Biological invasions are among the main drivers of biodiversity losses. As threats from biological invasions increase, one of the most urgent tasks is to identify areas of high vulnerability. However, the lack of comprehensive information on the impacts of invasive alien species (IAS) is a problem especially on islands, where most of the recorded extinctions associated with IAS have occurred. Here we provide a global, network-oriented analysis of IAS on islands. Using network analysis, we structured 27,081 islands and 437 threatened vertebrates into 21 clusters, based on their profiles in term of invasiveness and shared vulnerabilities. These islands are mainly located in the Southern Hemisphere and many are in biodiversity hotspots. Some of the islands share similar characteristics regarding their connectivity that could be useful for understanding their response to invasive species. The major invaders found in these clusters of islands are feral cats, feral dogs, pigs and rats. Our analyses reveal those IAS that systematically act alone or in combination, and the pattern of shared IAS among threatened species, providing new information to implement effective eradication strategies. Combined with further local, contextual information this can contribute to global strategies to deal with IAS.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Kier, G. et al. Global patterns of plant diversity and floristic knowledge. J. Biogeogr. 32, 1107–1116 (2005).

  2. 2.

    Bellard, C., Cassey, P. & Blackburn, T. M. Alien species as a driver of recent extinctions. Biol. Lett. 12, 20150623 (2016).

  3. 3.

    Bellard, C., Genovesi, P. & Jeschke, J. M. Global patterns in threats to vertebrates by biological invasions. Proc. R. Soc. B 283, 20152454 (2016).

  4. 4.

    Jones, H. P. et al. Invasive mammal eradication on islands results in substantial conservation gains. Proc. Natl Acad. Sci. USA 113, 4033–4038 (2016).

  5. 5.

    Nogales, M. et al. Feral cats and biodiversity conservation: the urgent prioritization of island management. Bioscience 63, 804–810 (2013).

  6. 6.

    Helmstedt, K. J. et al. Prioritizing eradication actions on islands: it’s not all or nothing. J. Appl. Ecol. 53, 733–741 (2016).

  7. 7.

    Dawson, J. et al. Prioritizing islands for the eradication of invasive vertebrates in the United Kingdom overseas territories. Conserv. Biol. 29, 143–153 (2015).

  8. 8.

    Early, R. et al. Global threats from invasive alien species in the twenty-first century and national response capacities. Nat. Commun. 7, 12485 (2016).

  9. 9.

    McCreless, E. E. et al. Past and estimated future impact of invasive alien mammals on insular threatened vertebrate populations. Nat. Commun. 7, 12488 (2016).

  10. 10.

    Gallardo, B., Clavero, M., Sánchez, M. I. & Vilà, M. Global ecological impacts of invasive species in aquatic ecosystems. Glob. Change Biol. 22, 151–163 (2016).

  11. 11.

    Kumschick, S. et al. Ecological impacts of alien species: quantification, scope, caveats, and recommendations. Bioscience 65, 55–63 (2015).

  12. 12.

    Carrion, V., Donlan, C. J., Campbell, K. J., Lavoie, C. & Cruz, F. Archipelago-wide island restoration in the Galápagos Islands: reducing costs of invasive mammal eradication programs and reinvasion risk. PLoS ONE 6, e18835 (2011).

  13. 13.

    Courchamp, F., Chapuis, J.-L. & Pascal, M. Mammal invaders on islands: impact, control and control impact. Biol. Rev. Camb. Philos. Soc. 78, 347–383 (2003).

  14. 14.

    Berman, M. et al. Overview of the distribution, habitat association and impact of exotic ants on native ant communities in New Caledonia. PLoS ONE 8, e67245 (2013).

  15. 15.

    Myers, N., Mittermeier, R. A., Mittermeier, C. G., Da Fonseca, G. A. & Kent, J. Biodiversity hotspots for conservation priorities. Nature 403, 853–858 (2000).

  16. 16.

    Sloan, S., Jenkins, C. N., Joppa, L. N., Gaveau, D. L. A. & Laurance, W. F. Remaining natural vegetation in the global biodiversity hotspots. Biol. Conserv. 177, 12–24 (2014).

  17. 17.

    Bonnaud, E. et al. The diet of feral cats on islands: a review and a call for more studies. Biol. Invasions 13, 581–603 (2011).

  18. 18.

    Medina, L. I. X. M., Bonnaud, E., Vidal, E. & Tershy, B. R. A global review of the impacts of invasive cats on island endangered vertebrates. Glob. Change Biol. 17, 3503–3510 (2011).

  19. 19.

    Jones, H. P. et al. Severity of the effects of invasive rats on seabirds: a global review. Conserv. Biol. 22, 16–26 (2008).

  20. 20.

    Glen, A. S. et al. Eradicating multiple invasive species on inhabited islands: the next big step in island restoration? Biol. Invasions 15, 2589–2603 (2013).

  21. 21.

    Keitt, B. et al. Best practice guidelines for rat eradication on tropical islands. Biol. Conserv. 185, 17–26 (2015).

  22. 22.

    Bergstrom, D. M. et al. Indirect effects of invasive species removal devastate World Heritage Island. J. Appl. Ecol. 46, 73–81 (2009).

  23. 23.

    Rayner, M. J., Hauber, M. E., Imber, M. J., Stamp, R. K. & Clout, M. N. Spatial heterogeneity of mesopredator release within an oceanic island system. Proc. Natl Acad. Sci. USA 104, 20862–20865 (2007).

  24. 24.

    Lips, K. R. Overview of chytrid emergence and impacts on amphibians. Phil. Trans. R. Soc. Lond. B 371, 20150465 (2016).

  25. 25.

    B. Keitt et al. in Island Invasives: Eradication and Management (eds Veitch, C. R., Clout, M. N. & Towns, D. R.) 74–77 (IUCN, Gland, 2011).

  26. 26.

    Hoffmann, B. D., Luque, G. M., Bellard, C., Holmes, N. D. & Donlan, J. Improving invasive ant eradication as a conservation tool: a review. Biol. Conserv. 198, 37–49 (2016).

  27. 27.

    Spatz, D. R. et al. The biogeography of globally threatened seabirds and island conservation opportunities. Conserv. Biol. 28, 1282–1290 (2014).

  28. 28.

    Doherty, T. S., Dickman, C. R., Nimmo, D. G. & Ritchie, E. G. Multiple threats, or multiplying the threats? Interactions between invasive predators and other ecological disturbances. Biol. Conserv. 190, 60–68 (2015).

  29. 29.

    The IUCN Red List of Threatened Species. (IUCN, Gland, 2015); http://www.iucnredlist.org/

  30. 30.

    Bird Species Distribution Maps of the World. Version 4.0. (BirdLife International, Cambridge and NatureServe, Arlington, 2014); http://www.birdlife.org/datazone/info/spcdownload

  31. 31.

    Global Invasive Species Database (IUCN/SSC Invasive Species Specialist Group, 2016); http://www.issg.org/database

  32. 32.

    Mace, G. M. et al. Quantification of extinction risk: IUCN’s system for classifying threatened species. Conserv. Biol. 22, 1424–1442 (2008).

  33. 33.

    Salafsky, N. et al. A standard lexicon for biodiversity conservation: unified classifications of threats and actions. Conserv. Biol. 22, 897–911 (2008).

  34. 34.

    Vilhena, D. & Antonelli, A. A network approach for identifying and delimiting biomes. Nat. Commun. 6, 6848 (2014).

  35. 35.

    Rosvall, M. & Bergstrom, C. T. Multilevel compression of random walks on networks reveals hierarchical organization in large integrated systems. PLoS ONE 6, e18209 (2011).

  36. 36.

    Graham, J. I. M. et al. Vision of a cyberinfrastructure for nonnative, invasive species management. Bioscience 58, 263–268 (2008).

  37. 37.

    Lancichinetti, A. & Fortunato, S. Community detection algorithms: a comparative analysis. Phys. Rev. E 80, 056117 (2009).

  38. 38.

    Aldecoa, R. et al. Exploring the limits of community detection strategies in complex networks. Sci. Rep. 3, 2216 (2013).

  39. 39.

    Rosvall, M., Axelsson, D. & Bergstrom, C. T. The map equation. Eur. Phys. J. Spec. Top. 178, 13–23 (2009).

  40. 40.

    Rosvall, M. & Bergstrom, C. T. Maps of random walks on complex networks reveal community structure. Proc. Natl Acad. Sci. USA 105, 1118–1123 (2008).

  41. 41.

    Tylianakis, J. M., Laliberte, E., Nielsen, A. & Bascompte, J. Conservation of species interaction networks. Biol. Conserv. 143, 2270–2279 (2010).

  42. 42.

    Pluess, T. et al. When are eradication campaigns successful? A test of common assumptions. Biol. Invasions 14, 1365–1378 (2012).

  43. 43.

    Wickham, H. ggplot2: Elegant Graphics for Data Analysis (Springer, New York, 2009); http://ggplot2.org.

  44. 44.

    Bivand, R. & Lewin-Koh, N. maptools: Tools for Reading and Handling Spatial Objects. R package version 0.9-2 (2016); https://cran.r-project.org/package=maptools

  45. 45.

    Csárdi, G. & Nepusz, T. The igraph Software Package for Complex Network Research (InterJournal, 2006); http://igraph.org/

  46. 46.

    Wickham, H. & Francois, R., Henry, L. & Müller, K. dplyr: A Grammar of Data Manipulation. R package version 0.5.0 (2015); https://cran.r-project.org/package=dplyr

  47. 47.

    Bastian, M. & Heymann, S. gephi: an open source software for exploring and manipulating networks (2009); http://www.aaai.org/ocs/index.php/ICWSM/09/paper/view/154

  48. 48.

    Mittermeier, R. A. A. et al. Hotspots Revisited: Earth’s Biologically Richest and Most Endangered Ecoregions (CEMEX, Mexico City, 2004).

Download references


C.B. was supported by an Axa Fellowship. We thank S. Pagad; C. Leclerc and J. Jeschke for their comments on an earlier version of the manuscript; F. Courchamp for fruitful discussions.

Author information

Author notes

    • Jean-François Rysman

    Present address: LMD/IPSL, CNRS UMR 8539, École Polytechnique, Université Paris Saclay, ENS, PSL Research University, Sorbonne Universités, UPMC Univ Paris 06, Palaiseau, France

  1. Céline Bellard and Jean-François Rysman contributed equally to this work.


  1. Department of Genetics, Evolution and Environment, Center for Biodiversity and Environment Research, University College London, London, UK

    • Céline Bellard
    •  & Georgina M. Mace
  2. Institute of Zoology, Zoological Society of London, London, UK

    • Jean-François Rysman
  3. Biologie des Organismes et Ecosystèmes Aquatiques (BOREA, UMR 7208), Muséum National d’Histoire Naturelle, Université Pierre et Marie Curie, Université de Caen Basse-Normandie, Université des Antilles, CNRS, IRD, Sorbonne Universités, Paris, France

    • Boris Leroy


  1. Search for Céline Bellard in:

  2. Search for Jean-François Rysman in:

  3. Search for Boris Leroy in:

  4. Search for Chantal Claud in:

  5. Search for Georgina M. Mace in:


C.B. and J.-F.R. conceived and designed the study with contributions by G.M.M. J.-F.R. and C.B. carried out the analyses, B.L. provided the initial version of the computing code. C.B. and J.-F.R. wrote the first draft of the manuscript and all authors substantially contributed to interpreting and writing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Céline Bellard.

Electronic supplementary material

About this article

Publication history






Further reading