Reintroducing ‘Extinct’ snails to the wild in French Polynesia

Ectotherm keepers at Bristol Zoological Society have joined forces with other conservation zoos from across Europe to breed and re-establish a population of not just one, but two, Extinct-in-the-Wild species of Partula snails on their French Polynesian Island home.

Over fifteen zoos are collaborating on this huge conservation effort to reintroduce a number of tropical tree snail species that were wiped out over 30 years ago by a non-native invasive species, the carnivorous rosy-wolf snail. Bristol Zoological Society is joining Royal Zoological Society of Scotland, Zoological Society of London (ZSL), Marwell Zoo, Whipsnade Zoo, Artis, Riga, Schwerin, and Wuppertal, which are all releasing different numbers and combinations of species to support populations both in the wild and for breeding programmes within zoos.

Bristol Zoological Society has transported two sub-species of Partula snails to ZSL this month, the Partula navigatoria, which will be joining other snails in preparation for release next year, and the Partula mirabilis, which will be transported over 15,000km with those from other zoos, for release on the French Polynesian islands.

Monitoring is extremely important when it comes to tracking the success of conservation and reintroduction programmes, so our team have painted each snail with UV paint as a tracking device to monitor their movements and survival. Each year we pick a different colour, last year we chose blue and this year it’s yellow. The team painted their shells in different locations depending on their life stage, on the first whorl for adults and the apex of the spire of the shell, the tip, for adolescents. This technique enables us to track their survival across many years when surveying out in the field where they were released, as well as monitor if, and how many, juveniles reach adulthood. This year we are also trialling a new topcoat to increase the length of time the paint remains on the shell.

Kerry Marcus, Senior Ectotherm Keeper at Bristol Zoological Society said: “Partula snails, also known as Polynesian tree snails, play an important role in maintaining tropical tree health in French Polynesia by recycling nutrients from plant debris.

“Since the project started back in 1986, over 21,000 individuals of 11 previously Extinct-in-the-Wild species of Partula snails have been reintroduced into the wild on four different islands in French Polynesia.

“It is fantastic to be a part of this conservation collaboration and to witness the positive impact the return of this important species has to a fragile forest ecosystem that relies on their survival.”

Partula snails are roughly the size of a grain of rice when born and can grow to about 2cm, the size of a fingernail. To ensure the delicate care and transportation of these species’ ambassadors, the snails are carefully placed in tissue and cardboard tubes for their 22-hour flight.

Here at Bristol Zoological Society we are very excited to be partnering with other conservation leaders as part of this initiative. As a conservation charity, we work in nine countries, across four continents, and direct 14 field conservation projects with 31 local partner organisations to conserve and protect some of the world’s most threatened species. Our contribution to coordinated breeding programmes and worldwide conservation successes has shown the impact our work has on species protection, habitat restoration, as well as community engagement in the UK, around the world, and with other conservation zoos.

We look forward to monitoring the progress of this project and hope to see the species thrive in the wild.

Find out more information about our important conservation work below.