Tiny tropical snail no longer extinct in the wild after 40-year effort involving University of Cambridge

After 40 years of dedication and collaboration, conservationists were delighted to discover a species of tropical tree snail they had reintroduced is no longer extinct in the wild.

They found adult Partula tohiveana that had been born in the wild in French Polynesia.

This year, the University of Cambridge’s Dr Justin Gerlach helped restore more than 6,000 of the snails to Moorea, their French Polynesian island home, as part of an annual reintroduction of zoo-bred ‘extinct in the wild’ and ‘critically endangered’ snail species, carried out through collaboration with zoos around the world.

During their work, the team found unmarked Partula tohiveana, which proves that previously reintroduced snails have successfully bred in the area.

Dr Gerlach, of Peterhouse, and an academic associate at the university's Museum of Zoology, said: “Discovering wild-born adult snails was a great moment. Very few animal species have been re-established back in the wild so this is a fantastic achievement for the programme – the fruit of a vast amount of work.”

It is the first invertebrate species where this has been achieved.

In the 1980s and early 1990s, the snails were threatened by the invasive rosy wolf snail (Euglandina rosea), introduced to control the African giant land snail (Lissachatina fulica). The predatory species targeted native snails instead, leading to the extinction or near-extinction of many Partula species across the region.

The last remaining individuals of several Partula species were rescued in the early 1990s, by London and Edinburgh Zoos, which launched an international conservation breeding programme with 15 zoos caring for 15 species and subspecies, most of which are classified as ‘extinct in the wild’.

The snails reared at the zoos, which are just 1cm or 2cm in length, and were individually counted and marked with a dot of red UV reflective paint.

The ‘snail varnish’ glows under UV torchlight, which helps conservationists in the field to spot and monitor the nocturnal snails in the dark.

They were then taken more than 15,000km at the beginning of September in a two-day journey to the islands of Tahiti, Moorea and Huahine,

London Zoo’s senior curator of invertebrates, Paul Pearce-Kelly, who leads the Partula conservation programme, said: “Though little, these snails have great cultural, scientific and conservation value. Partula snails have always been part of Polynesia’s rich cultural heritage and play an important role in the ecological health of their forest habitats. They’ve also been studied for over a century for the insights they give into how species evolve in isolated environments. Most recently, they’re providing a valuable conservation model for helping hundreds of endangered island species.

“After decades of caring for these species in conservation zoos and working with the Direction de l’environnement to prepare the islands, we started reintroducing Partula snails back into their lowland tropical forests almost 10 years ago.

“Since then, we’ve reintroduced over 30,000 snails, including 10 extinct-in-the-wild species and subspecies, with this year’s release being the largest so far, thanks to our international team and collaborators.”

The team will now begin the process of downlisting the snails from ‘extinct in the wild’ to ‘critically endangered’ on the IUCN’s Red List.