‘Extinct’ snails return to the wild

Zookeepers have returned more than 5,000 Extinct-in-the-Wild and Critically Endangered tropical snails bred at conservation zoos across the world to their French Polynesian island homes - almost 30 years after they were wiped out by a human-introduced invasive species. 

Thousands of Partula snails reared at London and Whipsnade Zoos, the Royal Zoological Society of Scotland and St Louis Zoo, were carefully flown over 15,000km to the islands of Moorea and Tahiti earlier this month, for the largest reintroduction in history.

ZSL’s Curator of Invertebrates, Paul Pearce-Kelly, who coordinates the collaborative Partula conservation programme, said: “Despite their small size these snails are of great cultural, ecological and scientific importance – they're the Darwin’s finches of the snail world, having been researched for more than a century due to their isolated habitat providing the perfect conditions to study evolution.

“This collaborative conservation initiative is, without a doubt, helping to bring these species back from the brink of extinction and shows the conservation power of zoos to reverse biodiversity loss. With nature across the world increasingly under threat, these little snails represent hope for the world’s wildlife.”

This year’s conservation efforts saw eight species and sub-species reintroduced, which are classified as Extinct-in-the-wild, Critically Endangered or Vulnerable. Before making the two -day journey to the islands, the nocturnal snails, which measure 1-2cm in length, were individually marked with a dot of red UV reflective paint, meaning they will glow under UV torchlight to - help conservationists monitor the populations at night when they’re most active.

Partula snails - also known as Polynesian tree snails - eat decaying plant tissue and fungi, so play an important role in maintaining forest health. Returning them back to the wild enables us to start restoring the ecological balance in these islands.

Now on their way back from the brink of extinction thanks to the dedicated work of conservation zoos and the French Polynesian Government’s Direction de l'environnement, the snails were under imminent extinction threat in the 1980s and early 1990s, after the invasive predatory rosy wolf snail (Euglandina rosea) was introduced to rid the islands of a previously introduced alien species, the African giant land snail (Lissachatina fulica). Unfortunately, the predatory rosy wolf snail targeted the endemic snails instead, and across the region – many species were lost or left close to extinction shortly after the predator’s arrival.

The last few surviving individuals of several Partula species were rescued in the early 1990s by London and Edinburgh Zoos, in order to begin the international conservation breeding programme – a collaborations between 15 zoos which care for 15 species and sub-species, the majority of which have an Extinct-in-the-Wild Red List threat status. Combined with others already being studied at universities around the world, it was these individuals that formed the source group to begin re-populating the Islands.

Paul added: “After decades of work caring for these species in conservation zoos - and working with the Direction de l'environnement to prepare the islands for their return - we began releasing Partula snails back into the wild nine years ago. 

“Since then, we’ve reintroduced over 21,000 Partula snails to the islands, including 11 Extinct-in-the-wild species and sub-species: this year’s was the largest reintroduction so far, thanks to the incredible work of our international team efforts with collaborators, including mollusc specialist Dr Justin Gerlach of Peterhouse, University of Cambridge.”

The Partula snail reintroduction project is made possible due to funding from supporters including the Players of the People’s Postcode Lottery, who have enabled ZSL to continue this vital work and bring species back from the brink of extinction.

To explore the vital conservation work being carried out at London and Whipsnade Zoos - both of which are ZSL conservation zoos - head to www.whipsnadezoo.org and www.londonzoo.org.