Southern forests and swamps have a certain number of predatory animals, but by far the most dangerous ones are other *advertiser censored* Sapiens.
In the end, the other wildlife is more dangerous in theory than in practice:
Alligators do not actively hunt humans and will almost always leave adult humans alone if left alone. Exceptions can be made when humans present themselves as easy meals of opportunity or pests by entering or walking very close to the water at dawn or dusk, swimming fully immersed, stumbling over or messing around with an alligator- especially during nesting season etc.
Poisonous snakes? They do exist, but unlike their extremely poisonous cousins on other continents, US poisonous snakes and other creepy crawlies are relatively not that poisonous. Sure, people have been killed, but its usually the result of an allergic reaction or from leaving the bite untreated for days.
Quicksand? Very common in movies, less common in reality- if it even exists at all in the "suck'em down" sense of the word.
In short, unless he killed himself, there is a very good chance that he did not fall victim to ferocious fauna and is alive and doing relatively well.