Now that I am regularly traveling the mid-Atlantic area I have subscribed to the Maryland, Virginia, and Carolina birding listservs. Several recent posts on these listservs are reporting Black-capped Chickadees entering en masse the traditional territory belonging to Carolina Chickadees. They are such similar looking birds, this could pose all kinds of identification challenges and exciting opportunities for birders to see a new bird!
Carolina Chickadees have been present at almost every location I have birded in the mid-Atlantic and I finally got off a couple decent photos. I love the blurred autumn foliage in the background. These photos were cropped, but otherwise unedited.
I have studied up in my assortment of field guides on the differences between the two species with some of the key traits portrayed below. Before I even looked in my field guide, I knew the Carolina Chickadee when I saw it. My gut just tells me that it is smaller. Carolinas certainly sound different than a Black-caps (click on name to listen). The belly color seems more consistenly yellow/buff to me on the Carolina Chickadee, but a look at photo guides doesn't support my theory. If you are really used to seeing one of these Chickadees, your eyes and mind will tell you when you see one that looks just enough different. I would love to see them side-by-side for easy comparison, but below is the best I can do for now.