Male and female chinchillas look pretty similar, even when fully grown, mainly because the males don’t have the obvious genitalia of, for example, rats. Because they can breed prolifically and because you should keep them in single-gender pairs, not alone, determining gender is crucial. Although you can probably make a good guess if you examine your pets carefully, ask your vet for confirmation to be on the safe side.
Examining Your Chinchillas
Using both hands, lift the chinchilla onto your lap and position him upside down or upright with his rump supported. Ask somebody to help if the chinchilla is prone to wriggling. You want to view his or her genital area, located on the underside near the tail—you might need to gently part the fur with your fingers to see it properly. As soon as you’ve had a look, place the chinchilla back on the ground. Often they don’t like being held or manipulated for long.
In the genital area you’ll see two small openings. The one nearer the tail is the anus and the other one is either the vagina or the penis slot. In females the two openings are very close together, almost touching, whereas males have a distinct gap. This is the only clearly visible difference between the sexes.
When to Separate
If you adopted a pregnant female chinchilla, it’s crucial to sex and separate the babies once they reach about 3 months of age. Males become fertile from 4 months onward, females a little later, and chinchillas have no strong objections to incest. The female kits can stay with their mother, but you must transfer the males to new housing.
Female chinchillas tend to be slightly more active than males, although individual personalities vary enormously. They are also more sociable towards strangers. It is possible to introduce two adult female chinchillas to each other, provided you are patient, but adult males may not take at all kindly to a strange face. They’ll get on with the littermates they grew up with, but you may never be able to keep two unrelated adult males together.
Judith Willson has been writing since 2009, specializing in environmental and scientific topics. She has written content for school websites and worked for a Glasgow newspaper. Willson has a Master of Arts in English from the University of Aberdeen, Scotland.