In 1959, voracious invasive rats were blamed for killing hundreds of white-faced storm petrels, a small seabird, on New Zealand’s Maria Island. In part to protect the birds, conservationists spread rat poison on the 2-hectare island, also known as Ruapuke. They didn’t intend to eradicate the rats but 5 years later were pleasantly surprised to discover that the rodents had disappeared, and the seabirds were safe.