I don't have the same Sibley version you must have, but I believe the
double gender symbols are just a reference to the plural. i.e. in the
Audubon painting of the pileated woodpeckers in the given example, it
depicts 1 female (♀️) and 3 males (♂️♂️).
Hope that helps, if not some other smart birder will surely have an answer
for you.
Cheers,
Devon
On Sat, Jul 25, 2020, 20:17 Whitney Neufeld-Kaiser <
whitney.n.k at gmail.com>
wrote:
>
Hi, Tweets. I recently noticed that David Sibley uses double male and
>
double female symbols in his guide book, and I don't know what those mean.
>
I looked high and low for a legend, to no avail. Can anyone help?
>
>
If you have a Sibley guidebook or app sitting next to you, a double male
>
symbol shows up in the House Finch entry in the note that "some 1st year
>
[double male symbol] identical" to adult female. And the double male and
>
double female symbols both appear in his Pine Grosbeak entry with the note
>
that "some [double female symbol] and 1st year [double male symbol] have
>
russet plumage."
>
>
An example of the double male symbol is also here:
>
https://en.wikipedia.org/wiki/Pileated_woodpecker#/media/File:111_Pileated_Woodpecker,_b.jpg
>
>
Thanks!
>
Whitney Neufeld-Kaiser
>
Seattle, WA
>
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