Saturday, February 23, 2013

first cycle Slaty-backed Gull in CT?

 [Feb 25 update: We have received correspondence from a couple of authoritative larophiles from other continents with SBGU experience. Both have stated that this could very well be a good Slaty-backed Gull but there are some concerns, with leg color and structure being mentioned most often. No deal-breakers though. Other possibilities include a very atypical smithsonianus HERG or a hybrid of New or Old World species. As one of them put it "it certainly looks so similar [to SBGU] that it would be worrying if it is something else entirely!"

The bad news is that we're no closer to knowing what this bird is. The good news is that their concerns echo our own, which shows that most of us seem to be on the same page here.]

A few days ago Mark Szantyr found an interesting first cycle gull at the Windsor Landfill that seems like a decent candidate for Slaty-backed Gull. I carpooled to the fill this morning with Julian Hough and Jake Musser to find a small group of birders already working the flock. After a bit of time we located Mark's gull and studied/photo'd it until it started to get uncomfortably wet.

All photos below are completely unedited except for cropping. Conditions were overcast with a light mist/drizzle. Click thumbnail for larger image. Take a look at all the photos as size, structure, and even plumage features seemingly vary from photo to photo.

I'm going to leave the comments to a minimum here, at least for now. The question here is, how identifiable is a first cycle Slaty-backed Gull in North America? Can it be done with confidence? If so, does this bird fit the bill? For example, can a worn, faded smithsonianus Herring Gull or hybrid be ruled out?

If you have any thoughts, please feel free to use the Comments section at the end of the post. I will likely respond by playing devil's advocate in either direction :-) Otherwise, enjoy this head-scratcher. Bigtime kudos to Mark for picking out this bird and bringing it to our attention.

marked by arrow, to give a feel for how it looked among the flock

center, body facing away, head turned right

center, in profile

wings raised

center, facing us

with first cycle GBBG behind

from left: GBBG, subject bird, HERG, HERG

facing left, with GBBG behind, HERG at far right

Of the two young birds here, the subject bird is on the left, and a first cycle HERG is to its right

among Herring Gulls

subject on left, HERG on the right

I currently do not have an opinion on this bird (and I'm not alone). Much more research is needed, all of which could be for naught; this one may go unidentified. I personally have seen zero SBGU of this age. On the other hand, I have seen thousands of first cycle Herring Gulls, and we know how ridiculously variable HERG and HERG hybrids can be...

Check out images of the same bird by Mark Szantyr, Julian Hough, and Joseph Cala so you can get a feel for what it looks like under different conditions/cameras/edits.

 - NB

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.


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)



second or third cycle

advanced first cycle or delayed second


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

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