Some feral animals choose to run on an exercise wheel

Researchers in the Netherlands placed a running wheel in wild settings and monitored its use.

"If wheel running is indeed caused by captive housing, wild mice are not expected to use a running wheel in nature. This however, to our knowledge, has never been tested. Here, we show that when running wheels are placed in nature, they are frequently used by wild mice, also when no extrinsic reward is provided. Bout lengths of running wheel behaviour in the wild match those for captive mice...

Over a period of over 3 years, we have analysed more than 12 000 video fragments in which wheel movement was detected, out of more than 200 000 recordings made when animals visited the recording site...

Some animals seem to use the wheel unintentionally, but mice and some shrews, rats and frogs were seen to leave the wheel and then enter it again within minutes in order to continue wheel running...

Further details at Proc Roy Soc B.