The Lincolnshire Bird Club

After having a second and closer look at GPC's mystery gull in the discussion forum I will make a few comments here as the discussion birds message is limited to a few words. I don’t agree with Trevors comment that it is too dark for a Caspian gull and must be some kind of Herring gull. Well at present according to the BOU Caspian gull is some kind of herring gull. Furthermore I don’t think it is too dark for a Caspian gull as at present if we follow Gulls (Klaus Malling Olsen) Caspian gull includes at least 3 subspecies one of which (barbensis) has a relatively dark mantle colour, similar to that of a yellow-legged gull and much darker than a argenteus herring gull. Darker than the bird in GPC's pic.

That said Paul may well be right about the ID of the gull, it could well be a herring gull (argentatus most likely due to quite dark mantle). There are a few other point besides the leg length that don't seem right for Caspian. 1. The bill is a bit bright, the majority of birds I see of this age (and winter adults) have a definite greenish tinge to the bill. 2. The Gonys is a bit pronounced, although its not that easy to judge from the pic. 3. At this age most birds I see have a neck shawl consisting of a few streaks around the back of the neck.

However, in my opinion it does have the general look of a Caspian, this no doubt prompted GPC to take some pics. Especially the fact that the head shape is quite pear-shaped, the eye appears very small and is placed quite far forward and high in the head. All good Caspian pointers.

I have done quite a lot of gull watching over the years and especially while watching large gulls there is always, lets say 1 in 2 or 300 hundred that seems to have mixed characters (Paul’s minefield). I'm sure we have all see these types of gulls, sometimes small dark adult herring gulls with dark eyes and bright bills or almost any combination of un-matching characters. My policy is ignore them and move on to the next bird, as it wont be more than 10 minutes before you see something good you can identify, or yet another unidentifiable herring gull type. I have actually seen a few gulls similar to GPC out in the field and some I suppose my be hybrids and some may just be gulls that by chance resemble Caspian’s. One could argue why does GPCs bird look so much like a Caspian if it doesn't contain Caspian genes.

Hybridization is also a good possibility for any non-conformers, a ringed bird seen in Cambs a couple of winters ago turned out to originate from an argentatus colony. This bird is presumably a hybrid. You will need to scroll well down in the link below to see this bird.

http://cambsbirdclub.blogspot.com/searc ... results=50

If there are any real experts who can identify everything I have dozens of pics of gulls I cant identify, I even have a pic of a gull which I cant tell whether its a black-headed gull, a common gull, or a hybrid of the two!

Pity its not in North or east asia, then it could be a Vega Gull

Kev,

I was merely remarking that it doesn't fit the colouration of what we refer to as Caspian gulls in the UK ( Cachinnans ), As you say it has got a whole host of features that point away from Cachinnans , true that Barabensis is still part of this complex but wouldn't they show yellow legs at this age ?
Gulls really are a minefield at any age with so much hybridization !
As you say the more gulls you look at the more you see that don't appear to fit a particular species.

Trev

My view is that it doesn't really fit anything so, as Kev suggests, move onto something else.