Radioactive Zinc As A Feces Tag In Rabbits, Foxes, And Bobcats

The radioactive isotope, 65Zn was fed and injected into rabbits, opossums, foxes, and bobcats. When injected, 65Zn was detectable in feces from these animals for over a year after injection. The radioactive zinc present in the fecal pellets is also very stable to weathering. The injection of 65Zn is an excellent technique for long-term marking of feces in censusing, home range, and migration studies. Public health dangers, although largely imaginary, seriously limit the use of this technique and are discussed.