Look at the picture below to see the difference between a male or a female. They can be sexed by examining the genitalia.
The usual inter-birth interval is about 151-156 days. The gestation is varying between 140-146 days. A few weeks before giving birth your female marmoset typically becomes less active.
Do not disturb them while giving birth. Normally this takes place at night. Labor typically takes about one hour. Labor being calculated from the time contractions were first visible to the first young. The interval between infants usually is 2-5 minutes. The afterbirth normally follows 10-30 minutes after the birth of the last young, and is eaten by the female and other group members. When labor takes to long, get some advice from your vet (caesarian can save the female).
They usually give birth to twins. Sometimes 1 or 3 monkeys are born. When you have 3 babies, generally one of the three dies within the week of birth. It may be necessary to hand-rear one of the three. Don’t underestimate it, HAND-REARING is not an easy job !
All members of the family carry the infants. From time to time they pass the babies back to their mother for suckling. The male will typically carry the babies around up until it is feeding time.
After 30 days the babies start to take some food.
When the babies are 40 days old, they can survive on solid food and milk substitutes.
Normally suckling takes about 100 days.
At the age of 6 months, the marmosets can be fully weaned as the breeding female has often given birth again and the subadults start to learn the rearing process to themselves.
After 15 to 18 months marmosets can breed.
Marmosets can live 7-20 years in captivity.