Sexually dimorphic means that it's fairly easy to tell the difference between male and female in a particular species by obvious visual clues. That's not the case with the chinchilla. Males and females look pretty much the same, and it takes expertise and close observation to tell which is which. They are both small rodents with dense, plush fur, big ear and bushy tails.
If you only have one chinchilla, it doesn't really matter whether it's George or Georgia, but two chinchillas can result in unwanted litters if they are male and female. Chinchillas reach sexual maturity at the age of 7 months, and give birth to one or two kits in a litter.
If you have two chinchillas together, it's likely the female will dominate the male -- she rules the roost. However, there's always the possibility that you have the same sexes in the cage.
The most effective way to determine a chinchilla's sex is by direct inspection of the genitalia. Hold the animal with the abdomen up and look at the anal area. This is what you're looking for:
- Male chinchillas have a hairless patch between their urethral opening and their anus.
- Females don't have a hairless patch, and their vagina appears as a small slit.
- Males have a greater distance between the anus and the urethral opening than do females.