I know there is a special ball for hamsters, which they get in start to moving in; it's called a Hamster Ball.
I want to buy one for my hamster, but I have two questions:
At what age can a hamster start to play in the ball? My hamster is about 40 days old: can he play in the ball?
How much time should he be allowed to play in the ball?
I can't answer every question, but I can tell you that in order to play in the ball the ball has to be at least six inches in diameter for dwarf hamsters and at least eight inches for Syrians to help prevent back arches.
Also, don't leave your hamster in there for too long. For starters, he might leave droppings in the ball or around the floor and even wee on the carpet. Make sure before putting your hammie in his ball that he actually wants to go. If he resists too much, this may mean he is hungry or has business to take care of. Forcing him may stress him out, as well. Keep in mind that your hamster can be in his ball for a while, but it is a good idea to take him out regularly for a drink or some food.
Do NOT give him a Hamster ball.
The Hamster cannot really control the ball, because any ball that has a size the Hamster could properly walk in (without a permanently bent spine) automatically is way too heavy for the Hamster to control.
As Alivia pointed out it will become dirty.
It is highly unnatural "ground" fro a Hamster to walk on.
And it prevent the Hamster from hiding. Hamster need hiding-places, or they will be exposed to heavy stress.
If you want to make your Hamster happy, make sure he has hiding-places, and some area he can dig in. Try to stick to natural materials (straw and wood are best). Hide food in the hamsters enclosure so it won't be bored. If you make a good place for him to live, and perhaps a good playpen, you do not need a Hamster-ball (and, actually, none of the plastic-toys :) )
PS: Due to the comment given:
I am actually going on German-Language sources, and could not find a matching English source. The German Hamster-community does mostly agree on this, so I will link to a relevant German site which basically gives a long version of what I explained. Run it through a translator for English:
No Hamster Balls - German
The German Wikipedia-Page gives the same reasons: German Wiki
PPS: It seems the English-Speaking countries are fine with Hamster-balls. I have no idea what further countries think, but the points German Animal-Protection makes seems very valid to me.
There are pros and cons about hamster balls but if you have one that is ok in size and your hamster enjoys running in them then they are fine to use but never let your hamster run in them for more than 7 minutes at a time and you should always supervise them carefully as they run around. Finally, if you decide to use the ball with your hamster, put it in a large "enclosed space" blocking off any dangerous things (like stairs).
Respecting the minimum size requirements is indeed important, and supervision as well, of course.
The Syrian hamster I had was happy in his ball for about 20 minutes at a time. At about the 30 minute point, he got tired of it, and then he and the ball didn't move around any more.
I'm a big believer in stopping an activity before it ceases to be fun. So, you have to get to know your hamster and find out what's right for him. Once you know his pattern, it will be easier to get a feel for how many minutes are fun for him or her.
It's hard to predict how long he'll be in the ball before he pees or poops. So, choose the surface carefully where you will let him run in his ball. If you don't have any bare floor, perhaps you could get a refrigerator box and cut it up, and then lay down a big piece of cardboard to protect the carpet.
After use, the ball can be washed on the inside with dish soap and warm water.
Make sure you give your hamster other types of adventures besides the ball only. For example, I made a cardboard playpen with zigzagging cardboard sections taped together. It's fun to put a nice wide cardboard tube on the floor inside the pen, put a sunflower seed inside the tube, and then watch the adventure unfold.
With a young hamster, I suggest starting out with very short trial runs. Make sure the room is warm and not drafty. Choose a time when there's not much commotion, and you'll be able to supervise.
When adopting a hamster, wait until his natural curiosity is bringing him out of his nest, showing an interest in his environment. This would take between 3 days and a week, typically (for Syrian).
