If an exercise wheel sits in a forest, will mice run on it?

Every once in a while, science asks a simple question and gets a straightforward answer.

In this case, yes, they will. And not only mice, but also rats, shrews, frogs and slugs.

True, the frogs did not exactly run, and the slugs probably ended up on the wheel by accident, but the mice clearly enjoyed it. That, scientists said, means that wheel-running is not a neurotic behavior found only in caged mice.

They like the wheel.

Two researchers in the Netherlands did an experiment that it seems nobody had tried before. They placed exercise wheels outdoors in a yard and in an area of dunes, and monitored the wheels with motion detectors and automatic cameras.

They were inspired by questions from animal welfare committees at universities about whether mice were really enjoying wheel-running, an activity used in all sorts of studies, or were instead like bears pacing in a cage, stressed and neurotic. Would they run on a wheel if they were free?