Tucked away in the Tropical habitat in the Marie Osterbuhr Aviary is a tiny species of monkey.

In fact, it’s the only species of monkey at Lee Richardson Zoo. Goeldi’s monkeys, also known as callimicos, are New World monkeys found primarily in the Amazon of Peru, as well as in some regions of Colombia, Bolivia, and Brazil.

Unfortunately, these countries represent four of the world’s top seven nations in terms of forest loss due to human expansion, timber harvesting, and agriculture. Less than half the forests where they are found are protected.

Since the species is so patchily distributed across its range because of its need for particular habitats and food sources, Goeldi’s monkey populations are especially sensitive to these human activities. The International Union for the Conservation of Nature (IUCN) lists the species as Vulnerable.

Due to their elusive nature, there are no good estimates of the world’s overall population, but loss of historical habitat and less frequent sightings indicate that their numbers are declining.

The other primates found at the zoo are classified as prosimians or as lesser apes. Prosimians retain ancestral traits, such as being nocturnal or having the capability to scent-mark. Lesser apes are characterized by their lack of tails and higher intelligence.

The zoo’s prosimians include the ring-tailed, black and white, and red ruffed lemurs, and the pygmy slow lorises. The lemurs are found at the zoo’s Primate Forest Lemurs!, and the slow lorises in the zoo’s nocturnal building in Wild Asia. The representative lesser apes are the white-cheeked gibbons, who also reside in Wild Asia.

Goeldi’s monkeys are unique primates in many ways. Like their close cousins, the tamarins and marmosets, Goeldi’s are very diminutive. They weigh just about a pound and are less than 10 inches in length, with a tail just as long. They move about the tropical forest much like squirrels because of their claw-like nails. This is different from larger-bodied primates.

These claws allow them to escape predators quickly and help them extract certain foods. They prefer fruits, flowers, insects and spiders, mollusks, and small vertebrates such as lizards, snakes, and frogs. Goeldi’s monkeys have a unique adaptation: they can feed on fungi to sustain themselves during dry seasons. This dietary trait is found in no other tropical primate.

Like other small New World monkeys, baby Goeldi’s are initially carried by their mother’s, but are gradually handed off to fathers and other members of a troop as the infants grow. This is especially important in marmosets and tamarins, which typically have twins or even triplets that collectively weigh 15 – 25% of the mother’s weight. Those mothers must share rearing responsibilities so they can provide for their own nutritional and energy needs while lactating.

Goeldi’s monkeys, however, give birth to a single infant who weighs just about 10% of the mother’s weight. This allows mothers to carry their single infants a little longer before sharing the role and to delay weaning.

With this strategy of concentrated effort, Goeldi’s monkeys grow faster and become independent much earlier than others. By four weeks, Goeldi’s infants can be seen begging or robbing food from others who readily provide it to them. By three months of age, they are rarely carried at all.

On your next visit to the zoo, don’t mistake our pair of Goeldi’s monkeys, “Peach” and “JB,” as baby monkeys. They’re fully grown and among the world’s most unique primates.

To learn more about what’s happening at the Zoo, visit www.leerichardsonzoo.org or the Zoo’s social media pages. The zoo is currently open daily 10 a.m. to 5 p.m. with drive-through access from 10 a.m. until 4 p.m.