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