2011 Leucistic Carolina Chickadee
I lived in the Stoney Creek (Rockfish Valley) section of Wintergreen Resort in Nellysford, VA from 2006-2016. At that time, I knew of only one other avid birder who was a Wintergreen resident. However, many home owners had bird feeders. In 2009, I published a large, table-top book, A Photographic Guide to the Birds of Wintergreen. Soon afterwards, I received many messages and questions from residents about birds that they had seen there.
In 2011, I was contacted about a leucistic Carolina Chickadee that had been coming to a bird feeder up on the mountain section of the resort. It had also been seen several times on Wintergreen Drive. I tried to locate this bird several times, and was finally successful.
2011 Leucistic Carolina Chickadee
I posted the images of this bird on the ABA Facebook pages, and was informed that a leucistic bird completely missing one or more pigments was called "aneumelanistic."
In 2015, another sighting of an aneumelanistic Carolina Chickadee coming to a feeder was reported up on Crawfords Knob, which was accessed from Stoney Creek. I drove up there and saw this Carolina Chickadee. Although it looked identical to the 2011 bird, and was only 3.25 miles away from the 2011 sighting, there was no way for me to determine it was the same bird or ??
2015 Leucistic Carolina Chickadee
Yesterday, I received an email from Jay Gamble. He had seen another aneumelanistic Carolina Chickadee up on Wintergeen Mountain, and had read my reports from 2011 and 2015. The following map shows the locations of all three sightings. Please note that the individual homeowners have requested that specific addresses not be given where these birds have been seen. Jay posted his report and photos on eBird:
Jay Gamble's eBird posting
Aneumelanistic Carolina Chickadee sightings
These sightings raise some interesting questions. It has been almost 12 years from the 2011 sighting, and the resources I have found state that maximum lifetime for a wild Carolina Chickadee is 11 years. So is this the same bird? If not, is it an offspring with the same genetic characteristics? Is it even possible to pass aneumelanism from parent to offspring. Is there an entire family of these birds?
I asked Steve Rottenborn for his opinion, and here is his response:
These chickadees sure are interesting. I don't think these represent a different species or subspecies - of course, one never knows what "incipient species" might be produced at any given time by genetic mutations, but it would require the maintenance of individuals with those characteristics over hundreds or thousands of generations for us to start thinking about whether these features warrant species/subspecies-level recognition. More likely, this is a rare genetic condition that has, against the odds, persisted over several generations. Given that such birds are likely selected against, as they'd be easily visible to predators for most of the year in the environs of Wintergreen, I wouldn't expect these individuals to persist and spread their genes for too many generations, but it would be interesting to see how long such birds are around. They sure are striking to look at in those photos!