Thursday 5 June 2014

American Herring Gull x Glaucous Gull

American Herring Gull x Glaucous Gull hybrid, Siena Pond, Broomfield County (Colorado, USA), 7th January 2012 - copyright Steve Mlodinow
(photo ID: 1325)

Compared to some North American gull hybrids this one doesn't seem to be so common.  Here are some notes from Steve:
"Note the very Glaucous Gull like bill pattern, small eye like a Glaucous Gull, but bill a bit narrower than normal for that species.  Most importantly, note wing tips, which are slightly darker than tertials and remainder of wing, more like a Glaucous-winged Gull (which wouldn't have the pink bill, with black tip)."
American Herring Gull x Glaucous Gull hybrid (same bird as in photo ID 1325 above), Siena Pond, Broomfield County (Colorado, USA), 7th January 2012 - copyright Steve Mlodinow
(photo ID: 1324)

Some marvellous shots of the next one:

American Herring Gull x Glaucous Gull hybrid, Sequim, Clallam County (Washington, USA), 8th February 2009 - copyright Steve Mlodinow
(photo IDs: 2221-2223)

Steve says the next one appeared paler in life than the photo would suggest.  He adds,
"It had a rather straight, thick, long bill without much of a gonydeal angle... a fairly typical appearance for "Nelson's Gull" in my experience.  Note that the primaries are brownish and tipped white, not black.  Also, the back is pale gray (paler than that of Ring-billed Gull) with very sparse markings and the wing coverts had the salt and pepper appearance of a Thayer's or Vega (or Glaucous) Gull as opposed to the muddier appearance of a Herring Gull's wing coverts.  The bird was also stouter and larger than nearby Herring Gulls." 
American Herring Gull x Glaucous Gull hybrid, Pueblo Reservoir, Pueblo County (Colorado, USA), 23rd March 2014 - copyright Steve Mlodinow
(photo ID: 1572)

The next bird was some distance away and was digi-scoped by Steve. He says there are a couple of differences between how it looks in the photo and how it looked in life: the very straight edges to the bill (proximal to gonys) are not as striking as they were in life and the bill looked more bubble-gum pink than yellowish.  The body and back colour are portrayed more accurately, including the wingtips which were not that much darker than the body.  Steve also notes the flat headed, big-white-eyed look that many Herring Gull x Glaucous Gull hybrids seem to show.

American Herring Gull x Glaucous Gull hybrid, Windsor Lake, Weld County (Colorado, USA), 11th March 2015 - copyright Steve Mlodinow
(photo ID: 2138)

John tells us that the next bird stood out at first because it was so pale and he initially suspected it was a Glaucous Gull.  When it took flight he noticed the reduced black in the wing tip (compared with American Herring Gull).  It's the second bird from the left.

probable American Herring Gull x Glaucous Gull hybrid (with Great Black-backed Gull, left, and 2 American Herring Gulls, right), Goose Rocks Beach (Maine, USA), 18th October 2016 - copyright John Oates
(photo ID: 2875)

Steve comments on the next third-year bird:
It is hard to capture, in such dingy light, how pale backed this bird appeared.  When I first saw it at a distance, I thought it an Iceland Gull.  I quickly drove closer, and realized that the primary pattern was off, thought Thayer's Gull.  But the bird was distinctly paler than the nearby Ring-billed Gulls.  The bird was also large and aggressive, attacking a Common Merganser and stealing its fish.  The bill is relatively hefty, with an appearance that I have come to associated with this cross.  The only major issue is the eye color (which did look paler in life than in the pics, but not hugely so).  The distant pic of the bird on the water is give a feel for what it looked like whence not in flight.  The bill looked a bit different in life than in these photos: a bit of red next to the red, and the tip of the bill was also paler than the portion proximal to the band on the bill.

American Herring Gull x Glaucous Gull hybrid, Firestone Gravel Pits, Weld County (Colorado, USA), 26th March 2017 - copyright Steve Mlodinow
(photo IDs: 3190-3194)

American Herring Gull Larus (argentatus) smithsonianus
Glaucous Gull Larus hyperboreus

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