[Tweeters] Black-Capped Chickadee with white tail

[dgrainger at birdsbydave.com]

There is a Black-Capped Chickadee on our feeders with a white tail. I 
took a number of photos (Port Townsend, WA on Castle Hill.) I am curious 
as to whether this is an aberration or is it simply a molt phase where a 
black feather is gone revealing a white one... I would be happy to email 
the image privately to anyone that would look at it and advise... Dave 
Grainger