Social Structure, Reproduction, Development 

Social Structure

Live in packs or solo: Pygmy marmosets live in extended families, called troops, of up to nine monkeys but with an average of five members

Roles within the community: The father helps deliver the babies, cleans them up, and then takes over their care. He carries the newborns piggyback style for their first two weeks, bringing them back to the mother to nurse. Older siblings may help, too. When they are a bit older, the babies hide while the rest of their family looks for food until they are strong enough to travel with the group. The parents stay together for life. There are more pairs of eyes to spot predators, and everyone helps take care of the little ones. For added safety, the troop spends the night among thick vines or in a tree hole.

Male or Female led groups: In western pygmy marmosets, the troop is formed around the primary adult male and female that mate and produce young.

Individuals that make up the group: Usually the troop has a breeding pair, their babies, and any of their adult children.

How do they interact with each other: Pygmy marmosets communicate with each other by chattering and trilling in high-pitched voices. They can make sounds so high in pitch that humans can’t hear them. Certain squeaks and calls express danger or other urgent monkey messages. They also make faces to express emotions like contentment, surprise, or fear by moving their lips, eyelids, ears, and the hair around their face. 

Reproduction

How often do they mate: Pygmy marmosets breed during the female's postpartum estrus which occurs approximately 3 weeks after giving birth, producing offspring every 5 to 6 months. Breeding in pygmy marmosets does not appear to be restricted to a season.

How many mates do they have: One, the parents stay together for life.

Time of year for mating: The dominant pair breeds at any time of the year.

Mating rituals: Solitary individuals use long-distance calls when approaching troops to contact potential mates. Both male and female western pygmy marmosets use scent glands to mark trees especially to demarcate territories and communicate their readiness to mate.

Number of offspring produced at a time: Three or even four babies in one litter.

Any unique characteristics of their mating: Rather than beginning to mate when they reach puberty, young pygmy marmoset females are reproductively suppressed when they remain in their natal groups.