I was flicking through Sibley (not as painful as it may sound, by the way) in a recent idle moment and came upon the description of Lesser Black-backed Gull Larus fuscus which concludes with the paragraph, “Nearly all North American records are of the paler mantled Britain/Iceland population [graellsii]. A few records apparently refer to the darker Denmark population [intermedius], which has the same mantle-colour as Great Black-backed Gull [L. marinus] and relatively longer wings.”

I found this very interesting a) because I’m a bit anoraky and like that sort of thing, b) graellsii nests all around me in this part of the UK, and c) because of some photos I took in Miami some years ago that Sibley’s paragraph prompted me to look at again.

I took the photos below near Crandon Park in November. They clearly show a Lesser Black-back (the dark mantle, pale eyes, yellow legs, and heavily-streaked head confirm that - and the marks on the bill, worn coverts, and lack of primary tips suggest it’s probably a 3rd year bird), but I well remember at the time being struck by how large, bulky, and outright aggressive this particular Lesser Black-back was - I’d certainly not seen one that large for a while amongst the local graellsii, and while Lesser Black-backs are hardly shrinking violets, they’re not usually so dominant as this individual. The large size may be down to it being a powerfully-built female, but the very dark mantle - hardly contrasting with the wingtips at all - points very strongly to it being an intermedius.

Have a look and see what you think…(the birds in the background, by the way, are mainly Royal Terns and Laughing Gulls, and the young gull in the background of the second image is a Ring-billed)

I’m pretty certain this is an intermedius (of course feel free to disagree) and I’d be very interested if anyone could point me in the direction of a paper/article/website that looks at just how frequent this sub-species is in the US and where else it’s being seen. It seems surprising that the only Lesser Black-back I’ve seen in Miami should be a bird that has presumably flown even further than me to get there (and taken a lot more effort than me obviously), and I REALLY want to know what species the fish is that is being defended so strongly!

Comments would be very welcome…