Biodiversity & Conservation

, Volume 10, Issue 6, pp 1011–1026 | Cite as

Human density as an influence on species/area relationships: double jeopardy for small African reserves?

  • A.H. Harcourt
  • S.A. Parks
  • R. Woodroffe


Small reserves are especially likely to lose species. Is that because the reserves are small, or because small reserves are located in especially adverse landscapes? It seems that the question has rarely, if ever, been asked. Data on reserve size and location in Africa, and calculations of local (within 50 km) mean human densities from available census records per province per country were the database here used to answer the question. IUCN grade I and II reserves in Africa are located across the range of human densities per country, including in regions of higher than average density. Furthermore reserve size correlates with local human density, such that small reserves are indeed significantly more likely than are large reserves to be located in regions of high human density (n = 169; P < 0.0001). However, while local human density correlates significantly with human-caused mortality of carnivores (the only taxon for which we had data), it does not correlate with detected extinctions in reserves in east Africa (the only region with available data). Rather, area of reserve is the main predictor. Nevertheless, abundant other evidence of the adverse effects of high human density on persistence of species and wilderness indicates that we need to take as a warning the findings reported here that small reserves occur in regions of high human density, and that human density correlates with human-caused mortality. They indicate that small reserves might face the double jeopardy of both their small size, and also their situation in especially hostile surroundings. In effect, small reserves are more isolated in more adverse habitat than current analyses in conservation biology, landscape ecology, or metapopulation analysis usually indicate.

Africa edge effects extinction human density protected areas species/area relationships 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Andrén H (1995) Effects of landscape composition on predation rates at habitat edges. In: Hansson L,Fahrig L andMerriam G (eds) Mosaic Landscapes and Ecological Processes, pp 225-255. Chapman & Hall, LondonGoogle Scholar
  2. Ayres JM,Bodmer RE andMittermeier RA (1991) Financial considerations of reserve design in countries with high primate diversity. Conservation Biology 5: 109-114Google Scholar
  3. Barnes RFW (1990) Deforestation trends in tropical Africa. African Journal of Ecology 28: 161-173Google Scholar
  4. Bawa KS andDayanandan S (1997) Socioeconomic factors and tropical deforestation. Nature 386: 562-563Google Scholar
  5. Belovsky GE (1987) Extinction models and mammalian persistence. In: Soulé ME (ed) Viable Populations for Conservation, pp 35-57. Cambridge University Press, CambridgeGoogle Scholar
  6. Brooks T andBalmford A (1996) Atlantic forest extinctions. Nature 380: 115Google Scholar
  7. Brooks TM,Pimm SL andCollar NJ (1997) Deforestation predicts the number of threatened birds in insular Southeast Asia. Conservation Biology 11: 382-394Google Scholar
  8. Brown JH (1971) Mammals on mountaintops: nonequilibrium insular biogeography. American Naturalist 105: 467-478Google Scholar
  9. Burkey TV (1995) Faunal collapse in East African game reserves revisited. Biological Conservation 71: 107-110Google Scholar
  10. Cowlishaw G (1999) Predicting the pattern of decline of African primate diversity: an extinction debt from historical deforestation. Conservation Biology 13: 1183-1193Google Scholar
  11. Cox DR (1970) The Analysis of Binary Data. Methuen, LondonGoogle Scholar
  12. Debinski DM andHolt RD (2000) A survey and overview of habitat fragmentation experiments. Conservation Biology 14: 342-355Google Scholar
  13. Diamond JM (1975) The island dilemma: lesson of modern biogeographic studies for the design of natural reserves. Biological Conservation 7: 129-146Google Scholar
  14. Diamond JM (1984) 'Normal' extinctions of isolated populations. In: Nitecki MH (ed) Extinctions, pp 191-246. University of Chicago Press, ChicagoGoogle Scholar
  15. ESRI Inc. (1998a) ARC/INFO, 7.1.2. Environmental Systems Research Institute, Inc., Redlands, CaliforniaGoogle Scholar
  16. ESRI Inc. (1998b) ArcView GIS, 3.1. Environmental Systems Research Institute, Inc., Redlands, CaliforniaGoogle Scholar
  17. Hannah L,Lohse D,Hutchinson C,Carr JL andLankerani A (1994) A preliminary inventory of human disturbance of world ecosystems. Ambio 23: 246-250Google Scholar
  18. Hanski IA andGilpin ME (eds) (1997) Metapopulation Biology. Ecology, Genetics, and Evolution. Academic Press, San Diego, CaliforniaGoogle Scholar
  19. Hansson L,Fahrig L andMerriam G (eds) (1995) Mosaic Landscapes and Ecological Processes. Chapman & Hall, LondonGoogle Scholar
  20. Harcourt AH (1981) Can Uganda' gorillas survive? A survey of the Bwindi Forest Reserve. Biological Conservation 19: 269-282Google Scholar
  21. Harcourt AH (1996) Is the gorilla a threatened species? How should we judge? Biological Conservation 75: 165-176Google Scholar
  22. Harcourt AH (1998) Ecological indicators of risk for primates, as judged by susceptibility to logging. In: Caro TM (ed) Behavioral Ecology and Conservation Biology, pp 56-79. Oxford University Press, New YorkGoogle Scholar
  23. Harcourt AH andSchwartz MW (2001) Primate evolution: a biology of Holocene extinction and survival on the South-East Asian Sunda Shelf Islands. American Journal of Physical Anthropology 114: 4-17Google Scholar
  24. Heaney LR (1984) Mammalian species richness on islands on the Sunda Shelf, southeast Asia. Oecologia 61: 11-17Google Scholar
  25. Hoare RE andDu Toit JT (1999) Coexistence between people and elephants in African savannas. Conservation Biology 13: 633-639Google Scholar
  26. Hunter ML and Yonzon P (1993) Altitudinal distributions of birds, mammals, people, forests, and parks in Nepal. Conservation Biology 7: 420-423Google Scholar
  27. Iremonger S,Ravilious C andQuinton T (eds) (1997) A Global Overview of Forest Conservation CD-ROM. WCMC and CIFOR, Cambridge, UKGoogle Scholar
  28. IUCN (1996) 1996 IUCN Red List of Threatened Animals. IUCN, Gland, SwitzerlandGoogle Scholar
  29. Jablonski D (1991) Extinctions: a paleontological perspective. Science 253: 754-757Google Scholar
  30. Jernvall J andWright PC (1998) Diversity components of impending primate extinctions. Proceedings of the National Academy of Sciences, USA 95: 11 279-11 283Google Scholar
  31. Johns AD andSkorupa JP (1987) Responses of rain-forest primates to habitat disturbance: a review. International Journal of Primatology 8: 157-191Google Scholar
  32. Kerr JT andCurrie DJ (1995) Effects of human activity on global extinction risk. Conservation Biology 9: 1528-1538Google Scholar
  33. Laurance WF (1990) Comparative responses of five arboreal marsupials to tropical forest fragmentation. Journal of Mammalogy 71: 641-653Google Scholar
  34. Laurance WF (1991) Ecological correlates of extinction proneness in Australian tropical rain forest mammals. Conservation Biology 5: 79-89Google Scholar
  35. Laurance WF andBierregaard RO (eds) (1997) Tropical Forest Remnants. University of Chicago Press, ChicagoGoogle Scholar
  36. Leach MK andGivnish TJ (1996) Ecological determinants of species loss in remnant prairies. Science 273: 1555-1558Google Scholar
  37. Leader-Williams N andAlbon SD (1988) Allocation of resources for conservation. Nature 336: 533-535Google Scholar
  38. Leader-Williams N,Harrison J andGreen MJB (1990) Designing protected areas to conserve natural resources. Science Progress Oxford 74: 189-204Google Scholar
  39. Lomolino MV,Brown JH andDavis R (1989) Island biogeography of montane forest mammals in the American Southwest. Ecology 70: 180-194Google Scholar
  40. MacArthur RH (1972) Geographical Ecology. Patterns in the Distribution of Species. Princeton University Press, PrincetonGoogle Scholar
  41. McNeely JA,Gadgil M,Levèque C,Padoch C andRedford K (1995) Human influences on biodiversity. In: Heywood VH andWatson RT (eds) Global Biodiversity Assessment, pp 711-821. Cambridge University Press, CambridgeGoogle Scholar
  42. Mittermeier RA,Myers N,Thomsen JR,da Fonseca GAB andOlivieri S (1998) Biodiverity hotspots and major tropical wilderness areas: approaches to setting conservation priorities. Conservation Biology 12: 516-520Google Scholar
  43. Muchaal PK andNgandjui G (1999) Impact of village hunting on wildlife populations in the western Dja Reserve, Cameroon. Conservation Biology 13: 385-396Google Scholar
  44. Myers N,Mittermeier RA,Mittermeier CG,da Fonseca GAB andKent J (2000) Biodiversity hotspots for conservation priorities. Nature 403: 853-858Google Scholar
  45. Naveh Z andLieberman AS (1994) Landscape ecology: theory and application, 2nd edn. Springer-Verlag, New YorkGoogle Scholar
  46. Newmark WD (1995) Extinction of mammal populations in western American national parks. Conservation Biology 9: 512-526Google Scholar
  47. Newmark WD (1996) Insularization of Tanzanian parks and local extinction of large mammals. Conservation Biology 10: 1549-1556Google Scholar
  48. Parker ISC andGraham AD (1989) Men, elephants, and competition. Symposia of the Zoological Society of London 61: 241-252Google Scholar
  49. Pimm SL (1991) The Balance of Nature. University of Chicago Press, ChicagoGoogle Scholar
  50. Robinson JG,Redford KH andBennett EL (1999) Wildlife harvest in logged tropical forests. Science 284: 595-596Google Scholar
  51. Rosenzweig ML (1995) Species Diversity in Space and Time. Cambridge University Press, CambridgeGoogle Scholar
  52. SAS Institute Inc. (1995) JMP, 3.2.2. SAS Institute Inc., Cary, North CarolinaGoogle Scholar
  53. Sokal RR andRohlf FJ (1981) Biometry. The Principles and Practice of Statistics in Biological Research. W.H. Freeman and Co., San FranciscoGoogle Scholar
  54. Soulé ME,Wilcox BA andHoltby C (1979) Benign neglect: a model of faunal collapse in the game reserves of East Africa. Biological Conservation 15: 259-272Google Scholar
  55. Terborgh J (1974) Preservation of natural diversity: the problem of extinction prone species. Bioscience 24: 715-722Google Scholar
  56. Turner IM (1996) Species loss in fragments of tropical rain forest: a review of the evidence. Journal of Applied Ecology 33: 200-209Google Scholar
  57. Van Vuren D (1998) Mammalian dispersal and reserve design. In: Caro TM (ed) Behavioral Ecology and Conservation Biology, pp 369-393. Oxford University Press, New YorkGoogle Scholar
  58. Western D andSsemekula J (1981) The future of the savanna ecosystems: ecological islands or faunal enclaves? African Journal of Ecology 19: 7-19Google Scholar
  59. Wiens JA (1997) Metapopulation dynamics and landscape ecology. In: Hanski IA andGilpin ME (eds) Metapopulation Biology. Ecology, Genetics and Evolution, pp 43-62. Academic Press, San Diego, CaliforniaGoogle Scholar
  60. Wilcox BA (1980) Insular ecology and conservation. In: Soulé ME andWilcox BA (eds) Conservation Biology. An Evolutionary-Ecological Perspective, pp 95-117. Sinauer, Sunderland, Massachusetts, USAGoogle Scholar
  61. Wilson EO andWillis EO (1975) Applied biogeography. In: Cody ML andDiamond JM (eds) Ecological Structure of Species Communities, pp 522-534. Harvard University Press, CambridgeGoogle Scholar
  62. Woodroffe R andGinsberg JR (1998) Edge effects and the extinction of populations inside protected areas. Science 280: 2126-2128Google Scholar
  63. World Resources Institute (1995) Africa Data Sampler CD. World Resources Institute, Washington, DCGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • A.H. Harcourt
    • 1
  • S.A. Parks
    • 1
  • R. Woodroffe
    • 2
  1. 1.Department of AnthropologyUniversity of CaliforniaDavisUSA
  2. 2.Ecology and Epidemiology Group, Department of Biological SciencesUniversity of WarwickCoventryUK

Personalised recommendations