Three hundred and sixty-four babies in 365 days.
That's what happened when zoologists bred the first three Syrian hamsters living in captivity in 1930. All domestic golden hamsters available today are descendants from that original trio, researchers believe, and as such are testimony to the hamster's incredible breeding power. With their frequent “heat” cycles and short gestation periods, hamsters can add numbers to their species census even faster than other rodents known for their reproductive prowess, such as rats and mice.
One good thing about owning hamsters is that you're unlikely to have any unwanted pregnancies. Hamsters are not social creatures, and adults must be kept alone in their cages. The possibility of accidental breeding is thus eliminated, and you must carefully and purposefully choreograph the introduction of intended mates.
Hamsters are sexually mature by 5 weeks of age, but a 4-month-old female will make a more successful parent. All female golden hamsters have an estrous cycle of 4 days, which means that every 4 days there is a 6- to 10-hour window of opportunity for you to introduce her to a potential beau. Female hamsters are intensely territorial and will attack any males that approach them at other times. They are larger and more aggressive than male hamsters, and if a mismatched pair is allowed to fight it out to the end, the female almost always wins.
Setting the Scene
With this in mind, introduce your female to a male on his home turf or in a neutral zone. Some breeders recommend that you place the two hamsters' cages next to each other for a few days before you attempt to breed them. Side by side, the hamsters have a chance to get used to each other's scent before you put the female in the male's cage. Other breeders think you should place the two hamsters in a third cage that is not familiar territory for either of them. If you choose this method, put the male in the cage first and let him calm down and explore before you add the female. Either way, keep a pair of gloves on hand so you can separate the two if they start to fight.
Hamsters are nocturnal animals, so wait until evening to introduce your hamsters. If the female is receptive to the male's advances, they will mate almost immediately. The female will freeze in a ready position, tiny tail pointed to the sky, and the male will approach her rapidly. If the timing is wrong, the hamsters will fight instead, and you should remove the female right away. Try again the next night, and the next, until they mate. The male and female should be separated 20 minutes after they mate or whenever they lose interest in sex and start fighting. Then move the female to a hard-bottomed cage (a 10-gallon aquarium is ideal) to prepare for giving birth.
If possible, provide your hamster with a 6-inch by 6-inch nesting box. Make sure she has lots of bedding, like newspaper or cotton cloth to work with, but avoid “fluffy” beddings like the cotton-wool beddings offered at some pet stores. Even though this bedding is labeled safe, it can be dangerous for your hamster if consumed.
Increase the amount of apples and other fresh fruit that you give her and try to make sure that protein-rich foods make up at least a quarter of her diet. Your hamster will be noticeably larger by the 10th day of her pregnancy; her body weight may double before she gives birth. Clean her cage for the last time 2 weeks after copulation and try to stay out of your hamster's way. She will be very, very testy.
The hamster's gestation period is one of the shortest of all mammals: 16 days. Your hamster will be active right up to the moment she gives birth and may even run around the cage between contractions. If she deposits her pups in different locations around the cage she will collect them in her mouth and carry them over to the nest after she has given birth to the whole litter. She may give birth to as many as 16 pups, though the average litter is only around seven.
The babies are born hairless with closed eyes and weigh only about 2 ounces. Although you may be curious, you must not disturb the mother and her pups for at least a week. Cannibalism is not uncommon for hamsters, and stress may drive the mother hamster to eat some or all of her babies if they are disturbed. Do not even clean the cage during this period of time; just make sure that the mother has enough of her regular food and water and some milk-soaked bread crusts (supplied fresh daily) available to her at all times.
In one week the pups will be experimenting with solid food and by 10 days they will be wandering outside the nest. By 3 weeks the pups should be weaned and must be removed from their mother's cage. She will not go into estrous again until they have left her. Place the young in single-sex cages until they are 6 weeks old, when they should be transferred to individual cage units.