They communicate by sounds and the moon Answer.
Communication within species is usually shown through display, vocal, and olfactory ways. Through display, species use movement or showing of body parts sometimes in form of deception. Through vocals,species tend to sing, have warning, mating and territorial calls. Lastly, animals communicate through olfactory which is through means or urine, sweat, and even through rubbing trees.
Anyone who has shared his or her life with animals knows that a
special, unique unspoken language occurs. It's really our original
language, how we communicated at birth. If a feeling or a situation
was extreme, we expressed out loud in the way that we knew how, yet
the rest of the time we were quite content in this unspoken world
of energy that usually fulfilled our needs. Our parents were truly
communicating with us telepathically.
It is no different for the animals. Animals communicate with us,
and with each other in many ways. They have the ability to connect
to humans intuitively, and they also have their own body language.
They learn to respond to a few words in their species' specific
expression (barking, meowing, growling, neighing, snorting, etc.).
Domesticated animals have more of a human vocabulary than wild
animals that communicate more telepathically with pictures.
Each sound and each body movement an animal makes means something.
They express joy, fear, happiness and sadness by the way they act
and the sounds they make. Dolphins and whales, for instance, use
sonar and high-pitched whistles to speak to one another, and even
to their handlers when they are in captivity. Birds have different
songs and chirps. Cats purr, growl and hiss, dogs bark, whine and
growl, and all species have body language that is characteristic of
what they are trying to express.
You dont hear them when they communnicate they dont need to make noise or any thing they can even be looking away from each other and there still talking