This Blue-headed Vireo (Vireo solitarius alticola) is the larger of the two subspecies. The smaller one, Vireo solitarius solitarius, migrates down to Mexico for the winter before returning to breeding grounds in Pennsylvania, New Jersey, and Canada.
As you can guess from my photo, the former chooses to overwinter along the Gulf Coast, a super long commute from their home territory in Georgia. Why go the extra distance if you don’t need to?!
As the binomial suggests, these birds do not flock together. At least not with their own kind (though they can occasionally be seen hanging out with sparrows).