^ yeah theyre supposed to be real complex languages.
I SEE IT LIKE THIS:
Every animal which is born with a voice box has a set sound. A bark, a meow, a screech, or a chirp all were designed so animals can pick out who they speak to (ones that sound like them). They learn from their parents and others like them what means what, same as humans. Only they could give a fuck what we have to say.
Sometimes in places such as the woods, animals pick up on other animals sounds; warnings such as predators lurking near sounded off from one animal can actually warn other animals who recognize their language.