Henderson Island rats survived a 75-tonne poison campaign and rebounded within two years

Henderson Island (Image credit: Canva) In 2011, Henderson Island, a remote and uninhabited island in the South Pacific, became the site of one of the largest rodent-eradication attempts ever undertaken on an island of its size. Conservationists spread about 75 tonnes of poisoned bait across the island in an effort to eliminate invasive Pacific rats, which had been preying on native wildlife for generations. Yet the operation did not achieve its ultimate goal. According to research published in Bird Conservation International, a small number of rats survived the campaign, and their population recovered with remarkable speed. Within two years, rat numbers had recovered dramatically, highlighting how even a seemingly successful operation can unravel when a few animals remain behind.A remote island under pressureHenderson Island is a small, isolated coral island in the Pitcairn Islands group and is internationally important for its wildlife. Several land-bird species found there occur nowhere else in the world. But the island's ecosystem has long faced pressure from Pacific rats (Rattus exulans), which are believed to have arrived with Polynesian visitors centuries ago.The rats feed on...