A closer look at the Ravensthorpe ‘Caspian’ Gull
Generally regarded as a Caspian Gull, this second-calendar year (first-summer) bird has been visiting Ravensthorpe Reservoir since early August. From the initial images obtained by Gary Pullan, it looked marvelously ‘snouty’ and long-legged – two features widely associated with Caspian Gull.
There were, however, some characteristics which simply did not ring right for Caspian Gull, leading Gary and I to debate its identity, which swung from Caspian to Yellow-legged, though Caspian x Yellow-legged hybrid and then back to Caspian. John Moon chipped in with a better image, which did not really change anything at the time.
On 31st August, I managed to get some digiscoped shots (below) of which some, after scrutiny, were perhaps more suggestive of Yellow-legged Gull – not least because of the bill structure.
Summary of features based primarily on images taken on 31st August.
- Large and lanky and legs long and good for Caspian
- Shortish (closed) wings but renewed primaries probably still growing
- Mantle shade of grey too light for Yellow-leggedGul but OK for Caspian (but see comments)
- Bill long but heavy, with large gonys – looks in some images to be fine for Yellow-legged Gull but too chunky for Caspian but in others ok(ish) for Caspian
- Underwing coverts quite dark – darker than I would expect for Caspian but Malling Olsen states some Caspians can have quite dark underwings (and see comments below)
- Head shape, long forehead and eye position ok for Caspian and looks ‘snouty’
I forwarded a set of images to Carl Baggott – the Leicestershire Recorder, ‘King of Shawell’ and a man with a true passion for gulls and with extensive experience of Caspian and Yellow-legged Gulls in eastern Europe and Yellow-legged in Portugal.
Carl kindly commented as follows:
This is quite a difficult bird, but I don’t get a Caspian Gull feel from the images. It seems closer to YLG and I am not too concerned about the lightness of the grey feathers as this is quite variable at that age. The tertials favour YLG also, as does the large head and bill. The snouty description of Caspian Gull head is overstressed and doesn’t really help with most gulls. As you say some Caspian Gulls can have dark underwings and I have photographed birds in Germany with similar underwings. Most 2CY Caspian Gulls have pale inner primaries or a venetian blind effect across the inner primaries.
I have seen birds like this at Shawell and left them unidentified. It can be very difficult with ones like this as you don’t know their origin. I have seen Yellow-legged Gulls in Portugal that are easily confused with Caspian Gulls and even American Herring Gulls.
On the question of the possibility of a hybrid:
It could well be [a hybrid], but difficult to say for certain. There is nothing to really hang your hat on. A colour-ring is always useful as you know so at least you know where it’s from. Hybrids are easier as adults or first-winters usually as you can look at coverts (Caspian Gulls especially) on the young birds and primaries on adults. Then it comes down to matter of opinion unless you know the species of the parents. Hybrid is always the go to, but there is a great deal of variation in pure birds.
The above not only highlights the difficulty of identifying ‘odd’ gulls in the field but also the problems with trying to identify them from images taken from different angles and in different poses – for example, see the apparent change in head shape and bill thickness in the above images.
For a set of images of similarly-aged Yellow-legged and Caspian Gulls in The Netherlands see here.
Comments welcomed!
Wednesday 13th September. In the wake of Storm Aileen it was difficult to believe no displaced seabirds would have occurred in Northants. On cue, then, a juvenile Sabine’s Gull arrived at Daventry Country Park at 16.30 and was picked up straight away by Gary Pullan as it circled the northern end of the reservoir.
I am not a big fan of industrial or housing developments on virgin territory but in this instance, given the location alongside existing industry, it doesn’t strike me as being a big deal and the creation of a 70-hectare nature reserve included as part of the development plan is welcome news, going some way to mitigate the loss of green land to industry. Lilbourne Meadows LNR is a collaborative initiative between Natural England, the Environment Agency and the Bedfordshire, Cambridgeshire and Northamptonshire Wildlife Trust (
This one shallow, though extensive, pool is located immediately to the right (south) one of the entrances to the site, about 1.5 km to the north of the Sainsbury’s DC roundabout. The grassy fields to the north of the entrance are also worth viewing. This roadside area holds hordes of roosting gulls – particularly at the weekend when construction activity is minimal – and many drop in to bathe. Over the past two weeks, it has produced Shelduck, Golden Plover, Curlew, Dunlin, Caspian Gull, Yellow-legged Gull and Glaucous Gull and, with spring passage now under way, who knows what else might drop in over the coming weeks.
As far as both the reserve and the industrial site are concerned there is, as yet, no completion date. The area remains in a constant state of flux and will continue to do so for the foreseeable future. Watch this space!
After convincing myself to go against my gut feel and better judgement, it would appear I was wrong in my post-observation photo-based identification assessment of the 
My immediate reaction was forth-winter 
Glaucous as it seemed quite large, looked a little dingy and had a blackish subterminal band on the bill – otherwise it was a winter ‘adult’ with fairly well-marked head streaking, which extended to the neck and upper breast, albeit rather faded. I duly broadcast the news and then went back to getting a proper look.
It was only after later examination of the images I managed to obtain that nagging doubts about the bird’s identity crept in. Although in the first three images reproduced here the bird appears large and ‘mean-looking’ (= Glaucous) in the last of the series of images the true proportions are visible. It lacks the truly hefty proportions of Glaucous Gull, appears attenuated with a long primary projection and has a more rounded head and relatively small, short bill, bearing a resemblance to a Common Gull. This all adds up to it being an Iceland Gull with the size and sometimes flattish, sloping forehead suggesting a ‘butch’ male.
Gull ID masterclass. Don’t miss it …
Its red ring, numbered 85P5, indicates it was ringed as a nestling in a Caspian Gull colony at ZB.KOZIELNO, PACZKÓW, OPOLSKIE, POLAND on 21st May this year by Jacek Betleja and Jakub Szymczak – a distance of 1230 km east-south-east from Stanwick. Even more interestingly, we know it’s still in the UK. It was seen only yesterday by Rich Bonser at Dungeness!
Northants birds 