Inexpensive Motion Detectors for Quantification of Animal Activity

Measurement of locomotor activity of captive animals is important in such fields as chronobiology, physiology, animal behavior and ecology. Because running wheels are convenient and can be made inexpensively, they are the most commonly used device to quantify activity, particularly in studies of rodents. However, wheel running is unnatural behavior, and activity measurements do not necessarily correlate with activity in large enclosures or in natural environments. Tilt floors and treadles also can be used to quantify activity, but these too provide sensory feedback to the subjects and may alter behavior. In summary, the design described here avoids the disadvantages of running wheels and tilt floors by using a motion sensor that allows direct and continuous measurement of activity without altering the behavior of the subject. Other studies have used motion sensors in similar ways, but this design allows the use of inexpensive and readily available equipment. Minimal money and time are required to establish this system, and once established, data can be collected continuously. Limitations of this system include the requirement of a lamp in the circuit, which limits its applicability to field situations.