Lesser Black-backed Gulls, Guyana, Nov 2016 - anything else?

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Chris Sharpe
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Joined: Sat Nov 12, 2016 9:06 pm

Lesser Black-backed Gulls, Guyana, Nov 2016 - anything else?

Post by Chris Sharpe » Fri Nov 18, 2016 3:35 pm

I wonder if anyone would like to take a look at the following photographs of 3+ Lesser Black-backed Gulls? Having been told that one of the birds is not a LBBG, I have posted these photographs elsewhere (on our Neotropical Bird Club Facebook page and subsequently Birdforum), but have had only a few further brief comments. Friends at NBC Council suggested that I re-post information here. I would be very grateful for any expert comments.

On 3 November, four of us - John Murphy, Nick Acheson, Steve Harmer and I - opted to do a little extra birding on the Georgetown coast on the final afternoon of our trip to Guyana. We chose a site not far from our hotel that we call Ogle seawall, the point at which Ogle creek meets the sea at a sluice gate (6.823N 58.099W). The site had proven to be quite good for coastal mudflat birds ten days earlier and we had been informed that high tide would be at 18h00, which augured well for mid-afternoon birding. Shortly after arriving at 15h15, John and I noticed two immature larger gulls amongst a flock of 600+ Laughing Gulls which were roosting on the mudflats, gradually moving E along the coast as the tide came in. Allowing for harsh light and bleaching, I thought that both birds looked like Lesser Black-backed Gulls Larus fuscus, but John was doubtful about one of them, due to its pale head and heavy bill. Knowing that these were likely to be few records of any large Larus, we both took photographs until the birds drifted off eastwards and out of sight. John's photos from 3 November are on Flickr. My own photographs of both gulls are of much poorer quality.

On 4 November, I took the opportunity of a day of meetings in Georgetown to visit the site again, inviting local birder Leon Moore to join me, since I was sure that this would be a new bird for him. We arrived at 16h20 and found a similar situation, with 820 Laughing Gulls and three immature larger Larus. We both obtained further photographs. My photos from 4 November are on Flickr. Leon's images are on Facebook.

A minimum of three immature (1st and 2nd cycle) birds were involved in these sightings, but our photographs are labelled Gull1 through Gull7 to group photographs that we know to pertain to the same individual. All birds were pink-legged. 2nd cycle bird(s) showed a pale iris and some dark grey mantle feathers, which (allowing for light) seemed to me to be the colour I am used to in typical L. f. graellsii (rather than, say, the ash grey of L. a. argentatus).

On return home, I immediately contacted Mark Robbins, author of the SACC country checklist for Guyana. He confirmed that Lesser Black-backed Gull is listed as Hypothetical for Guyana, with only one previous (as yet undocumented) sight record, by a BirdQuest tour led by Eustace Barnes in September 2012. There are no records of any other larger Larus species. I have contacted Eustace for details of his sighting.

Since then, one expert has identified one of the birds as something other than L. fuscus, which is why I am posting links to the images here. I would be very grateful for any further comments.

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marsmuusse
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Re: Lesser Black-backed Gulls, Guyana, Nov 2016 - anything else?

Post by marsmuusse » Tue Jan 17, 2017 3:21 pm

Hi Chris,
Not sure if there still is any relevance in an opinion from europe, anyway, here are thoughts on the Guyana birds:
#1 - pictures by John on Flickr, shows a 2nd winter graellsii type Lesser Black-backed Gull.
#2 - pictures by John on Flickr, shows a 1st winter graellsii type Lesser Black-backed Gull, moulting some scaps.
#3 - pictures by Chris on Flickr, shows a 2nd winter graellsii type Lesser Black-backed Gull, slightly different in partial autumn of the wing-coverts.
#4 - pictures by Chris on Flickr, shows a 1st winter graellsii type Lesser Black-backed Gull, with only flight shots difficult to be sure this is different from the Nov 3rd bird; overall seems to be darker chocolate brown.
#5 - to me looks identical to the #1 2nd winter graellsii type Lesser Black-backed Gull.
#6 - to me looks identical to the #1 2nd winter graellsii type Lesser Black-backed Gull.
#7 - to me looks identical to the #3 2nd winter graellsii type Lesser Black-backed Gull.

If you saw the gulls as group together, I am wrong of course in assuming there are only 4 birds in the pictures, but if the observations were made apart from each other with a time interval, I would take a second look at the subtle details in the wing-covert panel to exclude the possibility these birds are the same. Bird #1 has a particular pattern in greater covert #2 to #4 with a darker grey median covert on top and the worn lower rear scap, which, in my eyes, seem to be present in all birds labeled #1, #5 and #6.


In any way, great observations of course, well done!!!

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