Use of Iodine-131 To Measure Movements of Small Animals

Abstract
A technique utilizing iodine-131 was developed to study the movements of Microtus pennsylvanicus in the field. Iodine-131 (½ mc) was placed in a polyethylene capsule and inserted beneath the animal's skin. Movements of the animal were then followed for periods of up to 2 weeks by means of a Geiger-Müller counter attached to an aluminum pole.