The tufts of hair on the Geoffrey’s marmoset and the cotton-top tamarin aren’t just for decoration—the animals can use them to signal emotion to other members of the group. In addition to visual signaling, marmosets and tamarins also communicate via calls and olfactory signals. Groups often mark their scents on trees and branches to indicate their territories.


Geoffrey’s marmoset


Goeldi’s monkey


Pied Tamarin


From the ear tufts of the Geoffrey’s marmoset to the pompadour of the cotton-top tamarin, marmosets and tamarins are some of the most striking primates. Both groups fall under the New World monkey classification, meaning they live in Central and South America and are generally smaller and spend more time living in trees than their Old World counterparts in Africa and Asia.

Their diet reflects this arboreal lifestyle. Tamarins subsist on fruit, flowers, insects and small animals found among the branches, while marmosets are also specialized gum-eaters, with teeth adapted to prying up bark to reach the sap and gum beneath.
Social groups consist of a breeding female, one to three breeding males and offspring, which are born once or twice annually in the form of nonidentical twins. Only the Goeldi’s monkey, a group offshoot belonging to the same Callitrichinae subfamily, produces single offspring.

All species practice a unique form of cooperative rearing. Males begin to serve as primary caretakers when the infants are very young; they carry the offspring, which the female receives only for feeding. This expanded parental role may stem from the effort expended in childbirth—offspring range from 9 to 25 percent of the mother’s weight.
Amazingly, in some species fertility is controlled chemically. As a safeguard against inbreeding, the dominant female releases pheromones that prevent young females within the group from entering their reproductive cycle; they help rear their siblings instead of breeding themselves.

Scientists believe that these animals were once larger and have evolved into a smaller form as an adaptation to an insect diet. Evidence of this shift can be seen in their claws, which are actually modified versions of the nails seen in more advanced primates, as well as their propensity for twin births. As these species grew smaller and the ratio of birth weight to mother’s weight increased, it became advantageous for females to give birth to two smaller twins rather than a single larger offspring.

Many of the tamarins and marmosets at Lincoln Park Zoo can be seen in mixed-species displays reflecting the diversity of their rain forest habitats. At Regenstein Small Mammal-Reptile House, the cotton-top tamarins share space with the Hoffman’s two-toed sloth and two species of turtles, while at the Helen Brach Primate House, the Goeldi’s monkeys and the pied tamarins live with a variety of fellow New World monkeys.

Despite their visual appeal, many of these animals are increasingly hard to spot in their native habitats. Lincoln Park Zoo participates in captive- breeding programs for these severely endangered primates, with Primate Area Supervisor Andy Henderson serving on the steering committee of the New World Monkey Taxon Advisory Group, which oversees management of these species. With careful planning, zoo officials hope that even the most endangered Amazonian primate, the pied tamarin, can be restored to healthy numbers.