Web accessible references on the topic (at least those I have on hand in
my citation manager).  Availability of berries relative to timing of molt in age classes is neat stuff.  Ordered by year, descending:

Flinn, T., J. Hudon, and D. Derbyshire. 2007. Tricks exotic shrubs do: When Baltimore Orioles stop being orange.  Birding 39(5):62-68.
http://www.aba.org/birding/v39n5p62.pdf

Craves, J.A. 1999.White-throated Sparrow with orange lores. Michigan
Birds and Natural History 6:87–88.
http://www.umd.umich.edu/dept/rouge_river/wtspreprint.html

Witmer, M.C. 1996. Consequences of an alien shrub on the plumage
coloration and ecology of Cedar Waxwings. Auk 113:735–743.
http://elibrary.unm.edu/sora/Auk/v113n04/p0735-p0743.pdf

Brooks, E.W. 1994. Diet-induced color variation in the White-throated
Sparrow. North American Bird Bander 19(1):12–13.
http://elibrary.unm.edu/sora/NABB/v019n01/p0012-p0013.pdf

Mulvihill, R.S., K.C. Parkes, R.C. Leberman, and D.S. Wood. 1992.
Evidence supporting a dietary basis for orange-tipped rectrices in the
Cedar Waxwing. Journal of Field Ornithology 63(2):212–216.
http://elibrary.unm.edu/sora/JFO/v063n02/p0212-p0216.pdf

Brush, A.H. 1990. A possible source for the rhodoxanthin in some Cedar
Waxwing tails. Journal of Field Ornithology 61(3):355.
http://elibrary.unm.edu/sora/JFO/v061n03/p0355-p0355.pdf

Hudson, J. and A.H. Brush. 1989. Probable dietary basis of a color
variant of the Cedar Waxwing. Journal of Field Ornithology 60(3):361-368.
http://elibrary.unm.edu/sora/JFO/v061n03/p0355-p0355.pdf

Cheers,

Dave
-------------
PWRC, Laurel