Skip to main content

Rapid decline of the endemic giant land snail Archachatina bicarinata on the island of Príncipe, Gulf of Guinea

  • Martin Dallimer (a1) and Martim Melo (a2)

Terrestrial and freshwater molluscs are amongst the most threatened of all taxa, yet data exist on the distribution and status of only a small proportion of the species. Here we present the results of the first systematic survey of a terrestrial mollusc on the island of Príncipe in the Gulf of Guinea. Archachatina bicarinata has never been previously surveyed, despite being categorized as Vulnerable on the IUCN Red List and suffering from unregulated harvesting for food. We found that A. bicarinata is restricted to primary rainforest and its abundance and probability of occurrence increased as surveyed sites became less accessible. Additional anecdotal evidence from the observations of previous scientific expeditions, local guides and snail harvesters suggested that the species has suffered a dramatic decline in population size and distribution in recent years. We therefore recommend that immediate action be taken to prevent its imminent extinction on Príncipe. The collection of A. bicarinata from protected areas should be banned, as should commercial harvesting and sales. Subsistence collecting should be limited to larger individuals. Our data have been used to inform the management plans for the protected areas on Príncipe and São Tomé, and this should help to ensure the future of A. bicarinata on both islands.

Corresponding author
*Biodiversity and Macroecology Group, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK. E-mail
Hide All
Agbelusi E.A. & Ejidike B.N. (1992) Utilization of the African giant land snail Archachatina marginata in the humid area of Nigeria. Tropical Agriculture, 69, 8892.
Baillie J. (1999) One Month in the Forests of Príncipe. Http:// [accessed 5 January 2009].
Burnham K.P. & Anderson D.R. (2002) Model Selection and Multimodal Inference. Springer, New York, USA.
California Academy of Sciences (2001) Californian Academy of Sciences Gulf of Guinea Biodiversity Project. Http:// [accessed 5 January 2009].
Cameron R.A.D. (1998) Dilemmas of rarity: biogeographical insights and conservation priorities for land Mollusca. Journal of Conchology, Special Issue, 5159.
Coote T. & Loève É. (2003) From 61 species to five: endemic tree snails of the Society Islands fall prey to an ill-judged biological control programme. Oryx, 37, 9196.
Cowie R.H. & Cook R.P. (2001) Extinction or survival: partulid tree snails in American Samoa. Biodiversity and Conservation, 10, 143159.
Dallimer M. & King T. (2008) Habitat preferences of the forest birds on the island of Príncipe, Gulf of Guinea. African Journal of Ecology, 46, 258266.
Dallimer M., King T. & Atkinson R.J. (2009) Pervasive threats within a protected area: conserving the endemic birds of São Tomé, West Africa. Animal Conservation, 12, 209219.
Diniz A.C. & de Matos G.C. (2002) Carta de Zonagem Agro-Ecológica e da Vegetação de S. Tome e Principe: I Ilha de S. Tomé. Garcia de Orta, Ser Botanica, 15, 122.
Figueiredo E. (1994) Diversity and endemism of angiosperms in the Gulf of Guinea islands. Biodiversity and Conservation, 3, 785793.
Fontaine B., Gargominy O. & Neubert E. (2007) Priority sites for conservation of land snails in Gabon: testing the umbrella species concept. Diversity and Distributions, 13, 725734.
Gascoigne A. (1994a) The biogeography of land snails in the islands of the Gulf of Guinea. Biodiversity and Conservation, 3, 794807.
Gascoigne A. (1994b) The dispersal of terrestrial gastropod species in the Gulf of Guinea. Journal of Conchology, 35, 17.
Gascoigne A. (1995) A Lista Vermelha de Animais Ameaçados de São Tomé e Príncipe. ECOFAC, São Tomé, São Tomé and Príncipe.
Gascoigne A. (2004) São Tomé, Príncipe, and Annobon moist lowland forests. In Terrestrial Ecoregions of Africa and Madagascar: A Conservation Assessment (eds Burgess N., D’Amico Hales J., Underwood E. & Dinerstein E.), pp. 236238. Island Press, Washington, DC, USA.
Gascoigne A., Wojciechowski T. & Koo M. (2004) Gulf of Guinea Conservation Group: Maps. Http:// [accessed 16 November 2008].
IUCN (2008) 2008 IUCN Red List of Threatened Species. Http:// [accessed 5 January 2009].
Johnson J.B. & Ohmland K.S. (2004) Model selection in ecology and evolution. Trends in Ecology & Evolution, 19, 101108.
Jones P.J. & Tye A. (2006) The Birds of São Tomé and Príncipe with Annobón, BOU Checklist Series No. 22. British Ornithologists Union, Oxford, UK.
Lydeard C., Cowie R.H., Ponder W.F., Bogan A.E., Bouchet P., Clark S.A. et al. . (2004) The global decline of non-marine mollusks. BioScience, 54, 321330.
McCarthy M.A. & Possingham H.P. (2006) Active adaptive management for conservation. Conservation Biology, 21, 956963.
Memel J.D., Otchoumou A., Kouassi D.K. & Dosso H. (2008) Inventaire, potentiel et repartition des escargot terrestres d’une forêt tropicale humide de Côte d’Ivoire: le Parc National du Banco (PNB). Novapex, 9, 119127.
Myers N., Mittermeier R.A., Mittermeier C.G., da Fonseca G.A.B. & Kent J. (2000) Biodiversity hotspots for conservation priorities. Nature, 403, 853858.
Osemeobo G.J. (1992) Effects of land-use and collection on the decline of African giant snails in Nigeria. Environmental Conservation, 19, 153159.
R Development Core Team (2008) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. Http:// [accessed January 2009].
Raheem D.C., Naggs F., Preece R.C., Mapatuna Y., Kariyawasam L. & Eggleton P. (2008) Structure and conservation of Sri Lankan land-snail assemblages in fragmented lowland rainforest and village home gardens. Journal of Applied Ecology, 45, 10191028.
Tattersfield P. (1998) Patterns of diversity and endemism in East African land snails, and the implications for conservation. Journal of Conchology, Special Issue, 7786.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0030-6053
  • EISSN: 1365-3008
  • URL: /core/journals/oryx
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 2
Total number of PDF views: 6 *
Loading metrics...

Abstract views

Total abstract views: 160 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 12th December 2017. This data will be updated every 24 hours.