Biological Invasions

, Volume 11, Issue 7, pp 1719–1733 | Cite as

Eradications as reverse invasions: lessons from Pacific rat (Rattus exulans) removals on New Zealand islands

  • David R. Towns
Invasive Rodents on Islands


Eradications of kiore or Pacific rats (Rattus exulans) from islands around New Zealand have been followed by responses from resident species of coastal plants, invertebrates, reptiles and seabirds. These responses are compared with an invasion by ship rats (Rattus rattus), which devastated populations of invertebrates, birds and bats. Post-eradication responses only approximate the effects of invasions because recovery is limited to the residual pool of native species. Greater effects of kiore are indicated by adding incompatible species confined to rat-free locations. The extended list includes at least 15 species of invertebrates, two species of frogs, tuatara (Sphenodon punctatus), 11 species of lizards and 9 species of seabirds. The analyses indicate direct and indirect effects of kiore similar to those reported after ship rat invasions. This is despite indications from the literature that kiore are the least damaging of the three commensal rat species.


Invasion Ship rats (Rattus rattusDirect and indirect effects Fruit and seed predation Honey dew scale Tuatara (Sphenodon punctatusBurrowing seabirds 



I thank Ian Atkinson, Grant Harper and James Russell for their useful comments on the manuscript, the organisers of the conference on Rats, Humans and their Impacts on Islands for their invitation to present this paper and two anonymous reviewers for their thoughtful comments.


  1. Alton H (2000) Nature’s sovereignty rules Northwestern Hawaiian isles. Honolulu Star Bulletin, 14 October 2000Google Scholar
  2. Athen JS, Tuggle HD, Ward JV, Welch DJ (2002) Avifaunal extinctions, vegetation change, and Polynesian impacts in prehistoric Hawai’i. Archaeol Ocean 37:57–78Google Scholar
  3. Atkinson IAE (1985) The spread of commensal species of Rattus to oceanic islands and their effects on island avifaunas. In: Moors PJ (ed) Conservation of island birds. ICBP Technical Publication No. 3, pp. 35–81Google Scholar
  4. Atkinson IAE (1986) Rodents on New Zealand’s northern offshore islands: distribution, effects and precautions against further spread. In: Wright AE, Beever RE (eds) The offshore islands of northern New Zealand. New Zealand Department of Lands and Survey Information Series 16, Wellington, pp 13–40Google Scholar
  5. Atkinson IAE (1989) Introduced animals and extinctions. In: Western DC, Pearl MC (eds) Conservation for the twenty-first century. Oxford University Press, New York, pp 54–75Google Scholar
  6. Atkinson IAE, Bell BD (1973) Offshore and outlying islands. In: Williams GR (ed) The natural history of New Zealand. A.H. and A.W. Reed, Wellington, pp 372–392Google Scholar
  7. Atkinson IAE, Towns DR (2005) Kiore. In: King CM (ed) The handbook of New Zealand mammals, 2nd edn. Oxford University Press, Melbourne, pp 159–174Google Scholar
  8. Ballance A (2007) Don Merton the man who saved the black robin. Reed, AucklandGoogle Scholar
  9. Beaglehole JC (ed) (1961) The journals of Captain James Cook on his voyages of discovery. The voyage of resolution and adventure, vol 2. Cambridge University Press for the Hakluyt Society, Cambridge, pp 1772–1775Google Scholar
  10. Beauchamp AJ, Butler DJ, King D (1999) Weka (Gallirallus australis) recovery plan. Department of Conservation, Wellington 90Google Scholar
  11. Begg AC, Begg NC (1969) James Cook and New Zealand. Government Printer, WellingtonGoogle Scholar
  12. Beggs J (2001) The ecological consequences of social wasps (Vespula sp.) invading an ecosystem that has an abundant carbohydrate resource. Biol Conserv 99:17–28CrossRefGoogle Scholar
  13. Bell BD (1978) The Big South Cape islands rat irruption. In: Dingwall PR, Atkinson IAE, Hay C (eds) The ecology and control of rodents in New Zealand nature reserves. Department of Lands and Survey Information Series 4, Wellington, pp 33–40Google Scholar
  14. Blackburn A (1965) Muttonbird islands diary. Notornis 12:191–207Google Scholar
  15. Brook FJ (1999) Changes in the landsnail fauna of Lady Alice Island, northeastern New Zealand. J R Soc N Z 29:135–157Google Scholar
  16. Brown KP (1997) Predation at nests of two New Zealand endemic passerines; implications for bird community restoration. Pac Conserv Biol 3:91–98Google Scholar
  17. Campbell JD, Atkinson IAE (1999) Effects of kiore (Rattus exulans) on recruitment of indigenous coastal trees on northern offshore islands of New Zealand. J R Soc N Z 29:265–290Google Scholar
  18. Campbell JD, Atkinson IAE (2002) Depression of tree recruitment by the Pacific rat (Rattus exulans Peale) on New Zealand’s northern offshore islands. Biol Conserv 107:19–35CrossRefGoogle Scholar
  19. Campbell JD, Moller H, Ramsay GW, Watt JC (1984) Observations on foods of kiore (Rattus exulans) found in husking stations on northern offshore islands of New Zealand. N Z J Ecol 7:131–138Google Scholar
  20. Clout MN, Russell JC (2006) The eradication of introduced mammals from New Zealand islands. In: Koike F, Clout MN, Kawamichi M, de Poorter M, Iwatsuki K (eds) Assessment and control of biological invasion risks. Shoukadoh Book Sellers, Kyoto and IUCN, Gland, pp 127–141Google Scholar
  21. Cole NC, Jones CG, Harris S (2005) The need for enemy-free space: the impacts of an invasive gecko on island endemics. Biol Conserv 125:467–474CrossRefGoogle Scholar
  22. Courchamp F, Caut S (2005) Use of biological invasions and their control to study the dynamics of interacting populations. In: Cadotte MW, McMahon SM, Fukami T (eds) Conceptual ecology and invasions biology. Springer, New York, pp 253–279Google Scholar
  23. Cree A, Daugherty CH, Hay JM (1995) Reproduction of a rare reptile, the tuatara Sphenodon punctatus, on rat-free and rat-inhabited islands in New Zealand. Conserv Biol 9:373–383CrossRefGoogle Scholar
  24. Cromarty PL, Broome KG, Cox A, Empson RA, Hutchinson WM, McFadden I (2002) Eradication planning for invasive alien animal species on islands—the approach developed by the New Zealand Department of Conservation. In: Veitch CR, Clout MN (eds) Turing the tide; the eradication of invasive species. IUCN SSC Invasive Species Specialist Group, IUCN Gland and Cambridge, pp 85–91Google Scholar
  25. Crook IG (1973) The tuatara, Sphenodon punctatus Gray, on islands with and without populations of the Polynesian rat, Rattus exulans (Peale). Proc N Z Ecol Soc 20:115–120Google Scholar
  26. Crowe A (2002) Which New Zealand insect?. Penguin Books, AucklandGoogle Scholar
  27. Department of Conservation (2002) The penguin guide to New Zealand wildlife. Penguin Books, AucklandGoogle Scholar
  28. Elliot GP, Merton DV, Jansen PW (2001) Intensive management of a critically endangered species: the kakapo. Biol Conserv 99:121–133CrossRefGoogle Scholar
  29. Fukami T, Wardle DA, Bellingham PJ, Mulder CPH, Towns DR, Yeates GW, Bonner KI, Durrett MS, Grant-Hoffman MN, Williamson WM (2006) Above- and below-ground impacts of introduced predators in seabird-dominated island ecosystems. Ecol Lett 9:1299–1307PubMedCrossRefGoogle Scholar
  30. Gaskin CP, Baird KA (2005) Observations of black and white storm petrels in the Hauraki Gulf, November 2003 to June 2005; were they New Zealand storm petrels? Notornis 52:181–194Google Scholar
  31. Gaze P (2001) Tuatara recovery plan 2001–2011. Threatened species recovery plan 47. Department of Conservation, WellingtonGoogle Scholar
  32. Gibbs GW (2008) The end of an 80-million year experiment: a review of evidence describing the impact of introduced rodents on New Zealand’s ‘mammal-free’ invertebrate fauna. Biol Invas. doi: 10.1007/s10530-008-9408-x Google Scholar
  33. Gill BJ, Whitaker AH (1996) New Zealand frogs and reptiles. David Bateman, AucklandGoogle Scholar
  34. Green CJ (2002) Recovery of invertebrate populations on Tiritiri Matangi Island, New Zealand following eradication of Pacific rats (Rattus exulans). In: Veitch CR, Clout MN (eds) Turing the tide; the eradication of invasive species. IUCN SSC Invasive Species Specialist Group, IUCN Gland and Cambridge, p 407Google Scholar
  35. Guthrie-Smith H (1925) Bird life on island and shore. William Blackwood and Sons, Edinburgh and LondonGoogle Scholar
  36. Harper GA (2007) Detecting predation of a burrow-nesting seabird by two introduced predators, using stable isotopes, diet analysis, and experimental removals. Wildl Res 34:443–453CrossRefGoogle Scholar
  37. Heather BD, Robertson HA (2000) The field guide to the birds of New Zealand. Penguin, AucklandGoogle Scholar
  38. Hoare JM, Pledger S, Nelson NJ, Daugherty CH (2007) Avoiding aliens: behavioural plasticity in habitat use enables large, nocturnal geckos to survive Pacific rat invasions. Biol Conserv 136:510–519CrossRefGoogle Scholar
  39. Holdaway RN (1999) Introduced predators and avifaunal extinctions in New Zealand. In: MacPhee RDE (ed) Extinctions in near time. Kluwer Academic/Plenum Publishers, New York, pp 189–238Google Scholar
  40. Hunt TL (2007) Rethinking Easter Island’s ecological catastrophe. J Archaeol Sci 34:485–502CrossRefGoogle Scholar
  41. Imber MJ, West JA, Cooper WJ (2003) Breeding biology of Cook’s petrel (Pterodroma cookii) on Hauturu (Little Barrier Island) and Whenua Hou (Codfish Island). Notornis 50:221–230Google Scholar
  42. Innes J (2005) Ship rat. In: King CM (ed) The handbook of New Zealand mammals, 2nd edn. Melbourne, Oxford University Press, pp 187–203Google Scholar
  43. Kuschel G, Worthy TH (1996) Past distribution of large weevils (Coleoptera:Curculionidae) in the South Island, New Zealand, based on Holocene fossil remains. N Z Entomol 19:15–22Google Scholar
  44. Lloyd B (2005a) Lesser short-tailed bat. In: King CM (ed) The handbook of New Zealand mammals, 2nd edn. Melbourne, Oxford University Press, pp 110–126Google Scholar
  45. Lloyd B (2005b) Greater short-tailed bat. In: King CM (ed) The handbook of New Zealand mammals, 2nd edn. Melbourne, Oxford University Press, pp 127–129Google Scholar
  46. Markwell T, Daugherty CH (2002) Invertebrate and lizard abundance is greater of seabird-inhabited islands than on seabird-free islands in the Marlborough Sounds, New Zealand. Ecoscience 9:293–299Google Scholar
  47. McCallum J (1986) Evidence of predation by kiore upon lizards from the Mokohinau Islands. N Z J Ecol 9:83–87Google Scholar
  48. McCallum J, Bellingham PJ, Hay JR, Hitchmough RA (1984) The birds of the Chickens Islands, northern New Zealand. Tane 30:105–124Google Scholar
  49. McGuinness CA (2001) The conservation requirements of New Zealand’s nationally threatened invertebrates. Threatened Species Occasional Publication 20. Department of Conservation, WellingtonGoogle Scholar
  50. McIntyre M (2001) The ecology of some large weta species in New Zealand. In: Field LH (ed) The biology of wetas, king crickets and their allies. Wallingford, CAB International, pp 225–242Google Scholar
  51. Meads M (1990) Forgotten fauna. DSIR Publishing, WellingtonGoogle Scholar
  52. Mulder CPH, Keall SN (2001) Burrowing seabirds and reptiles: impacts on seeds, seedlings and soils in an island forest in New Zealand. Oecologia 127:350–360CrossRefGoogle Scholar
  53. Mulder CPH, Grant-Hoffman MN, Towns DR, Bellingham PJ, Wardle DA, Durrett MS, Fukami T, Bonner KI (2008) Direct and indirect effects of rats: does rat eradication restore ecosystem functioning of New Zealand seabird islands? Biol Invas. doi: 10.1007/s10530-008-9396-x Google Scholar
  54. Myers JH, Simberloff D, Kuris AM, Carey JR (2000) Eradication revisited: dealing with exotic species. Trends Ecol Evol 15:316–320PubMedCrossRefGoogle Scholar
  55. Newman DG (1987) Burrow use and population densities of tuatara (Sphenodon punctatus) and how they are influenced by fairy prions (Pachyptila turtur) on Stephens Island, New Zealand. Herpetologica 43:336–344Google Scholar
  56. Parrish GR, Sherley GH (1993) Invertebrates of Moutopao Island, Northland, New Zealand. Tane 34:45–52Google Scholar
  57. Pierce RJ (2002) Kiore (Rattus exulans) impact on breeding success of Pycroft’s petrels and little shearwaters. DOC Science Internal Series 39. Department of Conservation, WellingtonGoogle Scholar
  58. Poole AL, Adams NM (1990) Trees and shrubs of New Zealand. DSIR Publishing, WellingtonGoogle Scholar
  59. Reserves Act (1977) New Zealand Government, WellingtonGoogle Scholar
  60. Rayner M, Hauber ME, Imber MJ, Stamp RK, Clout MN (2007) Spatial heterogeneity of mesopredator release within an oceanic island system. Proc Natl Acad Sci USA 104:20862–20865PubMedCrossRefGoogle Scholar
  61. Reed AH, Reed AW (1969) Captain Cook in New Zealand. Reed, WellingtonGoogle Scholar
  62. Robb J (1986) New Zealand amphibians and reptiles in colour. Collins, Auckland Revised editionGoogle Scholar
  63. Tennyson A, Martinson P (2006) Extinct birds of New Zealand. Te Papa Press, WellingtonGoogle Scholar
  64. Towns DR (1991) Response of lizard assemblages in the Mercury Islands, New Zealand, to removal of an introduced rodent: the kiore (Rattus exulans). J R Soc N Z 21:119–136Google Scholar
  65. Towns DR (1996) Changes in habitat use by lizards on a New Zealand island following removal of the introduced Pacific rat Rattus exulans. Pac Conserv Biol 2:286–292Google Scholar
  66. Towns DR (1999) Cyclodina spp. skink recovery plan. Threatened Species Recovery Plan No. 27. Department of Conservation, WellingtonGoogle Scholar
  67. Towns DR (2002a) Interactions between geckos, honeydew scale insects and host plants revealed on islands in northern New Zealand, following eradication of introduced rats and rabbits. In: Veitch CR, Clout MN (eds) Turing the tide; the eradication of invasive species. IUCN SSC Invasive Species Specialist Group, IUCN Gland and Cambridge, pp 329–335Google Scholar
  68. Towns DR (2002b) Korapuki Island as a case study for restoration of insular ecosystems in New Zealand. J Biogeogr 29:593–607CrossRefGoogle Scholar
  69. Towns DR, Atkinson IAE (2004) Restoration plan for Korapuki Island (Mercury Islands) 2004–2024. Department of Conservation, WellingtonGoogle Scholar
  70. Towns DR, Broome KG (2003) From small Maria to massive Campbell: 40 years of rat eradications from New Zealand islands. N Z J of Zool 30:377–398Google Scholar
  71. Towns DR, Daugherty CH (1994) Patterns of range contractions and extinctions in the New Zealand herpetofauna following human colonisation. N Z J of Zool 21:325–339Google Scholar
  72. Towns DR, Simberloff D, Atkinson IAE (1997) Restoration of New Zealand islands: redressing the effects of introduced species. Pac Conserv Biol 3:99–124Google Scholar
  73. Towns DR, Parrish GR, Westbrooke I (2003) Inferring vulnerability to introduced predators without experimental demonstration: case study of Suter’s skink in New Zealand. Conserv Biol 17:1361–1371CrossRefGoogle Scholar
  74. Towns DR, Atkinson IAE, Daugherty CH (2006) Have the harmful effects of introduced rats on islands been exaggerated? Biol Invasions 8:863–891CrossRefGoogle Scholar
  75. Towns DR, Parrish GR, Tyrrell CL, Ussher GT, Cree A, Newman DG, Whitaker AH, Westbrooke I (2007) Responses of tuatara (Sphenodon punctatus) to removal of Pacific rats from islands. Conserv Biol 21:1021–1031PubMedCrossRefGoogle Scholar
  76. Ussher GT (1999) Tuatara (Sphenodon punctatus) feeding ecology in the presence of kiore (Rattus exulans). N Z J of Zool 26:117–125Google Scholar
  77. Veltman C (1996) Investigating causes of population decline in New Zealand plants and animals: introduction to a symposium. New Zealand Journal of Ecology 20:1–5Google Scholar
  78. Watt JC (1986) Beetles (Coleoptera) of the offshore islands of northern New Zealand. In: Wright AE, Beever RE (eds) The offshore islands of northern New Zealand. Department of Lands and Survey Information Series 16, Wellington, pp 221–228Google Scholar
  79. Whitaker AH (1978) The effects of rodents on reptiles and amphibians. In: Dingwall PR, Atkinson IAE, Hay C (eds) The ecology and control of rodents in New Zealand nature reserves. . Department of Lands and Survey Information Series 4, Wellington, pp 75–86Google Scholar
  80. Wilmshurst JM, Anderson AJ, Higham TFG, Worthy TH (2008) Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat. Proc Natl Acad Sci USA 105:7676–7680PubMedCrossRefGoogle Scholar
  81. Worthy TH (1987) Osteology of Leiopelma (Amphibia: Leiopelmatidae) and descriptions of three new subfossil Leiopelma species. J R Soc N Z 17:201–251Google Scholar
  82. Worthy TH (1991) Fossil skink bones from Northland, New Zealand, and description of a new species of Cyclodina, Scincidae. J R Soc N Z 21:329–348Google Scholar
  83. Worthy TH, Holdaway RN (2002) The lost world of the moa. Canterbury University Press, ChristchurchGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Research & Development Group, Department of ConservationNewton, AucklandNew Zealand

Personalised recommendations