Wednesday 15 August 2018

Dark Lesser Black-back - Edit

This dark juvenile Lesser Black-backed Gull was on Exmouth beach this morning. The overall darkness and dark bases to the greater coverts, forming a continuous bar, are features shared with Azorean Gull, but I'm not about to claim one here.  It has the required black 'shin-pads' of this species but so does the more typical Lesser Black-back below. The tertials look surprisingly well worn and the bird looks streaky below. Structurally the bird was a bit more Herring Gull-like than your more typical Lesser Black-back (again see below). Interesting bird.

Note the darkness of the upperparts and worn tips to the tertials. From what I understand, Azorean Gull retains its scapulars longer that Yellow-legged Gull, so wouldn't be expected to show signs of moult in the upperparts in mid August.

Azorean Gull shows a broad tail band (like Lesser Black-back and unlike Yellow-legged) and dark inner primaries much like that of Lesser Black-backed Gull, so nothing to suggest anything other than LEEB here, though the bases to the greater coverts form a continuous plain dark band, whereas in a typical LEEB the outer greater coverts tend to be dark based and the inners more patterned.

Edit - had overlooked this photo showing tail detail a little better (click on image to enlarge).

…..and some more photos to give a better idea of the bird's structure. There's some wear in the tail too.

This open wing shot shows a faint pale inner primary 'window', relatively short broad wings and almost solidly brown greater coverts. The outer web of T6 is white with small black 'indents'.
This is a more typical Lesser Black-backed Gull in both plumage and structure. It was also on the beach this morning. Note the outer greater coverts are dark-based and the inners are chequered. Also note the dark shin- pads.
Juvenile Yellow-legged Gull - no sign of any moult in the scaps on this one.

Six-striped Rustic

Dark form of Marbled Piercer, Cydia splendana

Orange Swift

Dark Sword-grass - 3 Silver Y and a Rusty Dot Pearl were the only other immigrant species.

Small Rufous

Flounced Rustic

Gold Spot

One of two Copper Underwing trapped last night.

Juvenile Marsh Harrier. I had a few things to do in Topsham this morning so I joined the crowds at Bowling Green. Spoonbill and Spotted Redshank seen amongst the usual stuff.

Juvenile Spoonbill


  1. Hi Matt, another 'interesting' bird! I've no experience with juv/1w atlantis so my opinion based entirely on photos and reading. If this is just a dark graellsii (and we've all seen a few), why is it so worn? I would have thought our local LBBG are amongst the earliest to fledge and all are now looking fairly fresh and nothing like this bird. So on this basis I think atlantis must be a serious possibility, proving it rather more difficult! On plumage and structure I don't think a definitive ID is possible - too much overlap - although will ask around and look for a more informed opinion. If you see it again try for a shot of spread tail - amount of white on T6 would be interesting. Cheers, Tim

  2. Hi Tim - many thanks for commenting. I'd overlooked a better tail shot and have now included it above. Not sure if it will be any use as still haven't found anything definitive on exact T6 pattern/extent of white. Look forward to hearing your thoughts. Thanks again. Matt

  3. That really is a stand out bird Matt, but like you I would leave it at that for the time being but keep up the research and asking around..