This morning I saw a green morph Pine Siskin among the many typical
siskins at our feeders adjacent Brookbanks Ravine in Toronto.
Compared to heavily streaked brown morph siskins, green morph birds
lack or have reduced brown pigments (phaeomelanin) exposing the
underlying feather colours. Green morphs are greyish (not brownish)
with a slight greenish hue to the upperparts and the underparts are
lightly streaked, usually there is more yellow in the wings/tail, and
the undertail coverts are often yellow (not always) unlike typical
brown morph birds.
The greenish hue seems to be mostly a mixture of yellow (carotenoid)
and grey (eumelanin) pigments. The amount of yellow in siskins seems
to vary independently. Some green morphs may be more yellow simply
because we see the yellow that normally would be hidden by brown
pigments. Other Pine Siskins show a lot of yellow and yet are normal
in terms of their brown and black coloration. I wouldn't call these
green morphs, but simply yellower (xanthochroic) siskins. Perhaps the
Sibley Guide (2000) was trying to cover both cases with the yellow
adult male Pine Siskin on page 534.
This is one of the best winters for Pine Siskins in a decade. Watch
for green morph birds, which comprise about 1 in 100 siskins. They
are sometimes confused with Eurasian Siskins. See ID article
http://fog.ccsf.cc.ca.us/~jmorlan/siskin_scan.pdf
I thank Michel Gosselin, one of the authors of the above article, of
the Canadian Museum of Nature for information on green morph Pine Siskins.
Directions: Brookbanks Ravine is east of the Don Valley Parkway
between York Mills Road and Lawrence Avenue.
Ron Pittaway
Minden/Toronto ON
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