Giant pandas do not communicate the way other animals do. A panda's face cannot display facial expressions. With no crest or mane, there is nothing to stand upright. Ears aren't tall enough to cock forward, and tails are too stubby. Because of these limitations, pandas are forced to communicate using other methods such as scent marking.
The giant panda creates a secretion from the anal glands and then rubs this onto tree trunks and rocks. This secretion is a dark, thick and sticky substance which can't be removed without a lot of hard work. A panda will leave a mark to advertise she is in heat and ready to reproduce or to mark territory. Another panda can tell a lot from a scent mark, including the gender, age, mood and reproductive status. A panda will use a variety of positions to scent mark, this includes a head stand, leg cock, or squatting.
In addition to scent marking, giant pandas also communicate vocally. They have up to 11 different sounds. In order to intimidate another panda, they will make a barking sound. During the reproductive season, a mating pair will produce a goat-like bleating sound. Other sounds that have been witnessed include, bleating and honking, huffing, barking, and growling sounds.