One of the most important skills required when breeding gerbils, is knowing how to sex them. Gerbils have been known to breed as young as seven weeks, so it is imperative that the males and females are seperated properly.
When pups are first born it is very difficult to determine their gender. If you have a keen eye, however, you should be able to tell them apart.
Female newborns have their urethra and anus nearly touching. Male newborns have a slight space between the urethra and anus.
This difference will be more obvious if you observe them side-by-side.
Sexing 11 day-old Pups
Pups are easiest to sex at about day 11. The hair has begun to grow on the belly and this leaves little circles of bare skin around the female's nipples.
The male pup at 11 days does not have circles of bare skin present.
Sexing 5 week-old Pups
Once the hair grows completely over the nipples, it becomes very difficult to ascertain the gender of your pups until the genitalia become distinctly different.
At about 5 weeks of age, the male pup has a very distinct scrotal bulge.
The urethra and anus are far apart in male pups as well.
The female pup does not have a scrotal bulge and the urethra and anus are very
(Please ignore that the male pup is in the process of pooping)
Sexing Adult Gerbils
Adult male gerbils are similarly equipped as the 5 week old males, but the scrotal bulge is much more evident and the urethra and anus are even farther apart.
Again, adult females do not have a scrotal bulge and the urethra and anus are close together.