Roborovski Dwarfs

Question
Hello!

I purchased 3 baby Robo's from my local pet shop 4 days ago. They we sexed as all females. They are approx 7 weeks old. They are from good parents as we watched the babies since birth in the shop.
On bringing them home, they settled into their new home fine, enjoying the wheel, tubes and wooden playground. however, on their 2nd day we noticed they had began fighting. After some research i found it was just playfighting so left them to it yet still observing. The next day it carried on and we noticed blood on one of the hamsters nose and squeaking.
So we conducted some tests to see which hamster was starting the fight. After pairing them off we found it was Doris, who is slightly bigger than the other 2, Daisy and Daffy.
Doris was being very dominant of the food bowl and chasing the others to stay away. So we have separated her from Daisy and Daffy. Daisy and Daffy still fight but its definatly playfighting.
However, we have noticed Doris is still very jumpy and weary of her food, even in her own house and she has built a massive nest. Being much bigger than her sisters and all these other things, could it be that Doris is pregnant?? SHe was kept in a mixed sex group at the pet shop.

Sorry this is so long but I thought it is important for you to know as much as I can tell you as I really want to know that I am doing best by Doris keeping her separated.

Thanks

Steph and Bob

Answer
Dear Steph and Bob,

This is a case that almost everyone I know, with hamsters has come across (fighting and "Is she pregnant?").First of all, thank you for seperating them, that was the right thing to do, and yet it is rarely done. Hoarding is a natural behavior that most small animals take part in, especially dwarf hamsters! This is nothing to be too worried about, but the fattness does bother me a little bit... Females become able to reproduce at the age of six to seven weeks old. It is very possible that she is pregnant. If she is, over the next 10 to 18 days she will grow fatter, and more hostile to other hamsters, and to you. In the event that she does have babies, leave her alone while its happening, and dont change the cage before or after it happens(She will get hostile, and eat her babies).
Keep an eye on Daisy and Daffy though, playful fighting easily turns into fatal sparring. My personal opinion is that hamsters living together is easier said than done!
I hope this information was of assistance to you, please e-mail me back if I have failed to answer any part of your question!
Sincerely,
Sarah