A gull which doesn’t quite fit the bill

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.

Second calendar year gull, Ravensthorpe Res, 16th August 2019 (Gary Pullan)

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.

Second calendar year gull, Ravensthorpe Res, 19th August 2019 (John Moon)

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!

Putative Azorean Gull at Stanwick

There are two accepted British records of Azorean Gull, the atlantis race of Yellow-legged Gull, based upon two individuals, one of which was a well-travelled bird that visited Northamptonshire in 2013, 2014 and 2015. Is this another, or the same returning individual in a different guise?

On Wednesday, 4th October, Steve Fisher found and photographed a good candidate for an Azorean Gull at Stanwick Gravel Pits. It appears to be the same bird which he also saw there briefly on both 8th and 15th September. Steve’s images, below, pretty much capture all the visible features, so, is it one?

Putative Azorean Gull, Stanwick GP, 4th October 2017 (Steve Fisher)

Head and mantle
This bird does not have a full winter hood and so doesn’t immediately resemble the returning adult from 2013, 2014 and 2015, accepted as the second British record by BBRC. It has been said that the extent of the winter head streaking can vary from year to year in the same individual but this remains to be proven – unless anyone knows otherwise. In any case, the returning individual over those three years appears to have exhibited consistency in the extent of its head streaking, always giving the bird a strikingly hooded appearance. Additionally, the mantle of that bird appeared darker than that of this autumn’s individual, although light conditions, camera settings and processing can, of course, serve to distort the true colour. Having said that, in comparison with the Yellow-legged Gull in the image below, there appears to be little difference in mantle colour. Extent of winter hood varies considerably in Azorean Gull – see here, for example and the bird is not too dissimilar to one, also thought possibly to be Azorean Gull, which visited Shawell in Leicestershire in September 2012.

Putative Azorean Gull, Stanwick GP, 4th October 2017 (Steve Fisher)

Wing pattern
The upper and lower wing patterns are interesting and look like they could fall within range of variation for Azorean Gull. There is a single mirror on P10, separated from the small white tip by a narrow black band and no mirror on P9, where Yellow-legged Gull usually has a small mirror. P5 shows a black subterminal band. The underwing shows darkish grey secondaries and primary bases contrasting with white coverts – perhaps not as dark as may be expected for Azorean Gull. Questions: is the mirror on the upper side of P10 too extensive for Azorean Gull? It looks OK on the underside. Is the subterminal black band on P5 too broad for Azorean Gull?

Putative Azorean Gull, Stanwick GP, 4th October 2017 (Steve Fisher)
Putative Azorean Gull, Stanwick GP, 4th October 2017 (Steve Fisher)

According to literature (specifically Olsen & Larsson – Gulls of Europe, Asia and North America), Azorean Gull moults earlier than Yellow-legged, which fits with the Stanwick bird which is still growing P10 but everything else, including secondaries and tail, appears to have been completed. Yellow-legged might be expected to still show more signs of moult at this time of the year (but not always).

For reasons stated above, it is clear this is not the same individual as has already occurred here in previous years. So, a very interesting bird, then. 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.

It soon settled down and spent the next two days in the vicinity of the dam, occasionally flying off north but habitually returning again after only short periods of absence. It is still present today (15th September).

First recorded as recently as 1987, it’s a major rarity in Northants with only ten previous records, in 1987 (5), 1993, 1997, 2007, 2008 and 2010, all of which have been in September or October.

Juvenile Sabine’s Gull, Daventry CP, 14th September 2017 (Alan Coles)
Juvenile Sabine’s Gull, Daventry CP, 14th September 2017 (Alan Coles)
Juvenile Sabine’s Gull, Daventry CP, 14th September 2017 (Alan Coles)
Juvenile Sabine’s Gull, Daventry CP, 14th September 2017 (Alan Coles)

Mediterranean Gull – a new breeding species for Northants

A new species is added to the list of birds breeding in Northamptonshire as Mediterranean Gulls nest for the first time at Stanwick Gravel Pits
Mediterranean Gulls, Stanwick GP, 6th May 2017 (Bob Bullock)

Mediterranean Gulls have been appearing with increasing frequency among Black-headed Gulls breeding in the Nene Valley – particularly within the well-established Summer Leys colony. This appears to be a recent phenomenon, principally involving single birds which are apparently not sexually mature. Most remain for only a short time during spring but in 2015, a second-summer was discovered in the Summer Leys colony on 18th March, remaining there until 29th June. During this period, it established and held territory, continually displaying to the local Black-headed Gulls. This was repeated in 2016, with another second-summer visiting the colony for only a short duration on 20th-21st March. However, two adults appeared there little more than five weeks later, on 28th April, before relocating the following day to the Stanwick colony, where they were seen again on 11th-12th May. There were no subsequent sightings.

Fast forward to this year, 2017 and 5th April, when a pair was displaying among the Black-headed Gulls at Stanwick, after which they promptly disappeared. On 24th April two were again present – both wore BTO rings and one sported a black leg tag ‘SA30’, which has not yet been traced to source. Again, they were not subsequently reported but then two – amazingly a different pair – arrived in the Black-headed Gull colony on Rotary Island at Summer Leys LNR on 3rd May. Appearing settled, they remained difficult to observe in the island’s vegetation until 5th May.

The following day, 6th May, what was assumed to be the same pair appeared in Stanwick’s Black-headed Gull colony, where they were observed copulating and defending territory.

Mediterranean Gulls, Stanwick GP, 6th May 2017 (Bob Bullock)
Mediterranean Gulls, Stanwick GP, 6th May 2017 (Bob Bullock)

Nest construction ensued and eggs were laid, subsequently hatching, with the young visible within the colony. It was after this that fortune took a turn for the worse. During the first week in June the young had disappeared – assumed to have been predated by the local Lesser Black-backed Gulls – and by the end of the week both adults had also abandoned the site. Not a positive outcome for a first breeding attempt but, as this species continues to increase in the UK and indeed breeds in Cambridgeshire, we can surely look forward to further attempts in the future.

Thanks to Steve Fisher for providing information and to Bob Bullock for images.

Behind DIRFT 3

Where Birding meets Logistics

If you have a sense of adventure, a pioneering spirit and you are willing to risk being hit by an HGV, while getting covered in mud, then read on …

The busy A5, just north of Crick, may not at first sight seem an ideal birding location but there’s more to it than meets the eye. Sandwiched between this major road and the M1 is a 250-hectare wedge of land currently under development by Prologis as an extension to the long-established Daventry International Rail Freight Terminal.

DIRFT 3 represents the third phase in this continually expanding logistics complex, which already includes national distribution centres for Tesco, Sainsbury’s and Royal Mail, as well as those of a number of other well-known retailers and third party logistics operators. The project is a joint venture between Prologis and Rugby Radio Station Limited Partnership, with construction taking place on the former Rugby radio station site, the masts of which have now been removed. 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 (WTBCN). Based on the creation of new meanders to the Clifton Brook tributary – a watercourse running east to west across Lilbourne Meadows – a varied wetland habitat will include wet woodland and reed beds, pools and scrapes. The reserve will be located below Lilbourne and behind the industrial site’s northern perimeter landscaping. This new habitat is designed to attract a range of wetland birds and two bird hides are also included in the plan. Excellent!

But back to the here and now. Levelling of the site is well under way and, as a spin-off, some sizeable shallow lagoons and pools have been inadvertently created as a result of standing rain water on the recently created flat earth surfaces. While some of these are inaccessible, deep within the construction site, one area in particular is readily viewable from the A5 – if you don’t mind the proximity of thundering traffic! Parking is also a problem but possible with care in the limited number of narrow pull-ins and lay-bys. 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.

Caspian and Yellow-legged Gulls, DIRFT 3, 12th March 2017 (Gary Pullan)

Having stumbled across it by accident while driving along the A5, I have visited this site a good number of times over the last month, recognising its potential for gulls in particular, and I’ve been lucky (or persistent) enough to find Glaucous and Caspian Gulls there. Its location is prime for receiving gulls, which roost at nearby Draycote Water (Warwickshire) 13 km to the south-west and feed on Shawell Landfill (Leicestershire) 5 km to the north and it seems logical to assume there is movement between all three sites. I’m hoping the new Lilbourne Meadows LNR will continue to attract them long after DIRFT 3 is completed. 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!

A particularly tricky white-winged gull: revisited

Revisited, reassessed and … right first time!

glaucAfter 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 white-winged 4th winter gull at Rushton last weekend as an Iceland Gull.

Mick Ketley kindly contacted me with a solid argument which supports my initial identification as a Glaucous Gull. Here’s what he says:

As you can imagine, I found your account of great interest and of a very similar situation to what we had at Eye Brook Reservoir (EBR) last month, Saturday 7 January. I thought it strange that you changed your mind when it was put out on recent reports. I feel strongly that you were correct in the first place, that it is a 4th w Glaucous Gull albeit a female, considering its size and bill. Your photos show clearly the following features.
TOP PHOTO: It appears MASSIVE compared to the Common Gull (at its primary tips). It is MUCH LARGER than the adult and juvenile Lesser Black-backed Gulls. Is MUCH LARGER than the 1st w Herring Gull (beside the Common Gull) and ‘argenteus’ Herring Gulls at the top of the photo. It appears to closely approach the size of the large Herring Gull (left of centre at the top of the photo). Taking these pro-Glaucous features and size of bill into consideration it seems to be a female Glaucous Gull.
SECOND PHOTO: Similar comparisons.
THIRD PHOTO: Self-explanatory, HUGE beside the Lesser Black-backed Gull.
BOTTOM PHOTO: On its own. I would expect the primary projection to be slightly longer on an Iceland Gull. The position of the eye is up nearer to the forehead, the ratio of eye diameter to bill length is well within 1:5 to 1:7. These are certainly pro-Glaucous features. Some Glaucous Gulls can show a primary projection, while others, especially bolt upright, have a ‘very blunt rear end’.
To date my personal tally of local (i.e. EBR and around the Corby area) Glaucous Gulls is 36 individuals and 49 individual Iceland Gulls. I found a personal guide to sexing Iceland Gulls as follows, although they have a different structure, I found BODY MASS to be helpful, in comparison with large male Common Gull, = female Iceland. And with Lesser Black-backed Gull = male Iceland.
This is not the first time nor the last this situation arises re. white-winged gulls, I’ve known a few. On Saturday 7 January, last month, I spent a lot of time at Rushton a.m. as there were three large concentrations of gulls, nothing special. Then I went to RW and arrived at EBR at 3.00 p.m. just as Andy Mackay, Colin Towe and Chris Lythall located a white-winged gull on the water at the inflow. On its own just like your bird, we all agreed to Iceland Gull, small, extremely pale grey mantle and upper wings (pro-Iceland), low profile and long attenuated rear end, even the ‘small’ bill size. However I did remark that the eye was up nearer the forehead. Then other gulls swam alongside it and alarm bells rang. Even ‘argenteus’ were dwarfed by it and it was matching larger Herring Gulls. If you go onto LROS latest sightings, scroll to the 2 photos dated 7 January, it looks like an Iceland Gull (adult), touch on the photos for the bigger picture, no pun intended, and like yours, seems to be a female Glaucous Gull, compared to other gulls with it. The shade of grey appears darker in the photos, it was extremely pale.

I cannot disagree with Mick. Further research throws up the not infrequent occurrence of Glaucous Gulls with ‘long wings’ and, despite the apparently small bill, this gull retains that mean, Glaucous look …

A particularly tricky white-winged gull

This morning I paid my usual weekly visit to Rushton Landfill. In recent weeks it has been pulling in up to 4,000 gulls, including several Caspians, and the chances of finding either Glaucous or Iceland has been on the cards for some time, given the current higher than usual numbers of both species present in the UK this winter.

Gulls frequently loaf in good numbers on adjacent fields and one of the favourite gathering places is the field immediately north of the landfill, at Storefield Lodge Farm. It was here that, going through the assembled flock this morning, I picked out a first-winter Caspian and, at last, found a white-winged gull.dscn3449-copy My immediate reaction was forth-winter dscn3451-copydscn3452-copyGlaucous 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.

Next to Lesser Black-backed and Herring it appeared marginally larger, although the bill was not long but the head appeared rather flat-crowned. Given size and proportions I quickly came to the conclusion it must be a small female Glaucous. Over the next couple of minutes I took a few long distance digiscope shots before the bird disengaged itself from the flock and flew a few metres closer. Any potential prolonged observation was quickly cut short at this point, however, as the explosive gull-scarer went off on the adjacent landfill and all the gulls took to the air and quickly dispersed. Despite a search of neighbouring fields I failed to relocate the gull. dscn3455-copyIt 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.

It’s official: Azorean Gull now on the Northamptonshire List

Azorean Gull, Azorean Yellow-legged Gull, Azores Gull – call it what you like but, following its acceptance by the BOU on to the British List earlier this year, Larus michahellis atlantis – currently considered to be a distinctive taxon – is now on the Northamptonshire List based on the acceptance by British Birds Rarities Committee of a returning adult to Stanwick GP during 2013, 2014 and 2015. The accepted records are as follows:

2013 27th September intermittently to 6th November (M. T. Elliott, S. P. Fisher)                                        2014 21st October (M. R. Alibone, S. P. Fisher, R. D. Webster)                                                                                        2015 10th October (S. P. Fisher)

Adult Azorean Gull, Stanwick GP, 27th September 2013 (Martin Elliott)
Adult Azorean Gull, Stanwick GP, 27th September 2013 (Martin Elliott)
Adult'Azorean Gull, Stanwick GP, 21st October 2014 (Mike Alibone)
Adult Azorean Gull, Stanwick GP, 21st October 2014 (Mike Alibone)
Adult Azorean Gull, Stanwick GP, 10th October 2015 (Steve Fisher)
Adult Azorean Gull, Stanwick GP, 10th October 2015 (Steve Fisher)

This individual is considered to be (and is treated as) the same returning bird which has been seen in various Midlands counties annually during autumn since its initial discovery in Oxfordshire in 2009. As such it constitutes only the second British Record. This autumn it appears to have again returned, being seen at Stanwick GP and at Grafham Water in Cambridgeshire. For a recap on the accepted Northants occurrences see: 2013  2014  2015

Stanwick Caspian Gull does Dunge!

Remember this juvenile Caspian Gull at Stanwick in September? Steve Fisher, the observer, has just had the news back on its origin.

Polish-ringed juvenile Caspian Gull in moult to first-winter, Stanwick GP, 10th September 2015 (Steve Fisher)
Polish-ringed juvenile Caspian Gull in moult to first-winter, Stanwick GP, 10th September 2015 (Steve Fisher)

20150910_151423Its 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!