That species is black-capped chickadee, one of the more common species I see. The reason I know I’m not supposed to be seeing it is because E-Bird, Cornell Lab of Ornithology’s bird sightings site, considers it a "rare" species in my county and always asks me to confirm the sighting. E-Bird thinks I’m only supposed to be seeing Carolina chickadees. And if I lived down off the mountain, E-Bird would be right.
Ten years ago, I had to go in search of Carolina chickadees. Black-capped chickadees ruled the area. Carolina chickadees weren’t far to the south of me, though. Then a few years passed, and Carolina chickadees were reported at Pinchot park, just about three miles south of me. So I went to the bird blind where they were and waited what seemed like an awful amount of time, sorting through lots of black-capped chickadees until I finally found a pair of the Carolina chickadees.
Then a few years ago, I saw the first Carolina chickadees at the cabin. The Carolinas were much in the minority at my feeders, but occasionally, perhaps once or twice a week, I’d see the little, grayer birds and added them to my yard list. Last year, I was even lucky enough to get a photo of the two species side by side.
This year at my feeders Carolina chickadees are more in evidence, if not quite even with the black-capped chickadees. And, I’m seeing birds that I believe are intergrades of the two. It’s starting to make me wonder how they can be called two different species, but that’s a discussion for a different day.
Anyway, research shows that Carolina chickadees are moving further north, but also suggests that where the two more or less overlap black-capped chickadees do better at higher altitudes. So here up on Roundtop, the black-capped chickadee is still a common sight, but given the spread of the Carolina chickadees, I wonder how much longer that will remain true.