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Saved from extinction? Establishment and dispersal of Mercury Islands tusked weta, Motuweta isolata, following translocation onto mammal-free islands

Abstract

The Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), survived only on 13 ha Ahu or Middle Island, a mammal-free island in the Mercury Group, New Zealand. Between 2000 and 2009, 567 individuals were translocated in nine releases to six nearby islands from which mammals had been removed. These translocations occurred to reduce the chance of accidental extinction of the Middle Island population of only a few hundred adults and to contribute to the restoration of the other islands. All translocated insects originated from the captive-bred progeny of one male and two females collected from Middle Island between 1998 and 2001. Their establishment on Double and Red Mercury Islands, after their releases in 2000 and 2001 respectively, was confirmed by searching plots, and by using footprint tracking tunnels on Red Mercury Island between 2008 and 2012. Tracking tunnels provided better data and proved more cost effective than searching plots for detecting large tusked weta. Tracking tunnels demonstrated that the population on Red Mercury expanded outwards from the release sites by 50–100 m each year between 2009 and 2012. These weta are now estimated to be present over more than half the Island. Tusked weta have also survived on Stanley, Korapuki and Ohinau Islands after releases in 2007, but they remain within 100 m of the release sites. No confirmed progeny of the weta released on Cuvier Island in 2008 and 2011 were detected. No tusked weta were detected on Middle Island using tracking tunnels on eight occasions between 2009 and 2012, suggesting this species is likely to be locally extinct. Despite possible failure on one island, these translocations have resulted in a significant conservation success outcome.

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References

  • Butler D, Merton D (1992) The black robin: saving the world’s most endangered bird. Oxford University Press, Auckland

    Google Scholar 

  • Chappell R (2008) Final report: operational plan for eradication of ship rats (Rattus rattus), kiore (Rattus exulans), house mouse (Mus musculus) and rabbit (Oryctolagus cuniculus cuniculus) from Ohinau and Motutapere Islands. Department of Conservation, Hamilton

    Google Scholar 

  • ESRI—Environmental Systems Resource Institute (2011) ArcGIS Desktop: Release 10. ESRI, Redlands, California, USA

  • Gibb JG (1986) A New Zealand Holocene eustatic sea level curve and its application to vertical tectonic movements. In: Reilly WI, Hartford BE (eds) Recent crustal movements of the Pacific region. Royal Society of New Zealand Bulletin No. 24, Royal Society of New Zealand, Wellington

  • Gibbs GW (1990) Report on a visit to Middle Island, Mercury Group, to survey ‘tusked’ wetas, October 1989. Department of Conservation, Wellington

    Google Scholar 

  • Green CJ (2005) Using artificial refuges to translocate and establish Auckland tree weta Hemideina thoracica on Korapuki Island, New Zealand. Conserv Evid 2:94–95

    Google Scholar 

  • Hitchmough RA (2002) New Zealand threat classification system lists 2002. Threatened species occasional publication No 23. Department of Conservation, Wellington

    Google Scholar 

  • Hitchmough RA, Bull L, Cromarty P (2007) New Zealand threat classification system lists 2005. Department of Conservation, Wellington

    Google Scholar 

  • Hochkirch A, Witzenberger KA, Teerjling A, Niemeyer F (2007) Translocation of an endangered insect species, the field cricket (Gryllus campestris Linnaeus, 1758) in northern Germany. Biodivers Conserv 16:3597–3607

    Article  Google Scholar 

  • McIntyre M (2001) The ecology of some large weta species in New Zealand. In: Field LH (ed) The biology of weta, king crickets and their allies. CABI publishing, Wallingford

    Google Scholar 

  • Meads M (1994) Unpublished letter to Rob McColl 26/11/94, file No. INS-006. Department of Conservation, Wellington

  • Moeed A, Meads MJ (1987) Invertebrate survey of offshore island in relation to potential food sources for the little spotted kiwi, Apteryx oweni (Aves: Apterygidae). N Z Entomol 10:50–64

    Article  Google Scholar 

  • Molloy J, Davis A (1992) Setting priorities for the conservation of New Zealand’s threatened plants and animals. Department of Conservation, Wellington

    Google Scholar 

  • Molloy J, Davis A, Tisdall C (1994) Setting priorities for the conservation of New Zealand’s threatened plants and animals, 2nd edn. Department of Conservation, Wellington

    Google Scholar 

  • New TR (2012) Insect conservation: past, present and prospects. Springer, London

    Book  Google Scholar 

  • Oates MR, Warren MS (1990) A review of butterfly introductions in Britain and Ireland. Report for the Joint Committee for the conservation of British insects founded by the World Wide Fund for Nature

  • Schultz CB, Russell C, Wynn L (2008) Restoration, reintroduction and captive propagation for at-risk butterflies: a review of British and American conservation efforts. Isr J Ecol Evol 54:41–61

    Article  Google Scholar 

  • Stringer IAN, Chappell R (2008) Possible rescue from extinction: transfer of a rare new Zealand tusked weta to islands in the Mercury Group. J Insect Conserv 12:177–188

    Article  Google Scholar 

  • Stringer IAN, Mack H, Grant EA, Winks CJ (2006) Growth and development of captive reared Mercury island tusked weta, Motuweta isolata Johns (Orthoptera: Anostostomatidae). N Z Entomol 29:5–19

    Article  Google Scholar 

  • Thompson P (1992) Proposal to transfer MITW to captivity. Unpublished report, file No. INS-006. Department of Conservation, Wellington

  • Towns DR, Atkinson IAE (2004) Restoration plan for Korapuki Island (Mercury Islands), New Zealand 2004–2014. Department of Conservation, Wellington

    Google Scholar 

  • Towns DR, Broome KG (2003) From small Maria to massive Campbell: forty years of rat eradications from New Zealand islands. N Z J Zool 30:377–398

    Article  Google Scholar 

  • Towns DR, Atkinson IAE, Daugherty CH (1990) Ecological restoration of New Zealand Islands: introduction. In :Towns DR, Daugherty CH, Atkinson IAE (eds) Ecological restoration of New Zealand islands. Conservation Sciences Publication 2. Department of Conservation, Wellington

  • Veitch CR, Bell BD (1990) Eradication of introduced animals from the islands of New Zealand. In: Towns DR, Daugherty CH, Atkinson IAE (eds) Ecological restoration of New Zealand islands. Conservation Sciences Publication 2. Department of Conservation, Wellington

  • Watts CH, Thornburrow D, Green C, Agnew W (2008) A novel method for detecting a threatened New Zealand giant weta (Orthoptera: Anostostomatidae) using tracking tunnels. N Z J Ecol 32:65–71

    Google Scholar 

  • Watts C, Stringer I, Thornburrow D, MacKenzie D (2011a) Are footprint tracking tunnels suitable for monitoring giant weta (Orthoptera: Anostostomatidae)? Abundance, distribution and movement in relation to tracking rates. J Insect Conserv 15:433–443

    Article  Google Scholar 

  • Watts CH, Armstrong DP, Innes J, Thornburrow D (2011b) Dramatic increases in weta (Orthoptera) following mammal eradication on Maungatautari—evidence from pitfalls and tracking tunnels. N Z J Ecol 35:261–272

    Google Scholar 

  • Winks C, Ramsay G (1998) Captive rearing of the Middle island tusked weta. Research Contract Report LC9899/10. Department of Conservation, Wellington

  • Winks CJ, Fowler SV, Ramsay GW (2002) Captive-rearing of the Middle Island tusked weta. Science for conservation 197. Department of Conservation, Wellington

  • WRAPS (2007) Aerial Photography—WRAPS 2007—GIS Layer. Terralink International Limited and Waikato Regional Aerial Photography Syndicate

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Acknowledgments

This research was supported by Core funding for Crown Research Institutes from the Ministry of Business, Innovation and Employment’s Science and Innovation Group under CO9X0503 and DOC investigation No. 3124. Thank you to Lesley McKay, David Ruscoe, Esta Chappell, and Craig Briggs who assisted with fieldwork. Sincere thanks to Chris Winks for footprinting and measuring the feet of captive tusked weta. John Innes, Bill Lee, Don Newman, and Anne Austin provided useful comments on manuscript.

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Correspondence to Corinne Watts.

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Stringer, I., Watts, C., Thornburrow, D. et al. Saved from extinction? Establishment and dispersal of Mercury Islands tusked weta, Motuweta isolata, following translocation onto mammal-free islands. J Insect Conserv 18, 203–214 (2014). https://doi.org/10.1007/s10841-014-9631-y

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  • DOI: https://doi.org/10.1007/s10841-014-9631-y

Keywords

  • Island conservation
  • Monitoring
  • Tracking tunnels
  • Threatened taxa