Notes From the Field: Siamese Crocodile Hatchlings

Paul Buzzard, Ph.D., is the director of conservation for the Detroit Zoological Society.

We are very happy to report that 10 Siamese crocodiles recently hatched at the Detroit Zoo and will soon be released into the wild in Cambodia. The Siamese crocodile is one of the most endangered species of crocodile in the world, and was thought to be functionally extinct in the wild until the year 2000, when a small population was found in the highlands of southwest Cambodia. Now a total of around 250 Siamese crocodiles are believed to remain in three sub-populations. But it is still necessary to bolster the wild population so it can be sustainable into the future.

With Siamese crocodiles at zoos, there is sometimes a concern that there has been previous mating with other crocodile species, but genetic testing of the Siamese crocodiles at the Detroit Zoo confirmed that they are genetically pure and could be included in the Siamese Crocodile Species Survival Plan (SSP). An SSP is a program of the Association of Zoos and Aquariums, which strives to manage and conserve species populations in zoos and aquariums to ensure the sustainability of healthy, genetically diverse, and demographically diverse populations.

When suitable areas are available within the natural habitat of a species, individuals from SSP programs can sometimes be returned to the wild. The young crocodiles from the Detroit Zoo will be raised for several months by an adult crocodile pair at the St. Augustine Alligator Farm Zoological Park in Florida while permits are arranged for them to be released into protected areas of Cambodia.

– Dr. Paul Buzzard

Notes from the Field: Saving the Partula Snail

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

For nearly three decades, the Detroit Zoological Society (DZS) has been breeding a species of Tahitian land snails called Partula nodosa in an off-exhibit area as part of a collaborative effort credited with saving the species from extinction. Recently, 100 of these snails were carefully packaged and delivered to Detroit Metropolitan Airport to embark on a very special trip, returning the species to the tropical island of Tahiti in the south Pacific.Partula Snail - Jennie Miller

Beginning in 1989 as a project with 115 Tahitian land snails of five different species, the DZS focused its efforts on one species, P. nodosa. At one point all the P. nodosa in the world lived at the Detroit Zoo. Our efforts and successful breeding of the snails resulted in the rescue and recovery of the species – currently there are 6,000 individuals living in North American zoos, all descendants from the Detroit Zoo’s original small group.

P. nodosa snails are interesting because along with other Partulid snails, they were once found across Tahiti and other south Pacific islands in a dazzling array of more than 125 different species. 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.

Partula Snail - Jennie MillerMuch of the Partulid snail diversity was lost however, 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.

Thankfully, before complete extinction, P. nodosa snails were placed at several zoos including the Detroit Zoo, where they’ve been maintained off-exhibit in a collaborative effort of the Bird, Reptile and Amphibian departments. Now that the captive population has grown sufficiently and a protected area has been established on Tahiti, we can officially say that this species has been saved.

– Paul Buzzard