Caspian Gull movements around Britain

Andrew Tweed, Josh Jones and Mark Golley

The movements of a first year Caspian Gull could be followed from SSE Poland nr. the Czech border, to Norfolk and then to Essex through autumn 2013 into early 2014, with a ‘bruva from another muvva’  (birds ringed same colony, same day) found in Peterborough in late December ’13

Thanks to keen gull watchers, readers of rings and the power of social media, we joined up some dots. Andrew Tweed kicks off with this ringed Caspian Gull at Rainham, Essex on 17th January:


Great gulling session at Rainham today with 6 Caspians. 2 x 1st win , 2 x 2 nd win , 1 x third winter and an adult. Best tally for a couple of seasons. One of the 1st winters had a yellow ring on its right leg with PNEL written on it. I have had green polish ringed birds before but not yellow. 

Any ideas?  Kind regards, Andy Tweed 

Andy’s request for info was ‘tweeted’ out through Birdingfrontiers. Within a matter of hours loads of clear data emerged. Thanks especially to Josh Jones, Mark Golley. Click:

>>>Movements of yellow PNEL from Polish Caspian Gull Colony<<<

Caspian Gull, Pat's Pool, Cley, Norfolk, November 2013 (Steve Gantlett).Here’s the boy! Only this photo was taken by Steve Gantlett at Cley, Norfolk in late October 2013. Mark Golley explains:

Thanks Martin ~ second one of mine in recent years that’s gone from Norfolk to Essex (one went to Pitsea where Steve Arlow saw it). Herring Gulls too of course, but nothing as as funky as a  Caspian….Emoji

I do love these UK movements. I just knew PNEL would be picked up somewhere else this winter, but wondered if it may go inland to Milton or the Midlands. Essex was the obvious choice tho’ and I’m glad someone has picked him (it’s a beast) up again.

Nice too as it consolidates what we kind of know here about these Norfolk – London/London – Norfolk gull movements.
Bit of background:~ I found PNEL on the evening of October 21st then it was back on October 28th and was seen, almost every night to at least November 9th.

You’ll have seen from the ringing data that you passed on to me where and when it was ringed ~ interestingly this is the second cachinnans from the same Polish colony to make it to Cley ~ I found one here in July 2012 which has subsequently appeared in the Netherlands and Northumberland.

The natal site is in the far SSE of Poland, not that far from the Czech border, due south of Wroclaw.

PNEL was the first in a remarkable (for Cley) run of new 1w cachinnans last autumn. I logged (and photographed) nine different 1w’s between 21st October and 12th November (eight of them between 21st-31st!) ~ an unprecendented run of birds here. There was at least one other 1w that I didn’t see that I was sent shots of….incredibly exciting!


caspian andrew tweedHere’s the same fella at Rainham on 17th January. Photo by Andrew Tweed.

Josh Jones helpfully fills out he picture a little more:

Hi Martin

Find the enclosed the details for yellow-ringed ‘PNDZ’ that I saw in Peterborough on 24th and 27th December 2013.

>>>Movements of yellow PNDZ from Polish Caspian Gull Colony<<<

I’m certain that Andy Tweed’s bird will be from the same ringing scheme in Poland. In fact, ‘PNEL’ sounds like it will be very close in line, so it wouldn’t surprise me if it’s from the same colony as mine, and perhaps even ringed on the same day!

Andy can submit his sighting of PNEL here at – they usually only take a couple of working days to respond.

Just an interesting bit of background, by the way. You’ll see species is not labelled Caspian Gull, but ‘Caspian Gull colony’. This is because the colonies (usually islands in the middle of gravel pits) are generally characterized by dense vegetation and long grass. When they head over to ring them, the adults naturally get up and fly around, leaving the chicks wandering around on the deck on their own. Now, the dominant species in these colonies is Caspian Gull, though a small proportion of birds with mixed characters do occur (per Rich Bonser, who visited one of these colonies last June) as presumably does the odd pair of Yellow-legged Gull. As such, they cannot say for certain that each chick ringed is a pure Caspian Gull, hence the use of ‘Caspian Gull colony’. I think the official word on these ringed birds is as follows:

“Chicks ringed in mixed colonies where Larus cachinnans is the dominant species (it is most likely that these chicks are cachinnans, but other species and hybrids are not excluded); this is the most common code, because most colour-ringed birds are from southern Poland, where this species is the dominant one.”

So, all in all, really very interesting. Basically, it seems that the vast majority of these ringed birds are going to be Caspian Gulls from southern Poland, but there is of course the small chance of a ringed bird being a hybrid (presumably with Yellow-legged Gull).
Also these yellow (and green) ringed birds are seen with reasonable regularity. Here’s a second-winter that Rich Bonser and Steve Arlow had at Pitsea that has now been seen in seven countries(!):

>>> Caspian Gull visits 7 countries<<<

Not overly surprising revelations, but it adds further weight to the belief that the majority of British Caspian Gull records must originate from these Polish colonies.




2 thoughts on “Caspian Gull movements around Britain

  1. Kris Gillam

    great post! This is a subject that I’m keen to learn more about….

    Early December last year I found a Polish ringed Caspian Gull in Newhaven, East Sussex. It was during a time when there was a local influx of gulls which I assumed originated from the east. A short while later the bird was seen again, but it had moved BACK EAST along the coast, to Rye. This was not was I was expecting. However, looking at emerging patterns of gull movements in the local area in the past few winters this may well fit in with what Caspo’s are doing.

    Every year East Sussex experiences a ‘Caspo run’ in December. The first birds start to appear in late Nov/early Dec, peak in mid month, then tail off around Christmas. This movement is very pronounced; while it relatively easy to find multiple Caspian Gulls in mid December, come January it is a struggle to find even one. Within this period, although good numbers may be present for a
    couple of weeks, there is usually one day in particular when there is a strong passage (this year 27 was the highest day count). But then suddenly they’re gone… where are they? The time when the Caspian Gulls appear is also the time when large numbers of argentatus Herring Gulls and Lesser Black-backs are moving through. As if all these birds have come in from the east (?) as part of one big combined movement. I wondered if the Lesser Black-backs continued west, even heading down to Iberia to winter (???) but whether or not this is the case it’s clear that the Caspos and Argies are not moving further west. Even in neighbouring West Sussex they are a rarity. So why do they stop here, why do they gather in such numbers and where do they go afterwards? I was interested to hear the rise in numbers of Caspo’s at Dungeness this winter IMMEDIATELY after the Sussex influx. While my local spots had emptied of birds, Dunge was enjoying counts of up to 11 birds. Does this suggest our birds moving back east? Looking at reports from the southeast region is it possible to get a clue what Caspo’s are up to – look at the timing of peak counts – in Norfolk in Oct/Nov, in East Sussex in December, at Dunge in late Dec/early Jan, in the Thames area in mid Jan – are the birds on a circuit? And what about Lesser Black-backs and Argies – are they sharing the same routes. Are peak counts of these associated with Caspo’s elsewhere in the region??? Any thoughts….


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