Soft-Release, but Not Cool Winter Temperatures, Reduces Post-Translocation Dispersal of Jewelled Geckos

Abstract

Translocations are an important conservation tool, but many are unsuccessful. Soft-release translocations involve holding animals on site for a period prior to release, whereas hard-release translocations involve immediate release of animals into a new environment. Evaluating the relative impacts of hard and soft release on site fidelity of released individuals can be informative, especially when comparing between translocated and resident animals. We monitored the movement, dispersal, and home range of both translocated (hard and soft released) and resident Jewelled Geckos (Naultinus gemmeus) for three weeks during winter using radiotelemetry. We also monitored a hard-released group during summer and incorporated data from a previously published soft- versus hard-release translocation of Jewelled Geckos undertaken in spring. In winter, soft-released geckos dispersed less than hard-released geckos and both soft-released and resident geckos had significantly smaller home ranges than those hard released. Further, area occupied by soft-released geckos remained constant during the tracking period but increased 20-fold for hard-released geckos. Mean dispersal distances were not influenced by season or the amount of time in an enclosure prior to soft release (i.e., four months yielded similar results to nine months). Translocations employing a soft-release strategy may have value for a wide range of lizard species and could contribute to translocation success.