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Since late December, I have regularly seen a very pale Pine Siskin among the large flock of siskins at my feeders. Recently,
the light bulb finally went off in my head to research this bird a little further. Initially I set out to make sure I wasn't
passing off something significant like a Eurasian Siskin. It is not a Eurasian... but still very interesting: it appears to
be a "green morph" Pine Siskin. The bird in question is shown in the two pictures that follow:
I admit that I did not have much previous knowledge of these so-called "green morph" birds, and indeed there is not a
whole lot of information on the topic available in the usual sources. None of the major field guides mention it (at least
not the ones I have on hand), and a Google search doesn't turn up any obvious "authoritative" source. But there are some
important references, most notably a paper by McLaren et al. in Volume 43, Number 5 of American Birds (published
1990), a scan of which can be found here:
Drawing from this and other sources, it appears that the key features of green morph (especially as related to spearation
from female Eurasian Siskin) are:
- Lack of yellow in the supercilium
- Median coverts tipped in buff (not yellow)
- Rump often tinged in yellow
- Extensive yellow at base of tail
- Subdued streaking on the underside (as opposed to the more extensive streaking of both female Eurasian and typical
Pine)
- Yellowish wash on undertail coverts (not white)
All of these features are apparent on the bird pictured above. I think female Eurasian Siskin is easily eliminated, and
further, that this appears to be a green morph Pine Siskin.
I am reasonably certain that the pictures that follow are also of the same bird, but sometimes the flock can be very
difficult to follow. Additionally there are a few "pale" siskins among the flock that are definitely typical Pine Siskins
at an extreme of variation to add confusion. Though I think there is only one green morph, there is the possibility that two
birds are present.
A few questions:
First, can this identification be disputed in any way?
Second, how unusual is this morph, both in general and specifically in Pennsylvania? I admit I can't find very much information
on the topic, especially as it relates to Pennsylvania.
Many thanks to the ever-resourceful Paul Hess for assisting with finding relevant sources on the topic, including some
print sources I do not have access to.
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