What is assisted migration?

THE GUAM KINGFISHER - ALSO KNOWN as the sihek - has been extinct in the wild since 1988 but was successfully introduced to Palmyra Atoll last year. However, they aren’t native to the island (which is roughly one-third of the way between Hawaii and American Samoa). With the invasive brown tree snake responsible for their decline still at large on Guam, the most feasible way to restore them to the wild was by moving them to an entirely new home. Though the project is young, it’s a high-profile example of a controversial conservation technique known as assisted migration.

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Assisted migration is the process of moving a species outside of its native range - usually because that range is too depleted for long-term survival as a result of climate change, fragmentation or invasive species. Occasionally, it’s done to benefit the recipient ecosystem, such as the introduction of Aldabra giant tortoises to an islet off Mauritius to manage plant populations after the Mauritius giant tortoise became extinct.

For some conservationists, the reluctance to suggest assisted migration is automatic. It’s considered by some to be “the ultimate meddling”, says Sarah Dalrymple, a member of the England Species Reintroduction Taskforce. But she points out that “humans have been moving things for millennia”. As habitat and climate crises worsen, she believes migration can be vital for the right species and it’s our “ethical responsibility to explore all options”.