Because otherwise there is no need to communicate. If you don't want to communicate, why bother?
The theory of communication would have it that communication has only occurred when the recipient is aware of the message. In this sense, broadcast radio is possibly not communicating for at least...
To convey information.AND...
There aren't any naturally, but if you put some there in the in the nature, they could survive. You can also find some in zoos.
It is unknown if any animal species on earth communicat in a certain way ( like language not just nods and random noises).