The fur of the Common Marmoset is grey. The most distinguishing characteristic is the white tufts of hair which surround the ears, which lend it another common name, the Cotton Eared Marmoset. A white mark is on the forehead and the face is hairless. The long tail is grey-white. Common Marmoset adult size ranges from 14 to 18 cm and they weigh approximately 400 g or 14ounces. The diet of the Common Marmoset consists of insects, spiders, small vertebrates, bird eggs and tree sap. They spend 25-30% of their time budget searching for food. Common Marmosets live together in family groups of four to 15 animals, usually mated adults and their offspring. These groups inhabit territories of 300,000 square metres. The groups have a strict ranking, ordered by the dominance and aggressive behavior of the group leader.