As the world faces an extinction crisis, islands offer hope for stemming the decline of global biodiversity and saving Endangered animals.

Although all the islands in the world make up only 5.3% of the Earth’s landmass, they are home to a wide array of different species making them hotspots of biodiversity. In addition to a plethora of wildlife, historically islands have been the leading site of animal extinctions.

One of the leading threats that island animals face is predation and competition by introduced, invasive mammals with 86% of extinctions on islands being linked to invasive species. Luckily, these epicenters of extinction are ideal for conducting conservation and restoration activities. The isolated nature of islands means that permanently removing invasive species is possible and research has shown that it is a highly effective conservation tool.

Anacapa Island

Today, the cliffs of Anacapa Island, located off the coast of California serve as prime nesting habitat for a variety of native and some highly threatened seabird species. Twenty years ago, this seabird haven was overrun by invasive rats which predated the seabird eggs and chicks, threatening global populations of the Scripps’s Murrelet.

Following the removal of invasive rats, Anacapa has thrived and so have the seabirds. Hatching success among the Murrelets is greater than 90%, compared to less than 20% when rats occupied the island. Cassin’s Auklets have also re-colonized the island. In 2011, Endangered Ashy Storm-petrels established nesting sites on the island for the first time ever. Securing nesting habitat for the Scripps’s Murrelet and the resulting population growth was enabled the species to avoid being listed as Endangered. While the Ashy Storm-petrel remains threatened by invasive species across much of its habitat, there is still hope for its recovery.

Focus on Islands

Stories like the recovery of Anacapa are abundant and serve as prime examples of the lasting impact invasive species removal can have on islands, but research also reveals the importance of restoring islands. Islands host 20% of global biodiversity and are home to 41% of the world’s Critically Endangered and Endangered vertebrates. Many of these species and island ecosystems are threatened by the presence of invasive species, but using scientifically proven techniques, it is possible to prevent extinctions and bolster global biodiversity.

Research published in 2019 indicates that nearly 10% of island extinctions can be prevented by restoring 169 islands. The 50 authors with more than 804 combined years of experience in conservation science determined it is feasible to begin to restore all these islands in the next 10 years. The eight highest priority islands will benefit 24 populations of 23 highly threatened species. As the world faces an extinction crisis, islands offer hope for stemming the decline of global biodiversity and saving Endangered animals.

Featured photo: Caterpillar hanging from a tree branch on Mona Island, one of the eight highest-priority island. Credit: Tommy Hall