Tamarins Marmosets and Goeldi's Monkey: Callitrichidae

Physical characteristics: Goeldi's monkeys have long, silky, brownish black fur, with a mane of hair covering the neck and shoulders and longer hairs on the rump. They weigh about 1.1 pounds (500 grams) and measure 8 to 9 inches (20 to 23 centimeters), with a tail length of 10 to 12 inches (25 to 30 centimeters). Unlike other callitrichids, they have thirty-six teeth instead of thirty-two, due to an extra molar on both sides of the jaws. The long tail is used for balance in traveling through the trees. They have claws, except for the large toes that have flat nails.

The Goeldi's monkey's diet consists predominantly of fruits and insects. (Norman Owen Tomalin/Bruce Coleman Inc. Reproduced by permission.)

Geographic range: Goeldi's monkeys are found in Bolivia, Brazil, Colombia, Ecuador, and Peru.

Habitat: Goeldi's monkeys prefer secondary forests with less-developed canopy and dense bamboo grasses and shrubs. They also inhabit deciduous scrub forests.

Diet: The Goeldi's monkey's diet consists predominantly of fruits and insects. It also eats tree frogs and occasionally forages for grasshoppers, crickets, and cockroaches on the forest floor.

Behavior and reproduction: Goeldi's monkeys live in groups of two to nine individuals, made up of one to three adult males and females. During the day they travel through the forest by vertical clinging and leaping, instead of on their four feet. They communicate through a variety of vocalizations, including trills for warning signals and whistles for long-distance calls.

Each group has two breeding females, who may give birth twice a year. Unlike tamarins and marmosets who give birth to twins, Goeldi's monkeys give birth to a single young. The mother alone takes care of the newborn for almost three weeks, after which the father and other family members share in parenting. The infant is carried on the back. However, when escaping predators, animals that hunt them for food, the monkeys do not take their young with them, but hide them among vegetation. They themselves hide in the lower shrubbery. Infants become independent by the eighth week.

Goeldi's monkeys and people: Goeldi's monkeys are trapped for the pet trade.

Conservation status: The IUCN lists Goeldi's monkey as Near Threatened, meaning they are not currently threatened, but could become so, due to habitat loss and degradation from human settlements and logging. It is classified as vulnerable in Colombia because of limited populations. ∎