Gerbils are very active and need physical exercise as well as mental stimulation. Good toys for gerbils include seesaws, climbing tunnels, gerbil wheels, and run-about balls; basically just about anything on which they can climb or explore.
Be sure that any exercise wheels you use are absolutely safe -- tails can easily get caught and broken or even torn off in open-wire wheels. You may wish to use special wheels designed for gerbils, or you can use a wire hamster wheel if you make some alterations. Cover the entire outside of the wheel with a heavy masking tape (sticky side on the inside of the wheel). Avoid thread-reinforced tapes such as duct tape. Cover the inner sticky surface with small amounts of bedding so the gerbil's feet will not stick to it. Alternatively, cover the outside of the wheel with thin card board or other material which will not cause harm if it is chewed and swallowed, and then apply the masking tape to securely hold it. You will routinely need to recover the wheel as the gerbil chews on whatever outside cover you have used.
HINT: Remember that you can mount the wheel on the wire cover of the cage, and let it hang down into the cage.
Run-about-balls, which provide them with much needed exercise, can be a good choice for gerbils. Allow time for adjustment. Some pets may initially be overly cautious or frightened. If your pet seems hesitant, don't force him to use the Run-About Ball. Simply place it in his cage and he'll likely investigate it and learn to use it happily. You can also place a few small treats inside for added encouragement.
Important: Run-About Balls are interactive exercise toys. Supervision is necessary. Following a few precautions, you will help your gerbil have a safe and enjoyable time. First, make sure the door of the ball locks firmly. If in doubt, use masking tape to keep it shut. Since overheating can be a potential problem, even with well-vented balls, never use in direct sunlight. Limit exercise time in the ball to 15 minutes at a time and watch for signs of overheating. Also, do not use the ball on a table or near stairways. Wash out the ball after use, so it is clean and ready the next time your gerbil is ready to play.
Tunnels and hiding
Gerbils enjoy running through tunnels, and into and out of holes. You can purchase logs with holes and tunnels drilled into them, or you can make some yourself by drilling through untreated 4x4 lumber. Gerbils chew on and destroy plastic very quickly, and may swallow small pieces, so wood and PVC pipe are the best choices for tunnels and hide-a-ways.
Gerbils originate from deserts in Mongolia. As part of their normal behavior, they take dust baths, which helps cleanse their fur. Your companion gerbil will also enjoy taking dust baths. Fill a small ceramic bowl with commercial chinchilla bath sand, and watch your gerbil have utter enjoyment.
Toys for chewing
Gerbils love to gnaw, and need to for their health, so provide them with wood on which to chew. An untreated piece of 4x4 works well. They also like to play with and chew cardboard tubes from toilet paper and paper toweling. Larger cardboard boxes can also be good toys, but like the tubes, they will not last long and you will need to replace them often. Special chew toys are also available from pet supply companies.
Toys to avoid
Do NOT give your gerbil toys made of plastic that can easily be chewed and swallowed, as this could cause intestinal blockage or irritation. Select toys that do not have any moving parts in which your gerbil could catch his tail.