This fascinating blog post by Kaeli Swift gives some detailed insight into the topic of what controls feather pigmentation in birds, and in particular corvids.
Shared with the kind permission of Kaeli Swift of Corvid Research.
Generally, when I receive emails with the subject line “interesting crow” it’s because the author noted some peculiar or amusing crow behavior they want to share, or because they spotted an unusual looking crow due to AKD, leucism or avian pox. Rarely, it’s for none of these reasons and is truly a horse of a different color. Or in this case, crow.[…]