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Posted by John Boyd on 15:18:08 01/01/07
In Reply to: Mystery Duck at ECO Pond posted by Trey for Paul-the-other
There's nothing unusual about the bill color. It's just an immature scaup, as the buffy patches at the bill base also indicate.
Since it has just been diving (see the water dripping off in the photo), head shape is pretty unreliable for ID of Greater. I agree the head shape looks like Greater in the photo. It's just an unreliable judgment under the circumstances.
I was initially impressed by the bill too, but after looking at some Lesser Scaup photos, I don't find it as convincing.
We saw it on Saturday during the CBC and marked it as Lesser. It didn't really stand out then one way or another. It was always across the pond and usually diving, so we couldn't really tell. Since virtually all scaups in S. Florida are Lesser, we called it Lesser. I meant to go back and look more closely with a scope, but was distracting by chasing Orchard Orioles late in the day (2 across the road from the lodge in the kingbird/scissortail area) and forgot to go back.
Based on the account in BNA, eye color indicates an immature female. They say Greater should be bluish green in young females and green-yellow in males while for Lesser, "Trauger (1974) described irides of known-aged females using Munsell color charts. One-year-old birds typically have brown or brownish olive irides, similar to those of juveniles. Two-year-old females have variable iris color, generally yellowish brown or light olive brown." This seems to indicate Lesser, although the iris looks a bit odd. It may be the result of overly aggressive noise reduction, smearing both detail and color (the whole photo looks that way).
CBC records indicate only 1 Greater Scaup on the Coot Bay CBC(1997). I don't know if there was any documentation of the sighting (no mention in FFN). Approximately 250,000 scaup have been reported over the years as Lesser on the Coot Bay CBC, but I expect few have been carefully scrutinized. The only earlier reports of Greater in Monroe County (there are none in Miami-Dade) were considered questionable by Stevenson and Anderson.
Given those numbers, there is a heavy burden of proof to establish it as Greater.
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