On the unconfirmed-but-anecdotal-evidence-exists side, we know that salamanders and frogs might fart, but have weak sphincters and so probably don't fart audibly. Baboons fart, and apparently females who are swelling (their butts swell and redden to indicate fertility) produce the worst toots. Chimpanzee farts are made worse by figs, cynometra seeds, and fiber. They are "so loud and frequent we locate them in [the] forest occasionally by following the farts." As for bats, "the bigger they are, the harder they fart."