This illustration shows you the difference between a male and a female degu. As you can see, male degus have their posterior further from the urine opening than the female degus have. That's the main sign by which you can separate them at a young age. When a male degu has grown up, there is no problem to separate him from a female. Usually, the male degus are bigger than female ones. Females grow up sexually sometimes already as small as 6 weeks old, but it can take as long as a year. It often happens that the father fecundates his daughter, so you should not keep the puppies with their parents for a very long time. Males grow up later than females sexually. Sometimes the males grow up sexually after a couple of months, but sometimes a pair of degus will not have their first litter until they are 2 years old or later. When the degus are mating, they produce a strange sound and move their tails around.
A pregnancy is recognizable in a female just one month before the childbirth. After this, do not catch her and do not try to catch the puppies in her. This can cause an abortion, and also to the death of a pregnant female. In the period of time when the pregnancy is obvious, the male degu builds upon the nest in their nest box, so you have to give them enough nesting material (paper, hay, napkins etc...). If you have more than just these two degus, the rest of them will mostly stop using the nest box. Because of this, you should prepare another nest for these.
The pregnancy period for degus is longer than that of other rodents. It is about 90 days long. The birth of a puppy does not normally take longer than 45 minutes, and some females can even give birth to five children in this amount of time. On the other hand, our female was once giving birth to a child for half a day. So the time childbirth takes varies a lot. If there are more females in the cage, they help the mother with the birth. If there are more pregnant females, they put their children into one nest and suckle them together. They don't care about which child belongs to which mother, as all the adult degus take care of all the children. Sometimes, females who bore sooner also nurse if their children are old enough not to be nursed. In our case, older babies went to a female who had younger babies and wanted to be nursed, although they were already eating normal food. Female degus have 4 pairs of teats. Nursing their children, they lay above them. A male degu is a great father - he helps out with the education of the children, takes care of them and plays with them. There is no reason to separate him from the female degu when she has babies - it is better letting them be together. The degus are different to other rodents concerning this. With hamsters, for example, you should remove the male because he could kill the babies.
Due to the long pregnancy period, newborn degus are well developed - they have fur, they can see and they have teeth. Only a few hours after their birth, they will start searching the surroundings of the nest box. Soon after this, they will also start eating normal food. Some breeders separate the young degus from their parents 3 weeks after their birth. I personally recommend you not do that before they are 5 to 6 weeks old, because it is better for them. But don't let female children be with parents any longer than this, as they can become pregnant with their father.
Watching a degu family is a beautiful experience, because they are very social animals. If you want to have young degus, buy one male degu and one or more female degus. I do not recommend keeping more than one male degus in a single cage - in the nature there is always one male who becomes the father of the whole colony. More males can fight to get this position. But think of this very carefully - degus could have up to four litters a year and they can have 8 puppies in each litter. If you have decided you want your degus to have children, remember that it would not be fair to them to separate the male from the female in the future… when you decide to stop having degu children. The male and the female degus will get attached to each other.
Another interesting fact with degus - a degu female can become pregnant within 24 hours from childbirth. If not, she can become pregnant again after a few weeks - when she stops nursing her children. So, it is recommended to separate males and females for one or two days after the childbirth to avoid another pregnancy, which could stress the female through the nursing period.