[CT Birds] Pine Siskin video/green morph

Chasbarnard at aol.com Chasbarnard at aol.com
Tue Mar 3 12:26:45 EST 2009


Scott,
 
I think that the individual which you photographed is a green "morph" pine  
siskin.  However, it is not regarded as a separate race (subspecies), nor  is 
it clear that the green morph is really a morph, such as the morphs  of screech 
owl. 
 
The following is from North American Birds Online from Cornell. If I  
understand it correctly, they are saying that the color variation may come about  as 
a result of what the birds are eating ("differential access") at the  time of 
molt. This situation is also found in cedar waxwings, which show color  
variation in plumage, supposedly due to the diet at time of molt. If I have  
misunderstood this, I would ask those with a better science background than I  have 
to explain. 
 
Charlie Barnard
Stratford
 
Aberrant Plumages
Very small percentage of male individuals in collections have  darker and 
more greenish coloration above, paler and less extensive streaking  below, and 
more extensive areas of yellow on base of remiges and rectrices. This  plumage 
has been called “green morph” and is believed to result from  schizochroism in 
which phaeomelanin (brown pigment) is reduced or absent while  both eumelanin 
(black) and carotenoids (yellows) are retained. Darker green  individuals may 
have an extra dose of carotenoids (_McLaren et al. 1989_ 
(http://bna.birds.cornell.edu/bna/species/280/articles/species/280/biblio/bib069) ). Whether this 
plumage represents a  true color morph or individual variation (e.g., in 
another fringillid, the House  Finch [Carpodacus mexicanus], the amount and type of 
red  coloration varies individually and is related to differential access to  
carotenoid pigments at time of molt; _Hill 1993_ 
(http://bna.birds.cornell.edu/bna/species/280/articles/species/280/biblio/bib048) ) remains uncertain. 
McLaren et al. (_1989_ 
(http://bna.birds.cornell.edu/bna/species/280/articles/species/280/biblio/bib069) ) examined more than 1,500 Pine Siskin specimens  from 
6 museum collections and found 1% to be “greenish” individuals, all of  
which were male. Greenish individuals have been photographed in the wild in  
Halifax, Nova Scotia (Mar–Apr 1986), and in Arcata, CA (Feb–Mar 1987). McLaren  et 
al. (_1989_ 
(http://bna.birds.cornell.edu/bna/species/280/articles/species/280/biblio/bib069) ) summarized what is currently known about this  unusual 
plumage
**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
steps! 
(http://pr.atwola.com/promoclk/100126575x1219957551x1201325337/aol?redir=http:%2F%2Fwww.freecreditreport.com%2Fpm%2Fdefault.
aspx%3Fsc%3D668072%26hmpgID%3D62%26bcd%3DfebemailfooterNO62)



More information about the CTBirds mailing list