Friday 7 September 2018

An Obsession with Baltic Gulls

Since I started watching gulls regularly at Shawell in 2012 I thought the possibility of an identifiable Baltic Gull Larus fuscus fuscus turning up there seemed good. However, only colour-ringed birds are acceptable in Britain - oh and some 2CYs. At the time no 2CYs had been accepted in Britain, but maybe it would be worth reading up on them?

From time to time a jet black adult LBBG caught my eye, but there is quite a lot of overlap in features between fuscus and intermedius and so a positive identification of a vagrant is near on impossible. My first opportunity to claim a Baltic Gull came in 2014 when I saw J727 a Norwegian ringed Baltic Gull, but I didn't nail the ID that time and I missed the full scientific name whilst entering the ring reading.

My skills were improving all the time and in July 2015 I saw a second calendar-year LBBG on the landfill that shouted Baltic Gull! It had a full set of unworn new looking primaries, many black adult  like scapulars and coverts. Its greater coverts were plain brownish with no barring. Without going on, it matched the Altenburg Criteria for the identification of Baltic Gull in 2CY plumage - the only age when, from a vagrant point of view,  they are unique enough to be identified without a colour-ring from a known breeding area. I reported the sighting to the British Birds Rarities Committee (BBRC) in the hope that it would prove acceptable.

2CY Baltic Gull at Cotesbach Landfill site July 2015

In March 2016 another go at J727 presented itself and this time I identified it as a Baltic Gull. I had forgotten about my 2014 sighting, but as the record appeared on the screen of my phone I couldn't believe I had seen it before. The scientific name was L. f. fuscus, so my ID was correct. I submitted the record to BBRC, but due to some issues over Norwegian Baltic Gulls the record sat in the pending tray. A record of a colour-ringed bird (J154) alleged to be from Horsvaer was causing some controversy due to it looking too pale for a Baltic Gull. The photograph of this bird did the rounds on Social Media, which did nothing to promote any goodwill for the 'Horsvaer gulls'. Because of this I did not submit a sighting of another Horsvaer colour-ringed bird I saw shortly after the sighting of J727.

I discussed this issue with Morten Helberg in Norway, who has ringed many of the 'Horsvaer gulls' and been involved in the study of these birds. Morten invited me to see for myself, so in early August 2017 Morten and I visited Horsvaer. We ringed over 60 chicks and looked closely at the gulls. We decided that we should report what we jointly knew about these 'Horsvaer gulls'. Our plan was to publish it in British Birds.

Baltic Gulls, Horsvaer, July 2018

Morten convinced me to be the lead author and along the way we recruited Mars Muusse from The Netherlands who knows loads about Baltic Gulls. In all it took a full year from start to finish, but I'm very pleased with the result. We submitted it to BB in January 2018 and Roger Riddington seemed very positive. He sent it to various reviewers in Britain and elsewhere in Europe. The consensus was that it should be accepted for publication. However, there was a small list of comments to address. The biggest issue was that a photograph of J154 was added to the paper with a question of how does this fit in with what we were saying!

We addressed all the issues and then a couple of really good things happened. Firstly one of the chicks we ringed in 2017 decided to visit Sheffield and it ticked all the boxes for moult strategy of 2CY Baltic Gull. Next we managed to get hold of the original photo of J154 and it turned out that the code on the colour-ring actually read JT54. It looked like J154, but not all of the code was visible and the top of the figure that was read as a 1 was missing due to the angle, but on the underneath of the colour-ring the top of the T was just visible. JT54 is an intermedius bird from southern Norway not from Horsvaer - I was very happy when I spotted the top of the T 😁. The bird claimed to be J154 never sat well with me, as on my two visits to Horsvaer I had not seen a similar looking bird.

I'm proud to say that the paper appears in this month's BB and hopefully the 'Horsvaer gulls' will now be taken seriously in Britain.

In July this year, I was checked the BBRC work in progress file for some Leicestershire & Rutland Ferruginous Duck submissions and at the same time I couldn't resist checking if there had been any movement on my Baltic Gull submissions. I gave quite a cheer when I saw that they had accepted my 2CY Baltic Gull from 2015. They had also accepted two others: one from Norfolk and another from Suffolk. At the time of writing mine is the fourth for Britain in date order.

Again I am really pleased by this.

Who knows where this story will go but Morten and I are already talking about another project...

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