy. Alula 7 (4): 130-144
Howell, S & Mactavish, B. 2003. Identification and variation of winter adult Kumlien’s Gulls. Alula 1: 2-15
Snell, R. R. 2002. Iceland Gull (Larus glaucoides), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/spe…0.2173/bna.699
Weir, D. N., Kitchener A.C., and McGowan R. Y. 2000. Hybridization and changes in the distribution of Iceland gulls (Larus glaucoides/kumlieni/thayeri). J. Zool., London, 252: 517-530
Trickier birds would be very interesting to record…
“As usual, I am fashionably late – even when it comes to joining something as interesting and thought-provoking as the Birdingfrontiers.com website. I am honoured to now be part of a great team of blog writers, and I hope I can contribute something useful from time to time. I promise it will not always be about gulls! As an editor for Dutch Birding, I enjoy writing identification papers, but some topics and ideas probably lend themselves better to the blogging world than to a 25 page in-depth article. I live in Belgium, where I have had the good fortune to be able to work in gull and tern colonies for a few years. I have also worked in Armenia, surveying breeding birds and migration. I have traveled widely, mainly with the idea of becoming more familiar with some species that interest me. Birding has been my main passion for over 25 years and I still thoroughly enjoy it – be it when seeing a new bird or some kind of variation that I was not familiar with; it is all thrilling. If nothing else, it is often great to just be outdoors. Time spent in nature is never time wasted, as they say…”
(Photo taken just before entering a heavily polluted part of the Maasvlakte when we were ringing Common Terns…)
Peter Adriaens, December 2013