Two winters ago (1992-93) we had an interesting phenomenon at our feeder in
Medina -- what we thought was a Black-capped Chickadee with a pure white
tail. One could see it at practically any daylight hour with no more than a
five-minute wait. But we were wrong. One day while filling the feeder my
wife realized that there were three chickadees, all with identical
pure-white tails, queuing up waiting for her to finish. After that we kept
closer watch and JoLynn believes that altogether there were in fact four
white-tailed chickadees forming what we presumed was a family. They
disappeared with the breaking up of the winter foraging flocks. The next
year we had one chickadee that appeared from time to time with prominent
white outer tail-feathers. This fall, so far, all of the Black-capped
Chickadees at the feeder have been unremarkable in their plumage.

Hal Opperman
halop at continuum.com
JoLynn Edwards
jolynn at u.washington.edu