It isn't talking it is communication. They are signs. Like a dog will grow to tell you it's angry or bark to say it's dominating and this is it's property. A cat will meow when lonely or stressed and it will hiss if angry. A lion roars to show dominance basically saying this is my territory. Birds chirp a certain way to attract mates sometimes. or they can chirp in warning to other animals or birds. All animals have signs for their emotions but it isn't exactly talking just signals. Like for instance humans smile when they're happy and other humans will think that person is happy. The person smiling is signaling not talking. Get it?