The Welfare Implications of Using Exotic Tortoises as Ecological Replacements

Christine J. Griffiths*, Nicolas Zuel, Vikash Tatayah, Carl G. Jones, Owen Griffiths, Stephen Harris

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

10 Citations (Scopus)

Abstract

Background: Ecological replacement involves the introduction of non-native species to habitats beyond their historical range, a factor identified as increasing the risk of failure for translocations. Yet the effectiveness and success of ecological replacement rely in part on the ability of translocatees to adapt, survive and potentially reproduce in a novel environment. We discuss the welfare aspects of translocating captive-reared non-native tortoises, Aldabrachelys gigantea and Astrochelys radiata, to two offshore Mauritian islands, and the costs and success of the projects to date.

Methodology/Principal Findings: Because tortoises are long-lived, late-maturing reptiles, we assessed the progress of the translocation by monitoring the survival, health, growth, and breeding by the founders. Between 2000 and 2011, a total of 26 A. gigantea were introduced to Ile aux Aigrettes, and in 2007 twelve sexually immature A. gigantea and twelve male A. radiata were introduced to Round Island, Mauritius. Annual mortality rates were low, with most animals either maintaining or gaining weight. A minimum of 529 hatchlings were produced on Ile aux Aigrettes in 11 years; there was no potential for breeding on Round Island. Project costs were low. We attribute the success of these introductions to the tortoises' generalist diet, habitat requirements, and innate behaviour.

Conclusions/Significance: Feasibility analyses for ecological replacement and assisted colonisation projects should consider the candidate species' welfare during translocation and in its recipient environment. Our study provides a useful model for how this should be done. In addition to serving as ecological replacements for extinct Mauritian tortoises, we found that releasing small numbers of captive-reared A. gigantea and A. radiata is cost-effective and successful in the short term. The ability to release small numbers of animals is a particularly important attribute for ecological replacement projects since it reduces the potential risk and controversy associated with introducing non-native species.

Original languageEnglish
Article number39395
Number of pages10
JournalPLoS ONE
Volume7
Issue number6
DOIs
Publication statusPublished - 19 Jun 2012

Keywords

  • PLEISTOCENE PARK
  • ASSISTED COLONIZATION
  • ALDABRA-ATOLL
  • CONSERVATION TOOL
  • NATURAL REGULATION
  • WILDING NORTH-AMERICA
  • GIANT TORTOISES
  • GOPHER TORTOISES
  • REINTRODUCTION PROGRAMS
  • GEOCHELONE-RADIATA

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