Guinea pigs

Question
I have two guinea pigs(i think they are females but not totally sure).There has been tension between them since i got them a year ago.They are not from the same litter, because one is a crested and one is a american.The (bigger) crested one is "bullying" the smaller one,she is chancing her around the cage, and biting her ears,not letting her eat, and making a gurgling noise and her hair stands up.I do not know what to do!Should i separate them,one person said i should rub them with a towel to get the sent off?
         Please HELP!!!
         Thanks,
         Gabe

Answer
At a year old it should be quite obvious if one or both of them are males. They are fully developed and the testicles would be very obvious.  If they are both females it's not unusual for one to bully the other.

In any herd (and guinea pigs are herding animals) there is always an alpha and an omega. Alpha is always the boss and the omega, which means last, will always be subservient to the Alpha. You don't mention if this is a continual behavior or if it is happening in cycles. If it is continuous you may wish to separate them.

If it seems to run in cycles, like every two or three weeks and lasts for just a few days it may be that the bully is in heat and is just generally being bitchy, as many of them do. If there is no obvious injury, bleeding or torn ears it is probably just the Alpha female showing off.

If however, you do see that the smaller pig is not being allowed to eat I would most definitely separate them for the sake of her health. That gurgling, or growling noise accompanied by the hair standing up is a sure sign of serious aggression. If that's the case there will be bloodshed.

Taking a towel and trying to remove a scent is not going to be effective. The safest thing you can do at this point is just remove the danger by separating the two of them.

If they are males you should have noticed the genitalia and obvious signs of male development.  Even when raised as babies together the males become aggressive as they reach their sexual maturity and must be separated for the safety of them both.  The bottom line appears to be separate housing to keep anyone from harm.