It can be done, I've looked into it for the Expansion several times.
1: A side for every animal on the foodchain, they cannot share sides. This in itself limits the potential biodiversity.
2: The eat command doesn't work with corpses, so instead, a programmed on-death drop for each creature.
3: Because there's only one possible eat command, each animal can have exactly one prey creature/item, and one predator creature, to get around this, there's always the option of using a "proximity" type script, though whether that works smoothly with items is dubious.
4: Notrium is unfortunately slightly loose when it comes to sticking to maximum populations, but the general figure is notionally in place in every spawner in the game.
I came to the conclusion that it wasn't going to be worthwhile investing effort into it unless that was the entire theme of the mod.