Abstract: A squirrel cage has a support including a base adapted to rest on a flat surface. The base has support arms extending upwardly from the base, and a cylinder, having an inner radius, supported by the support arms of the base for relative rotation with respect to the base when an animal, such as a hamster, runs on the inner radius of the cylinder. The cylinder has a support member having a centrally located opening for receiving the support arms of the base. A cyclometer has a sensor mounted on the support and a trigger mounted on the cylinder such that when the cylinder rotates, the trigger passes near the sensor. The trigger actuates the sensor when it passes the sensor. The sensor of the cyclometer counts the number of rotations of the cylinder when the trigger actuates the sensor. A method of the present invention monitors the activity of the animal.