Before deciding to breed, it is important to consider what you are going to do with the young. A pair of gerbils will produce some where in the region of 50 babies during their reproductive life time. It is very easy to become over run with baby gerbils needing homes.
Gerbils become sexually mature at about four months of age. If you pair up an adult with a younger female, then you may find that she becomes sexually mature slightly younger. Females tend to come into season in the early evening and mating is a noisy and prolonged affair with much drumming of feet, chasing around, and the male repeatedly mating with the female.
Pregnancy usually lasts between 21 – 25 days and then the mother will give birth. Gerbils hide their pregnancies well and there is often no sign that she is pregnant, although in the last two or three days her belly may appear slightly swollen. Her behaviour may also change, with the male being made unwelcome in the nest shortly before the birth. Gerbil mothers need no help giving birth, and usually the first sign of the arrival of the litter is the squeaking noise the pups make.
An important fact to consider is that like many other rodents, gerbils will mate the same day they give birth. However, whilst nursing her pups the implantation of the embryos is delayed so the second litter will usually appear between 28 and 43 days after the birth of the first litter.
Gerbils normally give birth to five or six young, but can have anything from three to nine. Unfortunately, in the rare cases where the female only has one or two babies there may not be enough stimulus of the mother to raise them and they may die after a day or two. If you have another breeding pair, then it is possible to foster the babies and this can be very successful and can also be done with different species including rats and mice.
You may notice that the mother often appears to mistreat the pups. She will move them around a lot, split them into two groups, kick them around whilst digging or reshaping the nest. This is all perfectly normal behaviour and the pups are very rarely harmed.
Every now and again she will gather the pups together and feed them. If the father is also in the home he will help care for the pups and in fact plays a very active role in caring for his young. He will keep them warm and clean, and can sometimes be seen gathering them up and putting them back in the nest as they start crawling out to explore! Gerbil babies, known as pups are born totally pink, hairless, and their eyes and ears are sealed. All they can do is squeak, wriggle and suckle. They cannot regulate their own temperature and are dependent on their parents for everything including being kept warm. The pups continue to develop until finally by day 17 or 18 the eyes will open, and they will look like small gerbils. About this time they have developed teeth and will start trying to chew on cardboard, wood shavings and pieces of food. At this stage they are still completely dependent on the mother's milk.
Weaning takes place when the pups are about four weeks old. At this age they will be regularly eating solid food, particularly small seeds and will be drinking from the water bottle and will soon stop suckling.
To ensure your baby gerbils complete their social and emotional development they should not be separated from their parents until they are at least six weeks old, by which time they are fully independent. They can be kept with the parents until eight weeks old.
You do not need to worry about the babies breeding as they won’t breed at that age. In the wild, the youngsters would be encouraged to leave the burrow in search of territory of their own, unfortunately they cannot do this in captivity, so it is important to remove the youngsters from their parents before any conflict can occur.