Monday, November 17, 2014

Nov 9 - apparent hybrid Herring x Lesser Black-backed Gull in CT

I spotted this interesting adult gull as I pulled into my parking space at Long Beach in Stratford, CT about a week ago. It immediately struck me as Herring Gull-like but darker mantled. A quick check of eye color showed a bright pale yellow iris...unfortunate, as this one feature lessens the chance at something mega rare like Vega Gull. Anyway, a glance at a few other features all pointed strongly towards HERGxLBBG rather than a pure bird of some rare taxon. ID points are included in photo captions below.

the right-most bird next to two typical adult American Herring Gulls

Head/neck streaking showing a concentration of fine streaks around the eye that is often seen in LBBG, but thicker on the neck and breast than in your typical LBBG (note that winter head streaking is notoriously variable in HERG).

The dark mantle makes those scapular and tertial crescents really pop. Leg color was ambiguous to me at first...I had to talk myself into seeing definite yellow tones. More below on that.

Structure struck me as very Herring Gull-like...not small, slim and long-winged like LBBG. This was especially apparent on the couple occasions when the bird was directly next to HERGs.



Looking a bit more elongated in this photo.

No retained primaries. P9 and p10 are still growing.





Orange orbital ring. For reference, Herring Gull typically has a yellow-orange orbital ring at this time of year, and Lesser Black-backed Gull should show a reddish orbital ring.




I'd call these legs a yellowy flesh color, with yellow tones strongest on posterior legs and feet. They are less yellow than most presumed hybrid adult HERGxLBBG of which I have seen photos.



An interesting primary pattern, with less black than expected and rather bold white tongue tips (creating a "string of pearls" look).

Overall, I think this one's pretty safely identified as Herring x Lesser Black-backed given the suite of intermediate characters. The only thing that struck me as odd was the primary pattern. Perhaps these Herring Gull genes come from a population that shows less black in the wingtips, like the birds that are typically seen in Newfoundland (which average less black in their wingtips than our local southern New England birds)? If you have seen a putative HERGxLBBG hybrid with such bold white tongue tips, I'd love to hear from you.

 - Nick

No comments:

Post a Comment