there are different kinds of language, most animals can communicate with body language and they do talk to each other making sounds. no you don't have to be intelligent to communicate, otherwise some people wouldn't be able to communicate
Well, there was the man that could talk to turkeys in the United States, however during his travels to Turkey he discovered he could not communicate with the Turkish turkeys because they spoke a different dialect of turkey.
Animals can understand one another using bodily/physical movements, but most everything is just instinct, like a cry of pain, animals who hear a cry of pain will either investigate or get the heck outta there. It just depends on whether they're a hunter or prey, etc. Like a mating call, animals just KNOW what it means.
So you don't think animals are not intelligent? I can tell you for a fact coyotes are very intelligent. I can also tell you they have different howls that mean different things. I can also tell you that since I know what the different howls mean I can talk to coyotes.
Many animals communicate fairly sophisticated ideas to each other. A few, like whales, can carry on conversations. Who says they're not intelligent? Just because they don't kill each other for "sport" like we do doesn't mean we're better than they are!