Experimental Release of Endemic Partula Species , Extinct in the Wild , into a Protected Area of NaturaI Habitat on

Extinction of tree snails of the genus Partula on Moorea, following introduction of the predatory snail Euglandina rosea, has challenged conservation biology during years of successive captive breeding of small rescued populations. An experimental release of three Partula species into a predator-proof patch of native forest on Moorea was designed to test effectiveness of physical and chemical methods of predator exclusion and to evaluate behavior of animals bred for up to six generations in highly artificial environments. At the close of the experimental release, there had been multiple incursions of E. rosea, and too few Partula spp. remained to assess effects of captive breeding on ecological responses. However, results demonstrated the effectiveness of the exclosure under ideal maintenance and monitoring. Captive breeding methods were validated by reproduction and growth to sexual maturity in the wild as well as retention of genetic variability in the form of persistent color polymorphism in one species. THE ULTIMATE OBJECTIVE of captive breeding programs is the reintroduction of viable populations of endangered species into their natural habitats. Even thriving captive populations are susceptible to novel pathogens 1 Financial support was provided by the University of California at Berkeley, the John Spedan Lewis Foundation, Lloyd's Bank Charitable Trust, the Natural Environment Research Council, British Airways, the Zoological Society of London, the Bristol, Clifton and West of England Zoological Society, Durrell Wildlife Conservation Trust, Royal Zoological Society of Scotland, the John G. Shedd Aquarium, the Detroit Zoological Institute, Memphis Zoological Society, Henry Doody Zoological Gardens, Saint Louis Zoo, and the Birrningham Zoo. This is contribution no. 103 of University of California, Berkeley's Richard B. Gump South Pacific Research Station, Moorea, French Polynesia. Manuscript accepted 5 August 2003. 2 Conservation Programmes, Zoological Society of London, Regents Park, London, NWl 4RY, United Kingdom. 3 Invertebrate Conservation Unit, London Zoo, Zoological Society of London, Regents Park, London, NWl 4RY, United Kingdom. 4 Department of Integrative Biology, University of California, Berkeley, California 94720. 5 Department of Biology, University of Virginia, Gilmer Hall, Charlottesville, Virginia 22903-2477. Pacific Science (2004), vol. 58, no. 3:429-434 © 2004 by University of Hawai'i Press All rights reserved (Cunningham and Daszak 1998) and to changes in gene frequency in response to artificial culture conditions. The land snails of the genus Partula have been particularly hard hit by a series of extinctions in the wild (see Cowie 1992 and Hickman 1999 for reviews and references). Species on many Polynesian islands have been extirpated by the introduction of the predaceous land snail Euglandina rosea in an ill-advised attempt at the biological control of the giant African snail, Achatina futica. However, more than 30 species of Partula have been rescued and perpetuated in captive breeding populations in 18 zoos and laboratories throughout the world (Pearce-Kelly et al. 1997). Because E. rosea remains a threat in the wild, there is no question of direct reintroduction in the immediate future. Based on promising results of a release of captive-bred Partula spp. on native French Polynesian plants in the controlled conditions of a botanic garden (Pearce-Kelly et al. 1995), an experimental predator-proof forest reserve, first proposed by Clarke and Wells (1986), was constructed on the island of Moorea, Society Islands, French Polynesia (17 0 30' 5// S, 149 49' 5// W). The reserve was situated at 210m elevation in the Mareaito Valley, immediately below the Belvedere and the ridge connecting Mt. Tohiea