Dwarf hamsters are very social hamsters and like to live in groups. Campbell’s seem to do best in large colonies and I had 6 living quite happily in one huge tub. Winter whites tend to do best in pairs, and Roborovskis seem to be a little fussier about who they live with. Whenever you have hamsters living together its best to look out for signs of fighting. There may well be many a mild fight of dominance that signifies nothing, or there could be serous fighting going on while you sleep so it’s best to check the hamster over.
If there are signs of blood then it’s best to separate the animals, if there is obvious aggressors in a large group remove them first. Winter whites can be very vocal, as can Campbell’s so squeaking does not always mean that they are fighting, in fact I have observed one of my winter whites sat in a corner alone squeaking at its partner for no obvious reason. It simply wished to squeak. If the squeaking changes pitch them it could signify things have turned violent so it’s a good idea to keep an eye open.
Dwarfs should be introduced to each other as young as possible, once they get older its harder to pair them up, for this reason I currently have 4 Roborovski hamsters living individually. when hamster live in groups its also best to provide multiples of everything, depending on the group size, by having two or three wheels, food bowls, water bottles, you cut down the number of things they can fight over. Though I still observe 4 Campbell’s trying to run in the same wheel while the others go unused. Personally I find food best spread out rather than in bowls when dealing with more than one hamster, this prevents fighting as they can all get to some, plus they seem to enjoy rooting around for it.
Never mix the different types of hamster together, they are all different and will get confused by how the other reacts. Though Campbell’s and winter whites are very similar do not keep them together or breed them together. It can produce horrifying results.
Syrian hamsters are very solitary creatures and MUST be kept alone, if you feel your Syrian is lonely then play with it more, you are its company it will kill any other creature you put in with it. When two Syrians meet they will fight, you will be lucky if both are only injured.