What White Means
This is a leucistic, or partial albino, robin; he has a lack of normal pigment (for color) on his neck and head. More white could also be a clue that he's an older robin. Robins seem to get more white by around the neck as they get older. They are still very capable of having babies, and more white feathers give them a certain extra appeal over the other guys. Male and female birds both want the oldest mate they can find. Why? Older birds have more experience, which make them more attractive to those looking for mates!

—Laura Erickson, Journey North's Robin Expert

Courtesy of Randy Indish