Hamsters instinctively exercise, and that's one reason why yours may run in circles. He needs ample cardiovascular activity on a daily basis, and he gets it on a wheel or by making hamster laps. But if yours runs in little circles seemingly obsessively, or expresses similar or otherwise erratic repetitive movements, he may be suffering from something. Emotional distress, stroke and physical illness motivate such behavior, so pay careful attention to your hamster's patterns and consult your vet.
Hamsters need daily exercise, and plenty of it. They may be small, but these creatures were designed to do a lot of traveling so they could scavenge long-distance in the wild. Hamsters can run up to 5 miles in a single night. Without a wheel to run on, yours may be left racing around his cage. Some hamsters ignore a wheel and run around the cage anyway. No hamster habitat is complete without an exercise wheel, whether he wants one or not. Your little guy needs to blow off steam and get in his daily cardio.
Your hamster is good at entertaining himself most of the time, especially if you give him distractions in his cage, such as the exercise wheel, a few climbing toys and some assorted things to chew on. That doesn't mean your hamster doesn't need your personal attention on a daily basis. Socialize him, and let him out of his cage at least once a day so he can spend time with you and get some real interaction. He won't initially be eager to jump in your hand, but tempting him with a treat on your palm daily and gently stroking him teaches him you aren't a threat. Once he is hand-trained and comfortable being handled by you, let him out for about 15 minutes of playtime per day. If you don't let him out enough, he could get restless and run around the cage obsessively.
Illness could be behind a hamster's circular running. For example, a hamster that has a stroke could start running in circles -- elderly hamsters are especially prone to this. Hamsters that live in environments that are too warm may be susceptible to strokes. Running in little circles for longer than a few seconds is a symptom of stroke for this animal. Meanwhile, besides stroke, conditions that can motivate the same circular-running behavior include infection, a vertigolike condition and other illnesses. If your hamster inexplicably runs in circles or even just constantly tilts his head, get him to a veterinarian, stat.
Female hamsters go into heat every four days. When they do, they can become a little antsy. A hamster in heat may behave erratically when she doesn't have a mate, doing things like biting the bars of her cage more than usual, racing around in circles or even biting you. Unless you want lots of baby hamsters running around, you're best off just ignoring this behavior.
- hamster in ball on table image by cat from Fotolia.com