Tiny French Polynesian tree snails, just 2 millimeters long (less than a tenth of an inch), have boosted the last population of Partula faba snails in the world, Bristol Zoo Gardens, in the UK, said today.
“The species, known as Partula faba, which is endemic to the island of Raiatea, is extinct in the wild, and these last snails have recently been given to Bristol Zoo Gardens in a critical effort to help save the species from total extinction through conservation breeding,” the zoo said in a news statement.
Newborn Partula faba snail
Photo by Jenny Spencer, Bristol Zoo Gardens
Partula faba were originally found only on Raiatea and were recorded during the visit to French Polynesia by Captain Cook’s Endeavour in 1769, according to Bristol Zoo. Along with Partula otaheitana of Tahiti, Partula faba was the first Partula species to be described.
A species of cannibal snails introduced to Raiatea in the 1980s quickly ate the native Partula faba snails into extinction, but not before the last survivors were removed for safekeeping.
Conservationists rescued a group of Partula faba snails from the island in 1991 to be bred in the safety of captivity. The species has not been seen on the island since, the zoo said.
According to the International Union for the Conservation of Nature (IUCN), native partulid species began disappearing from Raiatea rapidly after the introduction of the carnivorous snail Euglandina rosea in the late 1980s, “By 1992 there were few left and no live wild individuals of this species were found during surveys in 1994 and 2000. Species from Raiatea is maintained in the international breeding program,” IUCN says on its Partula faba profile page.
The IUCN Red List of Endangered Species assess Partula faba as extinct in the wild.
Invertebrate experts are nurturing the Bristol Zoo colony of 88 snails in a custom-built, climate-controlled room in the zoo’s Bug World–“the only place in the world where these snails can now be found.” The group has now produced 15 offspring–a significant boost to efforts to save the species, the zoo said.
Photo courtesy of Bristol Zoo Gardens
“Tree snails are incredibly endangered, with Partula faba being one of the most endangered of them all–they really are on the edge of survival,” said Grier Ewins, one of the keepers who look after the rare snails.
Ewins added: “The great news however, is that this last remaining population of Raiatean tree snails has been steadily growing since we took them on.
“Working with these, and so many other rare animals at the zoo, is incredibly satisfying. To think that I am nurturing the entire global population of these snails, and encouraging them to breed, is very rewarding–as well as a huge responsibility!
“It shows just how important the role of zoos and other conservation organisations are in helping to breed and protect endangered species, otherwise we risk losing many species forever, which would be a tragedy for us and future generations of people.”
French Polynesian tree snails were extirpated on Raiatea in part by the invasive snails introduced to the islands in the 1970s. Between the mid 1970s and mid 1990s an estimated 80 per cent of tree snail species were lost, Bristol Zoo said. “Loss of habitat, due to highly invasive plants such as the South American velvet tree, is also changing the landscape of the islands and adversely affecting the wildlife.”
Currently twenty Partula species have been saved from extinction by zoos and Universities; fifteen are classified as extinct in the wild and five are critically endangered. Five species of Polynesian tree snail are being kept at Bristol Zoo, all of which are part of an international captive breeding program to save the species.
Bristol Zoo’s Curator of Invertebrates, Warren Spencer, explained his hopes for the future of the snail species. “Although Raiatean tree snails are extinct in the wild, Bristol Zoo hopes to work with its conservation partners to release some snails into safe ‘zones’–reserves–back on the island of Raiatea and then to the surrounding area of a new reserve,” he said. “However, this can only be done once we have successfully removed or controlled the spread of the predatory ‘cannibal snail’ which was responsible for this species’ extinction.”
Bristol Zoo also breeds other animal species which are extinct in the wild, such as the Socorro dove, butterfly splitfin fish, golden sawfin fish and Potosi pupfish–which was successfully bred last year.
Other critically endangered animals which Bristol Zoo breeds include western lowland gorilla, Indochinese box turtle, Annam leaf turtle and Egyptian tortoise, as well as numerous mammal, bird, fish, invertebrate and amphibian species.