Thursday, February 14, 2013

Glaucous x Herring Gull hybrids in North Carolina

I was able to spend a few hours yesterday afternoon at a landfill in the Research Triangle area of NC. Birds numbered in the thousands, dominated by Ring-bills. There were several hundred Herrings scattered through the masses, as well as a healthy number of Lesser Black-backed and a handful of Great Black-backed Gulls. The highlight came in the form of two first cycle GLAUCOUS x HERRING GULL hybrids.

The first bird was a beautiful, subtle milky brown color, sporting brown primaries with thin white fringes. A large bird with a Glaucous-like structure and bill pattern.

sleeping


Flanked by young Herring Gulls. A lucky shot, note the pure white-winged bird with stretched wing to its right. More on that one below.

The second GLGUxHERG was more Glaucous-like in body plumage. In fact, when I first saw the bird from just the neck up, I thought I had found a Glauc. But it was easily ID'd as another hybrid by those brown primaries and tail.


vaguely reminiscent of a faded Thayer's Gull in this shot
dwarfing the first cycle LBBG (to the right, facing the same direction)



 

For comparison, here is a "white-winged" gull that appears to be a leucistic Herring Gull. The snow white primaries and overall white body plumage suggest a white-winged gull such as Glaucous, but the bird's size and structure seem spot-on for Herring. Also, note the dark brown tail and seemingly randomly placed pigment in some of the upperpart feathers including the tertials. It's not easy to age a bird like this, but given its slightly paling eye, thick black ring on the bill, and other features such as an apparently dark tail and barred undertail coverts, I would guess the bird is in its second cycle or thereabouts.



This was meant to be a photo of the hybrid GLGUxHERG (center), but note the leucistic Herring (center right) with its wing outstretched, revealing snow white primaries.

The number of Lesser Black-backs was impressive, with a one-time count of 22 in view at once. I picked that moment randomly, and it was my only count. Who knows how many were there...30, 40, more? A repeated, dedicated count, especially by age class, would reveal a more accurate (and higher!) number.



4th cycle
4th cycle
first cycle...looks delicious
first cycle
first cycle

first cycle LBBG (right) next to first cycle Herring (left)

adult

adult

second or third cycle

advanced first cycle or delayed second

adult

adult (the darkest adult of the day)

Not terribly exciting to someone from Connecticut, the "rarest" species of the day was Great Black-backed Gull, with at least 5 being seen (adult, second cycle, and 3 first cycles).

out of focus but this is the only one I have with its bill out
first cycle, same as above
first cycle dropping behind a ridge

likely worn first cycle versus delayed second cycle, the "pale" base of the bill is just mud

second cycle
the same second cycle as above
adult

I spent nearly 3 hours there yesterday but am already itching to get back. That'll have to wait until next winter though. The gulling was fantastic...much more interesting that I would have guessed inland NC had to offer. But the region has records of California, Thayer's, Iceland (several), and Glaucous (several) Gulls so it shouldn't have come as such a surprise. No pure Glaucous on this visit...just two mutts, but cool nonetheless.

 - Nick

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