Folks- I headed to Cherry Creek Reservoir today with my dad Jim,
meeting up with Mike Freiberg when we got there. Birds on the lake
were scant, but a few dozen gulls were loafing at the east side, some
on shore and some on a small sand bar out from where Cherry Creek runs
into the lake. While scoping, one caught my eye from behind the group
as it bobbed its head up and down, bathing. Though I couldn't yet see
the whole bird, its head looked quite pale, with a dark eye and a
robust all-black bill. Soon it walked into view. We tried to slot it
into one of the two Black-backed categories without luck. A nearby
adult Herring Gull provided excellent size & structure comparison-
this bird was similar in size if not perhaps slightly more bulky. The
wing projection was similar, but the bill was thicker and had a more
pronounced gonydeal angle . I started to get a funny feeling of deja-
vu and angled around for some digiscoped shots.
Comparing the shots with those that I took on 28 November, 2008 at Six-
mile Reservoir in Boulder County, I think this is the same bird that
seemed to be a likely 1st-cycle Slaty-backed Gull (or at least a gull
cut from the same cloth.) The main difference I see is some
additional scattered dark feathers in the scapulars and maybe other
wing covert tracts (presumably newly molted in, expected in the
intervening 3 months?) Much of what I see in this bird is very
similar to a 1st-cycle Slaty-backed Gull from South Korea photographed
on 16 February in Steve Howell & Jon Dunn's Gulls of the Americas
(figure 30.8.)
I'd happily email a composite I made comparing similar poses of the
bird we saw today to that of 28 November in Boulder to anyone
requesting it. My hypothesis is that the bird made its way further
south after visiting Boulder (with sightings at Cherry Creek and
Pueblo Reservoir.) Where it spent the remaining winter is subject to
speculation, but perhaps it is working its way back up the Front Range.
We also had a couple of Harlan's Hawks (an adult and a juv, both dark
birds), and my dad & I found a Marsh Wren in the cattails SE of the
lake along Cherry Creek (south along the 12-mile House trailhead.)
Enjoy- Bill Schmoker, Longmont
______________________
• Bill Schmoker •
______________________
http://schmoker.org
http://brdpics.blogspot.com
[email protected]
720/201-5749
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