Long-term survival and growth of free-living great crested newts (Triturus cristatus) pit-tagged at metamorphosis

Twenty-one late-larval or newly-metamorphosed great crested newts (Triturus cristatus) were implanted with passive transponders (PIT tags) and released into the wild at their natal pond, in England, in 1996. Body mass at the time of release ranged from 0.69 g to 1.57 g, excluding the tag. Eight of the tagged newts were recaptured as breeding adults in 1999 (5 males, 3 females). Seven of the eight were recaptured again in 2000 (5 males, 2 females), along with four more tagged animals(3 males, 1 female). The mean annual survival over the four years from tagging and release in 1996 to the breeding season in 2000 was at least 85%. The tagged newts recaptured in 1999 were among the smallest in the breeding population that year, which was consistent with their being the youngest; this interpretation was supported by the appearance of a new group of similar-sized newts the following year. The growth of tagged newts between 1999 and 2000 was consistent with that of the population at large. Overall, we found high mean annual survival and normal rates of growth among great crested newts PIT-tagged at metamorphosis, indicating that the tagging procedure we used was benign. This use of PIT tags, which allow long-term and instant identification of individual animals, provides a means for investigating dispersal, colonization and metapopulation dynamics during the hitherto little-studied juvenile phase of the life cycle of this protected species.