Interesting gull on Scilly!

Found this interesting 3rd winter gull at Porth Mellon yesterday morning with 70-80 Herring Gull. 

  If this is a hybrid then what species are involved? It's got a lot of gullers, whose looked at the photos, stumped! Although some believe that's it's just a European Herring gull !!

  I was passing Porth Mellon when I saw Higgo on the side of the road. So I drove past him hoping he wouldn't notice me! He was scanning the gulls on the shore and I decided to join him. He told me that he ain't seen anythin but as I started checking the gulls out I immediately said 'Get on this Higgo!' It was a gull that appeared a tad smaller and paler than Herring Gulls with the jizz of a Kumlien's/Iceland Gull but it had dark tertials and primaries! The bill was greenish and small like that of Kumlien's/Iceland Gull. I said to Higgo that it might be a possible Thayer's Gull! Not that I've ever seen one before. I didn't mess around and quickly alerted others.With in minutes Joe Pender was on the scene followed by Bobby 'Dazzler' Dawson. It had been sat the water for a good twenty minutes before flying off towards nearby sharks Pit where we lost it. As it just flew off, three other local birders arrived, including Ren. We all drove to Porthloo but after another twenty minutes, all of note were the same white-wingers that a few of us saw before I tried to avoid Higgo at Porth Mellon! The 2nd winter and juvenile Iceland Gull and the juvenile Glaucous Gull were showing well in the sunshine. 
  For the rest of the day I spent looking for this damn gull with no success. Instead it was more white-wingers including 3 juvenile Iceland Gull at Morning Point. 

  Later I looked at the photos of the gull on the PC and could see it had pale eyes. Something you couldn't see on the back of the camera. Also, on the net, the nearest I could find to the gull in question was possibly Kumlien's/Thayer's intergrade. I put the photos of the Porth Mellon gull on various FB gull sites and sent them to Martin Elliot, RBA and others. Some birders on the FB pages believed it was just a European Herring Gull! However, RBA were stumped and understandably couldn't put a name to it while Martin Elliot replied with this...

Bloody hell!! That is one weird bird!! Did the pp really look that black in the field?? I reckon you aren't far off the mark!!  Structure, apparently pale uppers, pale eye all bad for Thayer's but good for Kumlien's or Iceland so an intergrade would be possible. However, what I find strange is how pale the uppers look and how dark the outer pp are- they actually look too dark for thayeri!! Kumlien's or Iceland has to be one of the parents- Ice.x Thayers is supposed to be possible in n.w. Greenland! I'd guess kum.x thay would have darker uppers, and still think the pp are too black, but it's hard to see how they could be that dark in Icexthay even if the uppers would be better explained. I also think there is too much black/blackish on p5 and p4, and up the inner edges of p6-out even for a full Thayers, so it should be even less likely when "watered-down" with Kumlien's or Iceland! It hasn't been recorded as far as I know, and shouldn't on normal range, but I can't see why either Ice. or Kum. could't hybridise with Herring in Iceland or smith in the States/Canada!?? it would be a better mix for upperpart shade and the extensive black in pp and tertials!  

                                                                                            

In the field it was noted that it was a tad smaller and paler than the Herring Gulls.

Note the lack of any markings on the upper and under tail coverts

In the photos it's not so obvious in the dull light but in the field the small bill had a greenish hit to it.

In flight the rear end I was surprised to see a broken dark tail band and the lack of any markings on the upper tail. I guess this will never be positively identified. Any comments welcome.

Higgo scaring the Glaucous Gull off

  

All three white-wingers together at Porthloo

This morning while watching 2 juvenile Iceland and a single juvenile Glaucous Gull at the airport, at the same time Joe Pender had 2 Iceland and a Glaucous Gull while Ren Hathway was watching another Glaucous Gull at Porthcressa. I had this 2nd winter at Porthcressa yesterday making it a new arrival!

Also today, the SNOWY OWL was on Tresco Castle Down.

Sunset over St Agnes from the Garrison