Island tameness

Island tameness is the tendency of many populations and species of animals living on isolated islands to lose their wariness of potential predators, particularly of large animals. The term is partly synonymous with ecological naïvete, which also has a wider meaning referring to the loss of defensive behaviors and adaptations needed to deal with these "new" predators. Species retain such wariness of predators that exist in their environment, for example a Hawaiian Goose retains its wariness of hawks, but lose such behaviors associated with mammals or other predators not found in their historical range.

Island tameness can be highly maladaptive in situations where humans have introduced predators, intentionally or accidentally, such as pigs, dogs, rats or cats, to islands where ecologically naïve fauna lives. It has also made many island species, such as the long-extinct Dodo or the Short-tailed Albatross, vulnerable to human hunting. In many instances the native species are unable to learn to avoid new predators, or change their behavior to minimize their risk. This tameness is eventually lost or reduced in some species but many island populations are too small or breed too slowly for the affected species to adapt quickly enough. When combined with other threats, such as habitat loss, this has led to the extinction of several species (such as the Laysan Rail and the Stephens Island Wren) and continues to threaten several others. The only conservation techniques that can help endangered species threatened by novel introduced species are creating barriers to exclude predators or eradicating those species. New Zealand has pioneered the use of offshore islands free of introduced species to serve as wildlife refuges for ecologically naïve species.

References

* Quammen, D., 1996. "The Song of the Dodo". New York: Touchstone
* Blazquez M. C., Rodriguez-Estrella R., Delibes M (1997) "Escape behavior and predation risk of mainland and island spiny-tailed iguanas "(Ctenosaura hemilopha")" "Ethology" 103(12): 990-998
*Rodda, G. "et al" (2002) "Practical concerns with the eradication of island snakes" "Turning the tide: the eradication of invasive species (proceedings of the international conference on eradication of island invasives) (Occasional Paper of the IUCN Species Survival Commission No. 27. Veitch, C. R. and Clout, M.N., eds) [http://issg.appfa.auckland.ac.nz/database/species/reference_files/boiirr/Rodda.pdf]
*Delibes., M.& Blázquez, M.C. (1998) "Tameness of Insular Lizards and Loss of Biological Diversity" "Conservation Biology" 12(5) 1142-1143
*Bunin, J. & Jamieson, I. (1995) "New Approaches Toward a Better Understanding of the Decline of Takahe ("Porphyrio mantelli") in New Zealand" "Conservation Biology" 9(1):100-106