PREVIEW

A rare species of Polynesian tree snail once believed to be extinct in the wild has been officially reclassified as critically endangered, following a decades-long conservation effort led by ZSL, the charity behind London Zoo, and its global partners.

The Partula tohiveana snail, which was wiped out in the wild due to the introduction of predatory carnivorous snails, has been downlisted from Extinct in the Wild to Critically Endangered by the International Union for Conservation of Nature (IUCN) Red List. The decision follows the success of a reintroduction programme in French Polynesia.

Last year, conservationists made a significant breakthrough when they discovered wild-born adult Partula tohiveana in Moorea, confirming that the species is not only surviving but reproducing in its natural habitat.

The snails were part of carefully managed annual reintroductions led by London Zoo, in collaboration with the French Polynesian Government, the University of Cambridge, and a network of international conservation organisations.

David Field, CEO of the Royal Zoological Society of Scotland (RZSS), described the downlisting as "an incredible milestone in the story of the Partula tohiveana snail."

He added: "To take the species from the edge of extinction and boost their population in the wild is a fantastic achievement. With our planet facing a biodiversity crisis, this highlights the crucial and unique role zoos play in wildlife conservation. In our 2030 strategy, we pledged to help reverse the decline of 50 species by the end of the decade, so we are thrilled to see our efforts to save the Partula tohiveana are a success, thanks to the collaboration of conservation zoos."

ZSL first began breeding Partula snails in the 1980s after their populations were decimated by the invasive rosy wolf snail (Euglandina rosea). Conservationists cared for and bred the snails in controlled environments at London Zoo and other facilities worldwide, before reintroducing them to their native forests in French Polynesia. Each snail was carefully marked with UV reflective paint to monitor their progress in the wild.

Paul Pearce-Kelly, Senior Curator of Invertebrates at London Zoo, called the development "a landmark moment for Partula tohiveana and for decades of international conservation work."

He said: "Seeing a species return from the brink after years of collaborative effort is exactly why we do what we do. This inspiring news shows our real-world impact and how we are bringing some of the most vulnerable species back from the brink of extinction. As ZSL approaches its 200th anniversary next year, this is a fantastic success for our longest-running conservation project."

The reintroduction of the snails is part of a broader conservation initiative known as the Extinct in the Wild Alliance, a collaboration between zoos and conservation institutions aimed at restoring species that have disappeared from their natural habitats.

Dr Justin Gerlach of the University of Cambridge, who has led field releases in recent years, described finding the first wild-born snails as "an unforgettable moment."

He added: "Each time we have taken snails back to the forest, I have hoped we would find evidence of an established population. Now we need to build this population and replicate this success with other species. This is only the 13th time a species has been downlisted from Extinct in the Wild, and the first for an invertebrate. We hope to add more Partula species to that list."
The conservation effort has involved experts from institutions across Europe and North America, including Bristol Zoological Society, Detroit Zoological Society, Marwell Wildlife, Saint Louis Zoo, and Woodland Park Zoo.

The success of the Partula tohiveana programme serves as a beacon of hope for other species on the brink. Conservationists now plan to expand efforts to restore additional species of Partula snails in the wild, ensuring that these small but significant creatures continue to thrive.