Notes from the Field: Detroit Zoo Continues to Save Once-Extinct Snail Species

The Detroit Zoological Society (DZS) is continuing to bolster the wild population of a species of Tahitian land snail called Partula nodosa, which we are credited with saving from extinction. At one point, all the P. nodosa in the world lived at the Detroit Zoo as part of a breeding program that began in 1989 after the species had been declared extinct in the wild. Last summer, 100 of these snails were carefully packaged before embarking on a journey to the tropical island of Tahiti. Last month, an additional 60 snails began their voyage, departing the Detroit Zoo on a path first to the Netherlands before their eventual release into the wilds of the South Pacific.

P. nodosa were once found across Tahiti and other south Pacific islands among more than 125 different species of land snails. These beautifully striped snails were important in the ceremonial jewelry and decorations of native islanders, and the snails served as an ideal study group to learn more about the evolution of diversity.

Much of the Partulid snail diversity was lost because of a botched attempt at what is known as “biological control”, or the control of a pest by the introduction of a natural enemy or predator. In 1967, giant African land snails were introduced to Tahiti and other south Pacific islands to serve as a source of protein for local people. However, some African snails escaped, bred very rapidly, and began eating farmers’ crops, threatening the local economy. To control the African snails, Florida rosy wolf snails were introduced a decade later, but the wolf snails preferred to eat the Partulid snails, which caused the extinction of many of the Partulid species.

For nearly three decades, the DZS has been breeding these snails in a behind-the-scenes area as part of a collaborative effort with other zoos. The project began in 1989 with 115 Tahitian land snails of five different species – while the DZS focused its efforts on P. nodosa, other zoos began working on the others. Our program led to the rescue and recovery of the species – currently there are 4,000 individuals living in North American zoos, all descendants from the Detroit Zoo’s original small group.

Paul Buzzard, Ph.D., is the Director of Conservation for the Detroit Zoological Society.

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