14 September 2023
Thousands of Extinct-in-the-Wild tropical tree snails bred at British conservation zoos have been flown more than 15,000km, accompanied by a Whipsnade zookeeper - to be reintroduced to their French Polynesian island home.
Eight species of Partula snail, totalling 2,194, were bred at Whipsnade Zoo, London Zoo, Edinburgh Zoo and Bristol Zoo Project, as part of the collaborative Partula Snail Conservation Programme - coordinated by international conservation charity ZSL and French Polynesia’s Direction de l'environnement. Many of these species were wiped out in the wild, 30 years ago.
Whipsnade invertebrate specialist Tyrone Capel, who helped rear the tiny snails at ZSL’s conservation zoos, arrived on the island on Monday 4 September and has already released hundreds of the fingernail-sized animals onto the volcanic island of Moorea.
“Partula snails, when born, are roughly the size of a grain of rice and can grow to about 2cm, so you need to be very delicate with them,” he explained. “We packaged the snails carefully in tissue and carboard tubes for their 22-hour flight, and a few days later the team and I trekked three hours into the forests of Moorea to release more than 1,600 Moorean Partula snails into the wild.
“As you can imagine snail releases are very slow, but it was incredible to watch them gradually propel themselves up into their natural tree habitat. All the hard work getting them there was worth it for that moment.”
Since 2015, conservationists have reintroduced more than 24,000 Partula snails onto the French Polynesian islands, with each year’s release painted with a dot of a different coloured glow-in-the-dark animal-friendly ‘snail varnish’ - so that their individual progress can be monitored with the help of a UV torch light.
“As the sun started to set, we could see this year’s bright blue snail polish starting to glow in the trees above,” added Tyrone.
More than 550 remaining snails will be introduced to their new homes on the neighbouring islands of Huahine, and Tahiti over the next week. Alongside releasing the new snails, Tyrone will conduct night surveys alongside French Polynesian Environmental Department colleagues to track past breeding programmes outcomes.
“Hopefully we will see the bright red snail polish of previously released snails, sparkling above us in the trees, so we can track how they are faring. The snails live high up in the tree canopy, so they can be difficult to spot – but luckily, they’re most active at night and the glow-in-the-dark polish will reveal their whereabouts, with the help of a UV torchlight.”
Many species of Partula snail became extinct on the islands of French Polynesia in the 1990s after the carnivorous Rosy wolf snail (Euglandina rosea), was released onto the islands to help control the previously introduced giant African land snail - but the predator preferred the endemic Partula tree snails instead.
“When the Rosy wolf snails were released, there were around 120 different species of Partula snail thriving in French Polynesia and other Pacific islands, but these specialist snail hunters had a voracious appetite and set about wiping many Partula species off the islands.”
John Ewen, from ZSL’s Institute of Zoology explained how conservation zoos had done an incredible job in saving Partula snails from certain extinction and boosting their population.
“Without conservation zoos, species like these Partula snails wouldn’t exist. In the 1990s ZSL and other partners led expeditions to the islands to save several of the species, creating a conservation breeding programme to protect them. After 30 years of keeping them alive in conservation zoos and working with partners to make their island homes safe once more, we’ve been able to return them back into the wild. While it’s still early days all the signs are looking encouraging.”
Tyrone said the loss of these snail species in French Polynesia had a big cultural and ecological impact.
“Not only has it harmed the islands’ fragile forest ecosystem, as the snails are important vegetation recyclers, but the snails have also been a huge loss for Polynesian culture, as the snail shells were sustainably used in cultural artefacts.
“This makes it even more important for us to work towards creating healthy, self-sustaining populations of the many species of Partula snail on each island, and we’ll continue to release snails each year until we do.”
“This is the pinnacle of my career,” the snail specialist added. “When I was a child, I dreamt of helping to save a species from extinction - now that dream is becoming a reality.”
Christophe Brocherieux, Project Manager, Direction de l'environnement said “We are proud to be partners in this programme, which highlights the importance of not being discouraged and of persevering to realise successful conservation outcomes.”
Funding support and expertise for the reintroduction initiative has been provided by programme partners Beauval Nature Association and Woodland Park Zoo.