We have available the quintessential Mod on animals, that will fill your worlds with a variety of species.
Mo? Creatures 1.7.2 and 1.6.4 is responsible of transforming the solitude in species of the animals game, in a world full of new neighbors, some of them hostile, with which you can interact in one way or another.

Detail and Download here : Mo? Creatures Mod

Homepage: Mods for Minecraft