Pits versus patterns: effects of transponders on recapture rate and body condition of Danube crested newts (Triturus Dobrogicus) and common spadefoot toads (Pelobates Fuscus)

Abstract

During a long-terrn study (1987-1996) near Vienna (Austria), individual Danube crested newts (Trititrus dobrogicus) and cornmon spadefoot toads (Pelobates fuscus) were registered by photographs of highly variable Skin patterns, and the implantation of Passive lntegrated Transponders (PIT tags). To test for potential detrirnental efficts of the electronic tags, we cornpared within-year (for P. fiiscus) and between-year (for T. dobrogiczts) recapture rates and body condition index (CI) of individuals rnarked with the two altcrnative techniques. No significant negative effects of PIT tags on CI and recapture rate could be dernonstrated for either spccies. There was a decrease in body condition and recapture rates in the study years 1995 and 1996, but can be attributed to population trends rather than to the different rnarking rnethods. For recaptured T ~iobrogicusa 10.5% loss of PIT tags was observed