Polynesia: Partula Snail

Throughout most of the last century, visiting biologists studied a remarkable example of species radiation - a genus of tree snails (numbering over 120 species) called Partula, provided unique insights into evolutionary genetics.

However by the end of the 20th century, the number of species surviving on the Society Islands had been reduced from 61 to just 5. The cause of these catastrophic extinctions was a misguided attempt at biological pest control.

The predatory snail Euglandina rosea introduced in the 1970s to combat an earlier introduction of the African giant land snail Achatina fulica, which had become an agricultural pest. Euglandina devoured the native Partula snails.

Drastic action to save Partula species

This extinction crisis sparked the International Partula Conservation Programme (co-ordinated by ZSL since 1994) to be set up. This involves a managed breeding programme for 25 species in 15 collaborating zoos worldwide, together with extensive work in the species natural range areas with local conservationists and government agencies. The field focus concentrates on studying the population dynamics of native and alien species and the establishment of predator-exclusion structures in forest.

The recently completed Partula reserve on Tahiti is protecting populations of the last 5 surviving species in the Society Islands. Other reserves will provide a mechanism to reintroduce Partula species using populations from the breeding programme. Hopefully, soon some individuals that have been bred in the Snail Room at London Zoo will be able to be reintroduced there.

The latest initiative is a collaboration between ZSL, the French Polynesian Government and local communities to develop a biodiversity conservation strategy for the region.

The new reserve is only small, but, then again, so are the snails. The important thing is that it is completely protected from predators and disturbance.