For the giant panda population, the visible signals are meaningless to them: their round faces lack expression, their tails are short, they do not have a crown or brown hair to spread out, and their ears can be raised and lowered, but they are not flexible enough. This is all because giant pandas live year-round in dense, misty bamboo forests on high mountains, unable to see each other.
Most communication among giant pandas is achieved through scent markers left in their habitats. When they want to meet, usually during estrus season, they will find each other through scent markers. Once they meet, it turns into sound communication. Giant pandas rely on their rich 'language' to express emotions ranging from sentimentality to anger.
Silence is another way of communication. When giant pandas are playing or simply expressing friendliness, without mating or aggressive thoughts, they will not make any sound. This sound rule can help you determine the behavior of most pandas you see in the zoo.
Marking territory with scent is the secret for giant pandas to maintain peace in bamboo forests. Giant pandas apply secretions from their perianal glands to pillars, tree stumps, walls, floors, and areas they frequently pass through. These odor markers can help them avoid each other or gather together. During non estrous seasons, when they smell unfamiliar pandas, they will walk away. During the estrous season, the scent of a female giant panda may indicate that she is ready to mate and hopes to attract males.
Giant pandas have several ways of marking. They often use urine, or a mixture of urine and perianal gland secretions, for labeling. When they make marks, they shake their heads and their mouths are half open. After marking, they will peel off the bark or leave scratches at the marked area to attract the attention of other giant pandas.