Thursday 30 October 2014

(The) Yellow-legged Gull and its impostors

As the sun was setting today behind thick rain clouds the Yellow-legged Gull came into view for a group of birders from Massachusetts and myself.

It has almost completed its primary growth, far ahead of any of the Lesser Black-backed Gulls (15+) that I saw today. Also saw 3 (!) LBBG x HERG hybrids today - one of which was quite advanced in its primary moult (photos further below).

P10 pretty well completely grown; white mirror only on the outer most primary. Black on the 5 outermost primaries. Bright yellow almost orange legs. And no (very limited) streaking on the head all add up to a highly desired bird for North American birders.

But there are impostors that get in the way.
Today I saw a personal high of 3 Lesser Black-backed X Herring hybrids. Their mantle colour is more or less the same as YLGU but there are important differences between what is expected of the hybrid and YLGUs.

This bird really had us working. The streaking on the head is certainly more pronounced around the front half of the head, and limited along the back of the neck, and very limited on the upper breast. From a distance it had a somewhat hooded appearance making me think it was going to be a YLGU.

After 1-2 hours of following/watching this bird we were finally able to see the legs and got spread wing shots: 

Leg colour could easily pass for YLGU on this bird. But a few things don't line up: streaking (although limited) was seen on the upper breast, the red orbital ring was quite dull (almost pinkish), complete black band on P4 (at least on the left wing) - otherwise the wing pattern looks perfect for YLGU. Those small features make a big difference on the ID.

Iceland Gulls are starting to become ubiquitous in town. Saw 1-2 at most locations today, and 10+ at the epicentre of Iceland Gulls: Pier 17.
 These ones photographed today at the west end of Quidi Vidi - probably returning birds considering how tame they were:

This one was all dressed up for Halloween - pretty freaky looking if you ask me!