Red-tailed monkeys communicate using different methods which are characteristic of communicating specific behaviors or things. Physical and vocal communication are used between members of social groups of these monkeys to demonstrate social dominance, submissiveness, or greeting. Red-tailed monkeys practice staring or staring with their mouth open. When these monkeys implement staring, they lift their eyebrows to retract the skin on their forehead which makes the skin on the face expand backwards revealing the underneath of their eyelids. Red-tailed monkeys are primarily fructivorous, but are considered omnivorous because they will eat leaves, flowers, or insects in times where fruit is scarce.