The Adult Size of a Gerbil

Mature gerbils weigh between 2 and 4 ounces, with males larger than females. According to the American Gerbil Society, that's about halfway between a mouse and rat in size. Grown gerbils are about 4 inches long, not including the tail. Just as much of your gerbil consists of tail, another 4 inches, which ends in a little tuft like a lion's.

Gerbils don't like to be alone, unlike other common rodent pets like hamsters. Get a couple of gerbils, although if you don't want them to breed make sure they're sexed and confirmed beforehand. Males are larger than females. For best results, get same-sex gerbils under 2 months of age. They're not quite adult size at that point. Once a gerbil is 5 weeks old, you can see the scrotum on the male and 8 nipples on the female. If you have girls, a pair does nicely, but you can put more than two males together. If you bought your gerbils for your kids and they keep them in separate cages, make sure they play with them all separately as well. Mixing adult gerbils that didn't live together from an early age can cause rodent warfare.

Because adult gerbils are so small, a 10-gallon aquarium makes an adequate-size house for two of them, as long as it's covered by a wire mesh or another strong cover. An all-wire cage is another good choice. Keep them away from direct sunlight or drafty areas. Use aspen shavings or shredded newspaper as bedding, cleaning out the waste material daily. Provide your pets with an exercise wheel and other suitable toys. Gerbils are escape artists, so if you leave the cage uncovered or it's something they can loosen, they're gone. In addition to having fresh, clean water available 24/7, your gerbils should always have timothy hay to chew on. Feed your pets a diet specifically designed for gerbils, along with small amounts of fresh fruits and vegetables.

If you decide to breed gerbils, select only healthy, attractive specimens as the breeding pair. By the age of 13 weeks, gerbils are full size and have reached sexual maturity. The average gestation period for a pregnant gerbil is between 25 and 26 days. Most litters consisting of between four or five pups. Babies are weaned at about the age of 5 weeks, just about the time a mother, if she remained with the father during nursing, has another litter. Gerbils can have a litter once a month. You do the math.