I can see you just put this question in for a joke, but in fact we're just beginning to understand that animals do communicate in much more sophisticated ways than we realised before. It's long been realised that some animals, such as chimps, use something that we might call 'language' but we're now starting to explore communication right across the animal kingdom.
A major way for many animals to communicate is through body language. This can be very simple, like a baby gull tapping on its parent's bill to get him or her to release food; or to express emotions, like a horse putting its ears back when it is angry or nervous; or to give a clear signal like a deer stamping its hoof on the ground to warn the rest of the herd when danger approaches.
It is also now understood that many of the sounds made by different animals carry a lot of meaning, which hopefully humans can learn to read in time. You can learn more about animal languages here.