I’m pretty convinced that I’m dealing with a male and female here. When I was cleaning their tank out today I had them both in the plastic carrier and I noticed the larger one with the sore on is nose trying to sniff under the bum of the other.
I later scruffed them both again and the larger one clearly had a bit of a round shape to the end of his bum and its easy to see where his testicles are. He’s also has a small yellowish spot on his belly. I’m not sure how well you should see the scent glad but I believe this yellow patch of fur is where it is. On my gerbils they are larger and I can clearly see the scent glands when they stand up. Both Roborovskis are like an inch long though.
I scruffed the smaller one and there is no sign of what looks like testicles and I didn’t notice any gland either. I bought them both at the same time when they were both the same size so I’m assuming the same age, but now that I've had them a while I can really see a difference in their size.
Poop
I guess I'll have to separate them if I don’t want inbreeding, they are most likely related. If I add a mesh partition will they still feel as though they are living in a colony despite the fact they can't physically interact?