Anonymous Island in the Seychelles. Credit: James Russell

What's the biggest alien threat to islands?

Embargoed until: Publicly released:

Islands are particularly vulnerable to invasions by alien species, and Kiwi scientists have now defined the 15 top invaders worldwide. While Marvin and Spock don't quite make the list, rodents, ants and mosquitoes dominate because of their impacts on native flora and fauna. However, invasive plants make up the majority of the most prevalent invasive species on islands. More than 2,000 invasive species have been documented, but these 15 top invaders are particularly dangerous because of their spread and prevalence across the world.

Journal/conference: Environmental Conservation

Link to research (DOI): 10.1017/S0376892917000297

Organisation/s: University of Auckland

Funder: James Russell was funded by Rutherford Discovery Fellowship grant RDF-UOA1404. The Global Register of Introduced and Invasive Species (GRIIS) has been developed with co-funding from the EuropeanUnion through the Secretariat of the Convention on Biological Diversity (CBD) within the framework of the Global Invasive Alien Species Information Partnership (GIASIP).

Media Release

From: University of Auckland

List of top alien species invaders on islands

Researchers have listed the top 15 alien species invaders most commonly found on islands around the world and their impacts on native flora and fauna.

Using data from the Global Register of Introduced and Invasive Species, the scientists documented over 2,000 invasive species, but showed that most of these are only found on a few islands, while only a few were globally widespread. The study included 33 island nations.

Invasive plants make up the majority of the top fifteen list of the most prevalent invasive species on islands although rodents, ants and mosquitos also featured prominently.

The study, led by Senior Lecturer James Russell of the University of Auckland’s School of Biological Sciences, provides the first synthesis of the impacts and distribution of the many invasive species found on islands globally.

“Islands such as New Zealand have long been known to be vulnerable to the impact of invasive species introduced to them, the classic example being the introduction of mammalian predators driving many bird species to extinction,” he says.

“However, although every island in the world fights its own battles against invasive species, this study provides a global overview of trends in the impact and distribution of invasive species across all islands for the first time.”

The researchers investigated the interactions of these invasive species with other global change stressors such as agricultural intensification, urbanisation and climate change.

However, they end optimistically by concluding with a summary of the current status of invasive species management on islands, focusing on when it may be possible to eradicate some invasive species, such as New Zealand’s ambitious Predator Free 2050 campaign.

Study co-author Dr Nick Holmes from the Island Conservation NGO says invasive species are a key threat to plant, animal and human communities dependent on islands.

“But there is hope. There are many examples of invasive species prevention, control and eradication leading to positive conservation outcomes. We should strive to replicate these successes, and improve our knowledge of how to tackle bigger challenges on islands across the globe.”

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