Invasive Species
Islands occupy approximately three percent of the earth’s surface but provide key habitat for 15 to 20 percent of all plant, reptile and bird species. Islands are also characterized by a high rate of species endemism.
Approximately 70 percent of confirmed animal extinctions have been island species, and most of these extinctions were the result of invasive species. At present, more than half of all International Union for Conservation of Nature (IUCN) red-listed avifauna are threatened by invasive species.
Invasive species are non-native flora and fauna that outcompete native species when introduced outside of their natural environment and threaten native ecosystems. Invasive species generally share common characteristics which can make them difficult to control and contain. These characteristics include higher rates of reproduction, fewer natural predators and the ability to thrive in different environments.
Invasive species do damage by:
- negatively impacting biodiversity
- competing with native species until they become threatened, endangered, extirpated or extinct
- degrading and eroding soil
- degrading water and habitats
Like a ripple in a pond, their impact is far-reaching…
Biological invasions on islands resulting from the introduction of non-native invasive species are a major driver of biodiversity loss which not only affects native plant and wildlife species, but also human economy, health and ecosystem services provided by intact systems.
Introduced vertebrate species such as rats, mink, and raccoon have dramatically altered ecological processes on many of the world’s islands, including sites that support some of the largest assemblages of breeding seabirds. These invasive species prey on adult seabirds and their offspring, ultimately disrupting the nutrient transfer cycle from sea to land. These changes, in turn, can impact the entire island ecosystem.
In addition to invasive mammalian species, introduced predatory amphibians and fish can also have detrimental effects on aquatic ecosystems including impacts to native fish, amphibians, invertebrates, and vegetation through habitat alteration, predation, competition, disease, and gene pool deterioration.
Similarly, introduced herbivores can have strong effects on island ecosystems including the loss of native plants and plant communities. Browsing and grazing pressure by introduced species such as deer, goats and pigs can also effects at multiple trophic levels leading to impacts on all island species from insects to top predators.
Invasive species eradication – A powerful conservation tool to protect biodiversity
In response to these biodiversity threats, techniques have been developed and improved over the past 30 years to eradicate introduced species from islands. Invasive species eradication projects have been successful on many islands around the world resulting in the long-term protection of native species. This conservation measure is now considered to be one of society’s most powerful tools for preventing extinctions and restoring ecosystems.
To date, 1,182 whole-island introduced invasive species eradication projects have occurred or are in process on 762 individual islands (Database of Invasive Species Eradications 2012).
The Island Conservation Database of Island Invasive Species Eradications compiles all of the historical and current invasive vertebrate eradications on islands. Data from each project includes information on the island, methods used in the eradication and contact information for people knowledgeable about the eradication. Click here to learn more about island restoration projects near you!
