The Common marmosets are unique primates with a rather unusual appearance and a number of special adaptations. The New World monkeys exhibit a gray overall coloration. Their gray considerably long tails are covered with white and gray stripes. As they age, the animals grow white colored tufts that begin from both sides of their face. The claw-like nails on their feet (known as tegulae) make these primates excellent clingers and leapers. The large intestine allows them to consume large amounts of food. Additionally, these animals have specialized incisors.
The Common marmosets are found in Brazil; more precisely, from the northeastern coast westwards to the Rio Grande as well as in the southern parts of the country. These primates live in a wide variety of forests, including undisturbed primary forests, riverine forests, scrubland (usually, in more open areas), regenerating young forests as well as orchards and gardens. Some introduced populations may occur in Rio de Janeiro, Buenos Aires and other cities. Overall, the ideal habitat for this species is young growth with dense vegetation, dominated by creepers and vines.
The Common marmosets are highly social creatures, forming family units of 3 - 12 individuals, consisting of a breeding pair and their multiple young. Mates usually don't tolerate rivals for the attention of their mate. These primates are highly territorial animals, marking their home ranges by rubbing scent, found in their scrotal glands, onto tree branches. They lead diurnal lifestyle, being active during the daytime hours. These animals use tree holes and cavities as shelters and rely on excellent eyesight, hearing and smell to perceive their environment. They have a rather diverse communication system. For example, emotions are displayed through movements of the eyelids and ears as well as hairy adornments of the head. As it comes to vocalizations, these primates are known to use “gee-gee-gee” noises and different high-pitched chirps, resembling these emitted by birds. They accompany these calls with various facial expressions. Additionally, they produce a short “uistiti-uistiti” sound, which serves as mating call.
The Common marmosets are predominantly herbivores. The diet of these primates is mainly composed of tree sap, supplemented with various insects, spiders, fruit, flowers and nectar. On occasion, the Common marmosets are also known to consume frogs, small lizards as well as eggs and chicks of some birds.
The Common marmosets were formerly believed to have a monogamous mating system (where each individual has only one mate), based on the fact that captive individuals of this species tend to form long-lasting, monogamous pairs. Nevertheless, a recent study revealed that these primates in the wild practice polyandry, which means that each female breeds with numerous males. They are known to form breeding groups of 2 males and a single female. Gestation period lasts for 142 - 150 days, yielding 1 - 3 infants with an average of 2 per litter. Newborn babies grow up very quickly. At 4 - 5 weeks old, they are ready to take solid food. Young marmosets are weaned at 3 months old and enter the juvenile phase at about 5 months old. They are sub-adults at 9 - 14 months old, soon gaining their sexual maturity. They usually gain their adult size at 15 months old, at which point young marmosets are mature and ready to mate. However, mating doesn't occur, until they are able to establish dominance.
The Common marmosets are primarily threatened by continuous loss and destruction of their natural habitat, despite the wide distribution and large number of their population as well as the fact that these animals may often replace other Callithrix species in areas, where they have been introduced. Additionally, the Common marmosets are sometimes captured as a pet species.
According to IUCN, the Common marmoset is common and widely distributed throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) and its numbers remain stable.