Some hundreds of years ago, all humanity was removed from the Americas. In fact, most humans are gone from the world altogether. In the intervening time, nature has overrun the formerly human dominated landscapes of the former United States.
The area in question is immediately west of the Mississippi River as far as Texas, mostly corresponding to Louisiana and Arkansas today. Swampy bayous in the south give way to the forested Ouachita hills in the north. Water is plentiful year round. Due to latent global warming, the winters rarely freeze, and the summers are brutally hot and humid. The perfect conditions for wildlife.
Not only have the native wildlife been expanding over the last hundreds of years, but whatever animals left by humans also had a great opportunity to colonize the Americas. This brings us to the most populous vertebrate of the Americas as of humanity's departure: the humble chicken.
The chicken (or junglefowl, as it prefers to be called) originally hails from the subtropical and tropical forests of India, China, and southeast Asia. In the United States, there isn't much competition in its niche; the only similar birds native to the southeast US are the smaller Ruffled Grouse and the larger Wild Turkey.
On the negative side, there are plenty of predators for these new chickens out there, from bobcats and (formerly) domestic cats, coyotes and (formerly) domestic dogs and the many hybrids that will form between them, to mink, badger, weasels, foxes, and plenty of birds of prey. Also, probably 99% of all chickens are kept in conditions which will result in their swift death as soon as humans are removed. The silver lining there is that the less genetically-engineered-for-the-table free range chickens are the ones that will survive.
So, given the available evidence, will chickens be able to maintain a toehold in the post-human ecosystem of the southeast US? Will chickens make it?