Reproduction Saguinus geoffroyi has a polyandrous mating system, that is, many males mate with only one female. The mating season occurs during January and February, and the births take place from March through June, with the majority occurring from late April to early June. The gestation period usually lasts from 140 to 145 days. Females can have between one and two young at once, and the young usually weigh about 40 grams at birth. One breeding female usually bears twins.
Males help care for and carry the young.
Carrying the young for the first six to eight weeks of life is very important. The nursing period usually lasts about two to three months and sexual maturity is achieved at about 24 months. Behavior Saguinus geoffroyi is diurnal and is usually found in groups of 2-19 individuals. They are a territorial species that has been found to visit the border of their range and mark the trees early in the morning each day . Males usually visit the border most often.