Sunday, March 1, 2009

Cherry Creek Reservoir

March 1, 2009

Richard Stevens:

While doing chores I passed through Cherry Creek Reservoir (Arapahoe County). What a beautiful day with temperatures in the mild 60s; winds were calm(ish).

I scoped the eastern sand spit for the first winter Slaty-backed Gull reported yesterday by Bill Schmoker; without success.

I did find an interesting Gull among the 60 or so gulls (Ring-billed and Herring Gulls). This Gull had a dark mantle but not near as dark as a Great Black-backed Gull or even Lesser Black-backed Gull. It was the same size or slightly bigger than the adult Herring Gull standing next to it.

Its head and neck had scattered brown streaks. When it stood it revealed bright pink legs. The yellow bill had a darkish reddish spot near the tip. It was too far away to tell the color of its eye.

This Gull fit the description of an adult Slaty-backed Gull? Could an adult and her offspring have migrated to Colorado together? I watched the Gull for about an hour. It changed position several times so I could see the color of the mantle. It appeared much darker than a Herring Gull or not? The color could still be a result of the light (which was mostly back lit).

I have seen several Herring Gulls that looked like the description that Bill Schmoker gave of his possible first winter Slaty-backed Gull. Perhaps they are hybrids of some type? In both cases, I figure his and my gulls were Herring Gulls. Will look further into them.

Several people eventually walked by and scared up all the gulls which then flew west. I plan to return tomorrow for another look.

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