9 Facts Everybody Ought to Know About Invasive Species

What are invasive species and how do they impact island wildlife and ecosystems?

Test your knowledge. How many invasive species facts do you already know? 

  1. According to the National Invasive Species Information Center, an invasive species is:
    1. Non-native (or alien) to the ecosystem under consideration, and
    2. Whose introduction causes (or is likely to cause) harm to human health, the economy, or the environment.
  1. The majority of all recorded extinctions have occurred on islands with invasive species as the primary causes[1].
  1. Invasive mammals represent a key threat to island biodiversity[2], directly impacting native animals via predation, competition for resources, and destruction of sensitive habitat.
  1. Rodents are some of the most prolific invasive species and are considered among the world’s 100 worst and are estimated to occur on 80% of the world’s archipelagos[3].
  1. Invasive rodents pose health risks vectors of diseases such as leptospirosis[4].
  1. Invasive species are introduced outside their native range often with human aid. Rats may accidentally be introduced as stowaways on ships, and historically, species such as goats were often deliberately introduced as a food source[5].
  1. Invasive species such as rodents can reproduce rapidly. Once introduced, they can swiftly take over the native habitats they invade[6].
  1. Invasive species eradications have become a powerful tool to prevent extinctions and restore ecosystems[7].
  1. Invasive rodents have been successfully eradicated from more than 600 islands[8] as a response to their threat to island biodiversity values. Once rodents are removed, the recovery of native species plants and animals on islands can be spectacular[9].

Many seabirds lay their eggs in the open, such as this Laysan Albatross, leaving them extremely vulnerable to the impacts of invasive species.
Photography: Olivier Langrand / Island Conservation


[1] Bernie R. Tershy, Kuo-Wei Shen, Kelly M. Newton, Nick D. Holmes, and Donald A. Croll (2015) The Importance of Islands for the Protection of Biological and Linguistic Diversity. BioScience Advance Access

[2] Cuthbert, R., and G. Hilton. 2004. Introduced house mice Mus musculus: a significant predator of threatened and endemic birds on Gough Island, South Atlantic Ocean? Biological Conservation 117:483– 489.

Towns, D. R., I. A. E. Atkinson, and C. H. Daugherty. 2006. Have the harmful effects of introduced rats on islands been exaggerated? Biological Invasions 8:863–891.

[3] Atkinson, I. A. E. 1985. The spread of commensal species of Rattus to oceanic islands and their effects on island avifaunas. Pages 35–81 in P. J. Moors, editor. Conservation of island birds: case studies for the management of threatened island species. International Council for Bird Preservation, Cambridge, United Kingdom

[4] Meerburg, B.G., Singleton, G.R., Kijlstra, A., 2009. Rodent-borne diseases and their risks for public health. Crit. Rev. Microbiol. 35, 221–270.

[5] Bellingham PJ, Towns DR, Cameron EK, et al. (2010) New Zealand island restoration: seabirds, predators, and the importance of history. New Zealand Journal of Ecology 34:115-136

[6] Russell JC, Towns DR, Clout MN (2008) Review of rat invasion biology: Implications for island biosecurity.  Science for Conservation 286, Department of Conservation, Wellington

[7] Donlan, C. J., B. R. Tershy, K. Campbell, and F. Cruz. 2003b. Research for requiems: the need for more collaborative action in invasive species management and conservation. Conservation Biology 17:1850–1851.

Towns, D. R., and K. G. Broome. 2003. From small Maria to massive Campbell: forty years of rat eradications from New Zealand islands. New Zealand Journal of Zoology 30:377–398

[8] DIISE, 2014. The Database of Island Invasive Species Eradications, developed by IC, Coastal Conservation Action

Laboratory UCSC, IUCN SSC Invasive Species Specialist Group, University of Auckland and Landcare Research New Zealand. http://diise.islandconservation.org.

[9] Bellingham PJ, Towns DR, Cameron EK, et al. (2010) New Zealand island restoration: seabirds, predators, and the importance of history. New Zealand Journal of Ecology 34:115-136

About Sally Esposito

Sally received her BA in Journalism with a minor in Environmental Business Economics from the School of Environmental and Biological Sciences at Rutgers University.

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