Both male and female gerbils possess a scent gland, which is a hairless, tan/skin coloured, oval patch of skin that is located in the central belly/abdominal region along the mid-ventral line of the gerbil. The male scent gland is slightly larger and he uses it more often, usually to mark his territory. A common problem with elderly gerbils is tumours of the scent gland and they most often occur in elderly males, however they are not unknown in females.  Read More about scent gland tumours in gerbils.