Caspian Gulls in Peterborough

I'm back in Lincolnshire for Birdfair weekend and have been able to sneak in a couple of fairly brief sessions at Dogsthorpe Tip over the past two days - one on my way back home yesterday and one before work this morning. In total I've seen five Caspian Gulls: two 3cy and juvenile yesterday and then two of those birds plus a second juvenile and a near-adult (4cy) this morning.

Scope views of the pit are pretty good at present but both yesterday and today have been very warm, with an abundance of heat haze making photography difficult. It's a stretch for my 400mm lens to produce anything decent at the best of times here and so the efforts below are really just for documentation. Unfortunately the near-adult wasn't photographed despite doing a brilliant fly-past at about 30m range - I should have nailed it but my camera was on the wrong settings and so all I have are blurs.

Bird #1: juvenile, 17-18 August

I'm a bit sceptical about whether this is a pure Caspian Gull. Plumage is a little on the dark side - not out of range for a juvenile Casp but, when combined with the fairly Herring-like structure (quite big-headed and short-billed) plus quite heavily marked uppertail and undertail coverts, alarm bells sound. However it possesses the typical mouse-brown basal colour as well as the long, drooping lower tertials of a juvenile Casp and does kind of just look like one - if you don't stare too hard! The underwing is pretty pale, too, if not as pale as it can be in cachinnans. Perhaps it's from Germany.

Bird #2: juvenile, 18 August

Unlike the other youngster, no doubt about this one! First shot is with the DSLR, second with my iPhone 5.

Bird #3: 3cy (2s/3w), 17 August

Structurally quite obvious and also showed a small white mirror on retained p10.

Bird #4: 3cy(?), 17-18 August

I didn't realise this was a different bird to the above until I reviewed images this evening! Present almost next to the other 3cy on 17th, hence the confusion.

At least eight Yellow-legged Gulls were seen over the two sessions with the commonest age class being juveniles (four) followed by 2cy (three) and a single 4cy. Weirdly no adults; traditionally I've found them to be the commonest age class here in past summers.

Juvenile Yellow-legged Gull, 17 August