Subject: Great Black-backed
Date: Jan 19 13:46:08 2004
From: Eugene and Nancy Hunn - enhunn at comcast.net


Tweets,

Following up on Ian's many helpful suggestions I've determined, on closer inspection, that the mystery bird at Renton is a most unusual hybrid of a Bonaparte's Gull and a Bald Eagle. Unprecedented, perhaps, but, hey, anything's possible.

Seriously though, I was able to view it at ca. 100 feet this morning (Monday, Jan 19) between 11:30 AM and noon standing on a log boom at the north end of Gene Coulon Park in nice sun. I can see no reason to think it's anything but a perfectly good example of a 2nd winter Great Black-backed Gull, with a bill that is a bit advanced, cf. 2nd summer. Nothing unusual about that. It's not huge but well within the range of a Great Black-backed in size. In particular, every plumage detail seems to match the photo in Grant of a 2nd winter bird with the greater coverts a bit more worn (figure 301, pg. 277, a November bird) with the bill transitional to the photos of 2nd summer birds (figures 302,303,304). The white spot near the tip of the outer primary is shown in Grant's figure 304 for a 2nd summer bird.

Sibley's illustration of a 2nd winter bird standing is a dead ringer, including the bill coloring and the P10 spot, though perhaps too clean gray on the scapular ground color.

The Idaho record from last December (2003) is clearly of a different bird, in 1st winter (cf. www.octoberweb.com/birds/gbbg).

Gene Hunn.
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