Mating:
Gerbils will mate for several hours, in frequent short bursts followed by short chases where the female allows the male to catch her. Once he catches her, the female will squeak and make flick motions to get the male off of her. Males will not attack females except in rare circumstances which may also include them having been separated from their original mates, or widowed. A female may attack a male, but usually he is more than a match for her.
Raising Young:
Baby stages
When first born, gerbil babies are blind, deaf, hairless, and helpless. They drink their mother's milk. The young squeak softly when feeding and being picked up. Eventually they grow bigger, and within a week, they will begin to show skin pigment, indicating their possible fur color and markings. Soon after this, a thin downy fur will grow on them, and they will begin to make their fast yet unsteady way out of the nest when the bed is disturbed. This survival technique helps the babies get out of harm's way in case of a territory invasion.
The fur will grow thicker and longer, and by three weeks some of them may have one of their eyes open. Around this point, they begin to be weaned, eating food and not relying so much on milk. At this point, it would help to provide a soft food like an oat and milk mixture for them. The gerbils will become more active and their tails will lengthen and give them more balance so they can stand upright. When fully weaned and beginning to play fight with one another, they will soon be ready to move away, if required.
A mother will often be stern with how quickly the babies are weaned if she is expecting a new litter. A less fertile mother may let her litter suckle for longer. Older mothers often do not have as good a milk supply, and need plentiful water available to replenish it.
A litter will be of about 4-8 gerbils on average, although losses due to runts, defects and infanticide, or occasional, unexplainable persecution from other gerbils sometimes make the eventual litter one or two short.
Reproducing:
The most common ways of checking the sex of a young gerbil are: 1) Turning the gerbil over and checking the gap size between the genital organs of the gerbil. Female gerbils have a small gap between the two areas, while males have a much larger gap. 2) Although not always clear in childhood and adolescence, male gerbils have a fur covered bulge at the base of their tails, on their underside. This is their scrotal pouch. Females have smooth, round back ends.
Males are generally larger than females in adulthood, in length, height, and width. A gerbil can also be sexed by looking at its underside when it is a blind, deaf baby. There will be either a thick line in the middle of the stomach (the scent marker) if it is a male, or eight dots (four on the left side, four on the right) (soon to be teats) if it is a female.