Slow-release radioisotope implants as individual markers for carnivores

Crabtree, R.L., Burton, F.G., Garland, T.R., Cataldo, D.A. and Rickard, W.H.

The Journal of Wildlife Management, Vol. 53 Issue 4 pp. 949-954


We developed a technique that identifies an individual animal by labeling its excreta. Various gamma-emitting radioisotopes were incorporated into implantable discs made of polylactic acid (PLA), a biodegradable polymer. Laboratory testing and field studies with coyotes (Canis latrans) demonstrated that the 6 radioisotopes evaluated were released from the subcutaneously-implanted polymer at a relatively constant rate after an initial burst phase and allowed a minimum marking period of 6 months. Prototype slow-release implants were used in a field study of coyotes to estimate population abundance, estimate home range, assess individual diets, and examine social and scent-marking behavior. The implant technique has potential widespread application in studies of wild carnivores.

Patrick Cross1989