The Power And Importance of Eradicating Invasive Rats

In another powerful example of successful eradication programmes, two remote islands in the North Pacific witnessed something amazing.

Researchers returning to the Marshall Islands | Shaun Wolfe

For centuries, rats wreaked havoc on the ecosystems of Bikar Atoll and Jemo Islet, both part of the Marshall Islands. But a recent restoration effort successfully eradicated the invasive rodent populations, delivering rat bait via drones in 2024.

When researchers with the nonprofit Island Conservation returned a year later, they were startled to discover that native seabird populations had rebounded. "After only one year, the transformation is dramatic. A colony of 2,000 Sooty Terns, where there was previously none, were feeding hundreds of chicks," says Paul Jacques, a project manager with Island Conservation. Furthermore, thousands of native tree seedlings appeared where none had been the year prior. “[Species] that were undetectable before, because they were so suppressed by the rats, were reappearing,” he told CNN.

Sooty terns safely nesting | Credit: Paul Jacques

​The ripple effect extends beyond the animals themselves. With more seabirds come more guano droppings, returning vital nutrients to the soil, enriching plant life, and benefiting surrounding reefs, thus rebuilding the island’s food web. These restored natural resources are also renewing hope for local communities to sustain their hunting and gathering traditions.

The goal now? Keep the islands clear of rats with minimal involvement. “These islands are places to be left alone to regenerate by themselves,” said Jacques.

Other successful eradication programmes include Floreana in the Galápagos Islands which resulted in a bird species being seen for first time since Darwin, and when Lord Howe Island in Australia finished eradicating the entirety of their invasive rat and mouse populations, the recovery of the endemic-Australian ecosystem was near-immediate;