Carolina Chickadee or Black-capped Chickadee?

Due to climate change, the range of the Black-capped Chickadee and Carolina Chickadee overlap.

I was uncertain about the identification of this bird, so I uploaded the image to ChatGPT, requesting identification.

Me: Please identify the bird in this photograph. Please describe the scene.
ChatGPT: This is a photograph of a Carolina Chickadee, identifiable by its black cap and bib, white cheeks, and soft grey back, wings, and tail. It is perched on a bare branch amidst a network of similar branches against a pale blue sky, likely in a deciduous woodland during the non-breeding season when trees are leafless.

For verification, I uploaded the same image to the Merlin ID app. Merlin also identified this bird as a Carolina Chickadee. However, after additional reading on All About Birds, I learned that this individual could be a Carolina or Black-capped Chickadee. They are very similar in colouring, and identification can be challenging. The calls of the Black-capped Chickadee are different from the Carolina Chickadee. Unfortunately, I didn’t have the presence of mind to use the Merlin app for an audio identification.

However, Merlin ID mentioned a 2014 study by Cornell Lab of Ornithology, Villanova University, and Cornell University that indicates that the hybrid zone between Black-capped and Carolina Chickadees is shifting northward in alignment with rising winter temperatures.

This is the first time I have heard and photographed a Chickadee. I heard this individual's distinctive call when I was outside, about to leave on a short walk. The bird was in a tall tree in the small wooded area between two streets near my home. Despite the challenges of backlighting, I enhanced some of its features using Adobe Lightroom, drawing out the finer details that aided in its accurate identification.

Carolina Chickadee (Poecile carolinensis) · 30 December 2023 · FujiFilm X-T3 · XF150-600mmF5.6-8 R LM OIS WR

Carolina Chickadee and White-breasted Nuthatch

I've been using the Merlin Bird ID app to identify a bunch of birds hanging out in my backyard and even got some decent photographs of them. This morning, the app picked up the chirping of a Carolina Chickadee and White-breasted Nuthatch. The Carolina Chickadee is on the feeder, and the White-breasted Nuthatch is on the tree.

The Carolina Chickadee is a small, chubby bird with a large head that is a common sight in woodlands and backyards of the southeastern United States. It is the only chickadee found in most of its habitat. Its overall colouration is grey, with a distinct head pattern: a black cap, white cheek, and black throat. Its bill is short and stubby, which it uses to crack open seeds. It is often seen in mixed flocks of other songbirds and can be spotted at bird feeders.

White-breasted Nuthatches are familiar avian visitors, sporting distinct black, grey, and white patterns. These small and nimble birds are keenly interested in insects and sizable seeds. Their name originates from the peculiar behaviour of wedging sizeable nuts and acorns into tree bark, utilising their sharp bills to "hatch" the seeds. Despite their diminutive stature, White-breasted Nuthatches emit robust vocalisations, and their persistent, nasal yammering is a reliable guide to locating them.

Updated: I recently rediscovered this post and edited it with a new title, content and tagging. In 2017, I had no clue these were Carolina Chickadee and White-breasted Nuthatch.