I had what I thought was a breeding plumage LBBG on Duxbury Beach yesterday that puzzled me in the field enough to make me think it might be some sort of oddity. Essentially it was - as I experienced it - a Great Black-backed Gull (GBBG) with yellow legs and a shorter, thicker bill than an LBBG. My concern lay in the fact that the yellow-legged bird was essentially the same size and the same very dark color as the GBBGs I'm used to seeing - neither visibly smaller nor the lighter, more charcoal gray that I would have expected from an LBBG.

It was with a dozen or so GBBGs and a handfull of other gulls at the ocean's edge just north of Plum Hills (a jogger flushed the flock and this bird and one other headed south toward Gurnet where I was able to pick it up about 1/4 mi. north of the Gurnet guard shack). As a group the gulls were quite wary, but I was able to get close enough to get decent photos with 400mm zoom lens. I observed it for a combined total of about 20 minutes at the two spots between 10:15-11:10 (high tide was 9:15am). In every respect it seemed like a GBBG - socializing comfortably - and I wouldn't have thought it was anything other than a GBBG except that I had noticed the bright yellow legs while checking through the shorebirds interspersed among the gulls. I was at first confused by the plain head and then recalled that in breeding plumage the LBBG's smudges disappear in an adult and concluded that because of color and size maybe this was an LBBG-GBBG hybrid - i.e., a yellow-legged short-billed GBBG - or else something more exotic, and so I started taking photos so I could try to figure it out when I got home.

After looking through a couple of "gull books" and other guides and comparing my photos and my recollections with their content I came to the conclusion that this individual doesn't fit any of the classic descriptions and must be an oversized LBBG with an unusually dark plumage - presumably the "intermedius" race which I don't typically see. None of them mentioned that GBBG's could have yellow legs. Some experts did me the favor of looking over the photos and they unanimously said that it was just what it looked like - a GBBG and yes yellow legs are not unheard of. Subsequently I found 2 photos on the web that look like this bird. So.. GBBG not LBBG.

The following 7 photos show various aspects of the bird with a sentence or two highlighting why that photo is included.