The phenomenon is called xanthochromism. Not much seems to be known about it, except that it is fairly commonly observed. There are some hypotheses that suggest that the cause is often environmental and perhaps dietary in birds.
Hugh On Tue, May 6, 2014 at 11:48 AM, Bruce Horwith <bruce.horw...@gmail.com>wrote: > David Sagman sent me a photo of an interesting yellow-tinted hairy > woodpecker. If anyone knows about this phenomenon, info would be much > appreciated. > > https://www.flickr.com/photos/39025168@N07/13936633598/ > -- > *NYSbirds-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/NYSbirdsWELCOME> > Rules and Information <http://www.northeastbirding.com/NYSbirdsRULES> > Subscribe, Configuration and > Leave<http://www.northeastbirding.com/NYSbirdsSubscribeConfigurationLeave.htm> > *Archives:* > The Mail > Archive<http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html> > Surfbirds <http://www.surfbirds.com/birdingmail/Group/NYSBirds-L> > BirdingOnThe.Net <http://birdingonthe.net/mailinglists/NYSB.html> > *Please submit your observations to **eBird*<http://ebird.org/content/ebird/> > *!* > -- > -- Hugh McGuinness Washington, D.C. -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
