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Update; January 19, 2001: click here to see a "normal" green-morph Pine Siskin from Newfoundland.

This page demonstrates and discusses my recent encounter with a green-morph Pine Siskin (Carduelis pinus):

With higher-than-normal numbers of Pine Siskins (PISI) at my feeders in December, 2001 I had been enjoying close studies of up to six at a time, and on December 29 I was looking to see if my heavily-marked bird (see first siskin web page) would make a reappearance; instead I glimpsed a very bright, yellow-and-greenish individual at my sunflower feeder, and grabbed a quick snap through the window; even this fuzzy photo (with a female House Finch behind it) shows how striking it was:

Luckily it moved to one of my thistle feeders, allowing me to get better photos:

note in the first image above, the pointed outer tail feathers, making the green-morph individual a first-basic - compare it to the more-rounded tail of the adult normal PISI above it (from Pyle et al's banding guide).

- after a few minutes all the birds flushed; most returned, but I have not since seen this individual.

- compare a close-up of the wing of the green-morph bird to that of wing of the normal PISI from the above photo, followed by another close-up of the green-morph bird from a different photo:

- the bright yellow in the outer retrices made it difficult to assess the undertail coverts:

I know of two articles describing the green- morph PISI: "Eurasian Siskins in North America - distinguishing females from green-morph Pine Siskins" by McLaren, Morlan, Smith, Gosselin, and Bailey; American Birds, Vol 43 number 5 ( Winter 1989); "Identifying Eurasian and Pine Siskins" by Lethaby; BIRDING vol 30 number 2 ( April 1998).

The first-referenced article above did the ground-breaking work on the hithero-undescribed green-morph PISI, and Lethaby largely re-stated the conclusions in his piece (that focused more on separating normal PISIs from EUSI). To summarize green-morph birds:
a) they are (thus far) all males, presumed to be examples of schizochroism, in that the brown pigments are reduced/absent, while the green and yellow pigments are enhanced.
b) they have larger-than-normal amounts of yellow in the tail and in the wing base - much more than on EUSI.
c) they have yellow on the flanks and undertail coverts, but not across the upper breast - EUSI has white undertail coverts and flanks, with a yellow wash on parts of the face and across the upper chest (note that Lethaby feels some EUSIs can also have some yellow on the flanks).
d) the underparts streaking is reduced such that the upper (chest) streaks resembe the thin streaks of EUSI, but the lower flank streaking is also thin - very different from EUSI's thick, well-defined lower flank streaks. The extent of streaking is typical for PISI in that it meets across the breast, while most EUSIs have little or no central streaking.
e) The wing bars are typical of PISI in that they are both rather narrow, with a white median covert bar and a slight tinge of yellow in the greater covert bar (some of this effect comes from the bright yellow transverse primary patch showing though the feather tips), - EUSIs have thicker median and greater covert bars and both are genuinely tinged with varying amounts of yellow.

The Fort Worth bird above appears to establish that some of these criteria are not reliable, in that:
1) it does have bright yellow in the tail, but nowhere near as much as in previously documented green-morphs - and I feel it is within the range exhibited by EUSI.
2) the yellow in the base of the primaries is rather small - smaller than an average PISI, and again within range of EUSI.
3) The pattern of streaking (but not the extent) is an extremely good match for EUSI, in that the upper streaks are fine but the lower flank streaks are thick, blackish and well-defined.
4) The median wing bar is distinctly tinged with yellow, and thicker than normal for PISI - but perhaps still slightly too thin for EUSI?
5) The greater wing bar is tinged with yellow throughout its length, and not mainly as an artifact of an underlying yellow primary patch - but again it is probably not thick enough for EUSI. NOTE: there is evidence of wear in the plumage of this juvenile/first-basic green-morph bird - compare the edges of the tertials with those of the normal (adult) PISI - thus the wing bars may originally have been thick enough to match EUSI; all published pics of female EUSIs are adults (stated, and evident based on tail shape), and thus probably fresher (= thicker wing bars); for example this adult female EUSI by Nick Lethaby, from Japan:

So why isn't the Fort Worth bird a EUSI? (apart from the fact it was in Texas!):
i) the bill looks to be normal for PISI (although I feel there is some overlap in bill shape with EUSI, and thus this does not rule out EUSI).
ii) in the field I could not see any yellow on the undertail coverts, but the photos seem to show a small amount - EUSI has pure white undertail coverts.
iii) EUSI would have more yellow across the breast, and most have more yellow in the face (although the FW bird does have traces of yellow in the supercilium and auricular crescent)
iv) the extent of underpart streaking is at the extreme end for EUSI and normal for PISI.
v) the wing bars are not thick enough (altough this may be affected by wear).
vi) the pattern of the folded primaries - see 3rd siskin page.

As always, I would value informed comment on this page - please indicate whether your comments are to be considered private/anonymous - thank you.