18 December 2013

Whiting Gulls: Kumlien's/Thayer's, GBBG Hybrid and Glaucous

I spent a few hours at the BP Refinery in Whiting, Indiana on Saturday. Highlights included a good count of 13 Great Black-backeds, an adult type Glaucous, a presumed GBBG x Herring and a Kumlien's/Thayer's type.

Clearly a shade paler than the pure GBBGs, the dark-backed gull (front-right) seen here is likely a GBBG with some pale-backed genes. Whether this is Herring or Glaucous influence (the two most likely mixes) is not clear. 
Four of thirteen GBBGs on Whiting Beach. Whiting, IN is one of the best sites to see Great Black-backeds on southern Lake Michigan. The birds are very skittish here, but can be found on the east side of the beach in relatively good numbers.
First cycle Great Black-backed.
Adult type Glaucous Gull (still growing outer primaries and central secondaries).
Adult Bonaparte's Gull. It's getting a bit late for Bonnies on Lake Michigan, but there are still a few filtering through.
My favorite bird of the day, I couldn't decide whether I wanted to call this a Thayer's or dark Kumlien's/Thayer's intergrade.
The wingtip pattern is fine for Thayer's (and that's probably what it will be logged as), but the pigmenation to the wingtips was a bit more slaty than I like. In particular, the outer web to P10  (which I expect to be dark) was wahed out and dark gray:

But as is always the case, at different angles, the bird appeared darker (especially from behind):