New Zealand removed 200,000 mice from an island; native bird populations more than doubled

The team used helicopters to spread cereal bait containing the rodent toxin brodifacoum (Picture: Mouse free marion) In 2016, New Zealand launched a major operation to remove an estimated 200,000 mice from the remote Antipodes Island. The mice were the only mammalian pest species on the island, but their impact on the ecosystem was significant.According to the country's department of conservation, the mice were eating large numbers of invertebrates and plant seeds. They were also competing with native birds for food and were known to eat the eggs and chicks of seabirds. On Antipodes Island, their presence had contributed to a lack of invertebrates compared with nearby islands without mice.The operation was completed as planned, and in 2018, monitoring confirmed that the mice had been eradicated. The story did not end with the removal of the pests. Surveys carried out over the following six years showed native bird populations beginning to recover, with the numbers of Antipodes Island pipit and snipe more than doubling. The results were published in thw New Zealand Journal of Ecology.Why mice were a problemAntipodes Island is part of New Zealand's subantarctic islands. The mice were...