Advertisement

Biodiversity & Conservation

, Volume 10, Issue 2, pp 143–159 | Cite as

Extinction or survival: partulid tree snails in American Samoa

  • Robert H. Cowie
  • Robert P. Cook
Article

Abstract

Four partulid tree snail species are known from American Samoa. In 1998, we surveyed the recently established National Park (units on three islands: Tutuila, Tau, Ofu) and neighboring areas for partulids. On Tutuila, Samoana abbreviata, previously considered probably extinct, was extremely rare (15 snails seen); Samoana conica was more common (288 snails) but still rare; Eua zebrina was the most common (1102 snails), at one locality perhaps near its natural abundance. The species have similar distributions within the Park. All three have declined dramatically since the 1920s. Before 1980, when the predatory snail Euglandina rosea was introduced, habitat destruction, and perhaps rat predation and shell collecting, probably caused the decline. The Park provides protection to the Tutuila partulids by protecting habitat, although development is still a potential problem. But predation by E. rosea may yet cause their extinction. On Ofu (only outside the Park), 12 live Samoana thurstoni were found; 31 have now been recorded by western science. Also, an apparently robust population of E. zebrina, previously considered a Tutuila endemic, was found. Euglandina rosea is not on Ofu, so these populations are important remnants of the fauna. No partulids were found on Tau; none has ever been recorded there.

biological control Eua Mollusca Pacific Partulidae Samoana 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Civeyrel L andSimberloff D (1996) A tale of two snails: is the cure worse than the disease? Biodiversity and Conservation 5: 1231-1252Google Scholar
  2. Clarke B,Murray J andJohnson MS (1984) The extinction of endemic species by a program of biological control. Pacific Science 38(2): 97-104Google Scholar
  3. Cooke CM Jr andCrampton HE (1930) New species of Partula. Bernice P Bishop Museum Occasional Papers 9(11): 1-9Google Scholar
  4. Cowie RH (1992) Evolution and extinction of Partulidae, endemic Pacific island land snails. Philosophical Transactions of the Royal Society of London B 335: 167-191Google Scholar
  5. Cowie RH (1993) Why tree snails are becoming scarce in Samoa. Hawaiian Shell News 41(3): 1, 9Google Scholar
  6. Cowie RH (1996) Variation in species diversity and shell shape in Hawaiian land snails: in situ speciation and ecological relationships. Evolution 49(6) [issue for 1995]: 1191-1202Google Scholar
  7. Cowie RH (1997a) Pacific island land snails: relationships, origins, and determinants of diversity. In: Keast A andScott E Miller (eds) The Origin and Evolution of Pacific Island Biotas, New Guinea to Eastern Polynesia: Patterns and Processes, pp 347-372. SPB Academic Publishing, Amsterdam [printed date 1996]Google Scholar
  8. Cowie RH (1997b) Catalog and bibliography of the nonindigenous nonmarine snails and slugs of the Hawaiian Islands. Bishop Museum Occasional Papers 50: 1-66Google Scholar
  9. Cowie RH (1998a) Patterns of introduction of non-indigenous non-marine snails and slugs in the Hawaiian Islands. Biodiversity and Conservation 7(3): 349-368Google Scholar
  10. Cowie RH (1998b) Catalog of the nonmarine snails and slugs of the Samoan Islands. Bishop Museum Bulletin in Zoology 3:i-viii, 1-122Google Scholar
  11. Cowie RH andCook RP (1999) The distribution and abundance of land snails in the National Park of American Samoa, with particular focus on Partulidae. Cooperative National Park Resources Studies Unit, University of Hawaii at Manoa, Technical Report 125: i-iii, 1-143Google Scholar
  12. Crampton HE (1925) Studies on the variation, distribution, and evolution of the genus Partula. The species of the Mariana Islands, Guam and Saipan. Carnegie Institution of Washington Publication 228A: i-vii, 1-116, 14 pllGoogle Scholar
  13. Gould SJ (1991) Unenchanted evening. Natural History 9/91: 4-14Google Scholar
  14. Griffiths O, Cook A and Wells SM (1993) The diet of the carnivorous snail Euglandina rosea in Mauritius and its implications for threatened island gastropod faunas. Journal of Zoology 229: 79-89Google Scholar
  15. Hadfield MG (1986) Extinction in Hawaiian achatinelline snails. Malacologia 27(1): 67-81Google Scholar
  16. Hadfield MG, Miller Stephen E and Carwile AH (1993) The decimation of endemic Hawai'ian [sic] tree snails by alien predators. American Zoologist 33: 610-622Google Scholar
  17. Hopper DR and Smith BD (1992) Status of tree snails (Gastropoda: Partulidae) on Guam, with a resurvey of sites studied by H.E. Crampton in 1920. Pacific Science 46(1): 77-85Google Scholar
  18. IUCN (International Union for the Conservation of Nature and Natural Resources) (1996) 1996 IUCN Red List of Threatened Animals. IUCN, Gland, SwitzerlandGoogle Scholar
  19. Johnson MS,Murray J andClarke B (1993) The ecological genetics and adaptive radiation of Partula on Moorea. Oxford Surveys in Evolutionary Biology 9: 167-238Google Scholar
  20. Keating BH (1992) The geology of the Samoan Islands. In: Keating BH andBolton BR (eds) Geology and Offshore Mineral Resources of the Central Pacific Basin, pp 127-178. Springer, New YorkGoogle Scholar
  21. Miller SE (1993) Final Report on Surveys of the Arboreal and Terrestrial Snail Fauna of American Samoa. United States Department of the Interior, Fish and Wildlife Service, HonoluluGoogle Scholar
  22. Miller SE,Cowie RH,Smith BD andRojek N (1993) The decline of partulid snail populations in American Samoa. Species 20: 65Google Scholar
  23. Murray J,Murray E,Johnson MS andClarke B (1989) The extinction of Partula on Moorea. Pacific Science 42(3-4) [1988]: 150-153Google Scholar
  24. Solem A (1975) Final report. United States Office of Endangered Species contract 14-16-0008-873. Unpublished reportGoogle Scholar
  25. USFWS (United States Department of the Interior Fish and Wildlife Service) (1994) Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species. Federal Register 59(219): 58982-59028Google Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Robert H. Cowie
    • 1
  • Robert P. Cook
    • 2
  1. 1.Department of Natural SciencesBishop MuseumHonoluluUSA
  2. 2.National Park of American SamoaPago PagoUSA

Personalised recommendations