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David Sibley

Urging caution when identifying Common Redpolls

Redpoll identification is challenging because Hoary and Common Redpoll seem to show an unbroken continuum of variation from pale to dark, and there are no fully reliable differences. So birders have to rely on a subjective assessment of overall color and struggle to define the threshold for confident identification. Virtually all birders see redpolls only

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A Character Index for Redpoll identification

[edited 12 and 14 Jan, 2008, adding comments about the index] I’ve been thinking about redpolls more, and had another, more careful, look at Troy’s 1985 paper, which is filled with interesting observations and some serious “food for thought”. First of all, Troy identified redpoll specimens using a character index, which is a well-established method

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Parula Hybrids?

I have had two inquiries about Tropical Parula in the last 24 hours, prompted by a bird currently in Austin, Texas. You can check out that bird in photos by Andy Balinsky and photos and some background by Martin Reid. It has the throat pattern and extensively yellow underparts of Tropical Parula, but the pale

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The Redpoll Questions

More thoughts on redpolls after yesterday’s post, prompted by my own nagging doubts and a query from Nick Anich: In all of this redpoll ID discussion, I think people ask the general question “How can I identify a Hoary?” when what they mean is the more specific question “Just how pale/small-billed/unstreaked does a redpoll have

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More on Redpolls

After my previous posts on redpolls here and here, I’ve had a chance to skim some of the redpoll literature, and it confirms that these are two very similar species (gasp! really?). Two papers in particular by Seutin et al (1992, 1993) offer some interesting observations. They conclude that it is possible to classify specimens

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