PASSIVE INTEGRATED TRANSPONDERS FOR MARKING FREE-RANGING TOWNSEND GROUND-SQUIRRELS

We tested passive integrated transponders (PIT) as a technique for mar king free-ranging Spermophilus townsendii individually and permanently . We marked 1,179 squirrels with PIT tags. No known mortalities were c aused by PIT tagging, and we observed little incidence of infection at the implant site. Rates of PIT-tag loss probably were <0.05 within 1 year, with most tag loss happening shortly after tagging (less-than-or -equal-to 10 days). We detected no tag losses between 2 years. We conc lude that PIT tagging should be considered as an alternative to ear ta gging and toe clipping for marking small mammals. PIT tagging may espe cially benefit long-term demographic studies intended to estimate rate s of annual survival.