Hamsters, as a rule, are very territorial creatures, with some being far more aggressive to other hamsters than others. Syrian hamsters are a good example - never ever put two Syrian hamsters in a cage together unless you want to scoop out a dead hamster the next morning. Dwarf hamsters can be housed together, but it's a good idea to know how hamsters behave when interacting with each other so you can identify the warning signs of things possibly taking a turn for the worse.

Hamsters rely a great deal on body language to convey information or messages to other hamsters. Just as you or I would read hand wringing as a sign of nervousness or foot tapping as a sign of restlessness, hamsters read subtle body messages as signs of anger, anxiety, or pleasure from the actions of other hamsters.

Hamsters that have never met before can identify each other and their sex by sniffing a scent gland located just behind the ear. Hamsters that are related to each other take far less time to identify each other than they do strange hamsters, thus lending evidence to the theory that each hamster has a unique identifying scent. When two male hamsters meet and sniff, the subordinate hamster will turn and leave, while a female hamster in heat will, upon meeting and sniffing a male, turn and present her rear to the lucky male.

Being fiercely territorial creatures, hamsters spend a lot of time measuring each other up to see which is the dominant animal. They do so by sniffing another scent gland located at their midsection, forming a 'T', with each hamster taking turns sniffing. The subordinate hamster sometimes ends up on his rear legs due to aggressive sniffing on the part of the dominant hamster. If this occurs then the dominant hamster may seize the opportunity to do some damage by biting at the exposed stomach of the subordinate hamster. The attacked hamster at this point has two choices - surrender or fight.

If the subordinate hamster doesn't feel like testing his luck he can indicate his surrender by holding out one of his paws in front of him and avoiding eye contact. If this doesn't work then the two hamsters will enter the first phase of combat, called rolling fighting. This is basically some intense wrestling with a few bites at the midsection for good measure. A hamster can admit defeat at this point by rolling over on his back. However any fighting that continues past this point becomes very serious.

Any hamsters still fighting at this point are in it to do some serious damage to each other. In the wild a beaten hamster can attempt to flee, but in a confined space such as a cage the hamsters will fight until one has torn the other to shreds. Attempting to pull them apart with your bare hands will get you nothing other than badly bitten fingers - your best bet at this point would be to spray the hamsters with a water bottle and separate them while they're recovering from the soaking. Wear gloves or else you could still receive a nasty bite.