Saturday, 14 January 2012


Photo 1. The adult culprit, Corvo, October 2011
You may remember back in late October I posted about a ‘Herring Gull’ that I saw on Corvo. Expert commentary on this came from Peter Adriaens, co-author of the seminal paper on adults in a European context (pdf of it here) – and he was helpful and honest as ever.
Peter concluded that there was nothing wrong for it being an American Herring Gull, but the lack of a Casp-like long pale tongue on P10 immediately reduced the chances of reliable identification. 69% of Newfoundland birds ('northern' American Herring Gulls, NAHGs) showed this feature in the sample that his article is based on. Pro AHG features included the all black outer edge to P10 (not broken by the white mirror) and the thin black W pattern on P5; as well as some bayoneting.
Photo 2. Note the leading edge of the wing is black, not broken by the P10 mirror and there is no mirror on P9. 90% of SAHGs show no mirror in P9 just like this. Keep reading...
I bloody said it at the time to Arthur when we saw the bird ‘I bet this is an American Herring Gull, it feels like one, looks like one but reckon it’s not one of those classics so we’ll never 100% clinch it’. And so I was right. This was not a pale-tongued NAHG that you could do for sure.
Photo 3. Still looks a real brute alongside this 1cy atlantis Yellow-legged Gull
So, I kind of left it at that, relatively happy that I’d remain unhappy with the predicament of being closer than close but never a cigar. Roll on December 2011 and a Canadian trip. Here I met up with some local gullers, and this is where my eyes really started to open. These guys watch AHGs all the time, know them inside out - better than us Europeans claiming expert status on sporadic trips/internet birding - and just like we make calls on argentatus and argenteus, it’s possible to make judgements on SAHGs (Great Lake birds) and NAHGs in the field. Interesting stuff.
Photo 4. adult SAHG, Toronto, December 2011; a classic individual, if not with a sightly larger than average white mirror in P10 that extends onto the leading edge of wing. Look at underside of P10 where the black extends way down the primary shaft, with no inkling of that casp-like pale tongue.

Photo 5. Compare the upperside of this bird's left wing (P5 to P10) with that of photo 2. Looks pretty bang on to me.
Kevin McLaughlin has really helped me out and I’ll be eternally grateful for this. SAHGs normally either show a wing pattern of a variable mirror on P10 (sometimes breaching the outer web) OR occasionally a mirror on P10 and a smaller mirror on P9, and a nice subterminal band on P5. The SAHGs in Toronto/Niagara also tallied with what Adriaens and Mactavish said about these birds compared to the Newfoundland NAHGs – ‘shorter grey tongues to P8-10, often no white mirror on P9 (in 90% of those examined), usually a complete black band on p5, and some black on p4 in quite a few birds. All birds had an uninterrupted black band between the white mirror and tip of P10.’
Photo 6. The exception rather than the norm - a SAHG with mirrors on P9 and P10, the latter extending across both webs.
Photo 7. An example of a SAHG with a black marking in P4; it seems as though this bird has dropped P6
Adriaens and Mactavish went on to say that SAHGs appeared smaller, with shorter legs, less sturdy bills, and more rounded heads than Newfoundland birds. So, what with these SAHGs not showing a pale square-ended tongue to the underside of P10 like your classic NAHGs, in a European context you’re more or less f*cked to be able to pick these boys out than brutish NAHGs?
Photo 8. Short-legged and variable head streaking. What I did find was that SAHGs leg colour was consistently bubblegum pink unlike the variability we see in European birds. Compare to photos 1 and 3.
I’ll come to that in a few days... or has a SAHG already occurred in Europe? It's certainly a less than classic NAHG. Have a look here and: -
Photo 9. The regular Nimmo's AHG. Any chance this bird would have passed the test if it hadn't been tracked? I'm currently looking for some underwing shots in flight, so if you have any please email me.

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