Modelling the Effect of Fences on the Viability of Spatially Structured Populations of African Wild Dogs

  • Michael J. Somers
  • Markus Gusset
  • Fredrik Dalerum
Chapter

Abstract

Although fences often have positive effects by protecting land from urban sprawl, poaching or encroaching livestock, they may also have negative effects related to animal movement and demographics. The African wild dog (Lycaon pictus) is a large, group-living carnivore that has some of the largest home ranges recorded among terrestrial carnivores, and it also disperses over long distances. This species can therefore be expected to suffer from the negative effects of fences due to restricted movement. We used stochastic population models to investigate the effect of varying levels of fence penetrability on the viability of spatially structured wild dog populations. We evaluated the effect of fences in both a source–sink scenario, in which we assumed one large source population and several smaller sink populations, and a metapopulation consisting of a range of subpopulations of equal size. The demographic effects of fences were higher in the source–sink scenario than in the metapopulation scenario, unless all subpopulation connections in the metapopulation were fenced. Metapopulations were also more sensitive to the effect of fences if they had a large number of connections. Although our study showed that fences can have negative effects on the viability of spatially structured wild dog populations, conflicting empirical data from South Africa suggest that these conclusions may not apply to all management scenarios. We recognize that these conflicting data are caused by the relative effects of the strength of density-dependent population regulation inside of fences and the mortality rates outside of fenced areas. While acknowledging that we only considered the direct demographic effects of constraints in animal movements caused by fences, we suggest that large protected areas are still the best way to manage for viable populations of large carnivores in most situations.

Keywords

Canid 

Notes

Acknowledgements

We are grateful to Mark Boyce, Matt Hayward and Kyran Kunkel for helpful comments on this chapter.

References

  1. Akçakaya, H.R., Mills, M.G.L. & Doncaster, C.P. (2007) The role of metapopulations in ­conservation. In: Key topics in conservation biology (eds. Macdonald, D.W. & Service, K.), pp. 64–84. Oxford: Blackwell Publishing.Google Scholar
  2. Brachet, S., Olivieri, I., Godelle, B., Klein, E., Frascaria-Lacoste, N. & Gouyon, P.-H. (1999) Dispersal and metapopulation viability in a heterogeneous landscape. Journal of Theoretical Biology, 198, 479–495.PubMedCrossRefGoogle Scholar
  3. Creel, S. & Creel, N.M. (2002) The African wild dog: behavior, ecology, and conservation. Princeton, NJ: Princeton University Press.Google Scholar
  4. Cross, P.C. & Beissinger, S.R. (2001) Using logistic regression to analyze the sensitivity of PVA models: a comparison of methods based on African wild dog models. Conservation Biology, 15, 1335–1346.CrossRefGoogle Scholar
  5. Dalerum, F., Shults, B. & Kunkel, K. (2008) Estimating sustainable harvest in wolverine populations using logistic regression. Journal of Wildlife Management, 72, 1125–1132.CrossRefGoogle Scholar
  6. Dalerum, F., Cameron, E.Z., Kunkel, K. & Somers, M.J. (2009) Diversity and depletions in continental carnivore guilds: implications for prioritizing global carnivore conservation. Biology Letters, 5, 35–38.PubMedCrossRefGoogle Scholar
  7. Davies-Mostert, H.T., Mills, M.G.L. & Macdonald, D.W. (2009) A critical assessment of South Africa’s managed metapopulation recovery strategy for African wild dogs. In: Reintroduction of top-order predators (eds. Hayward, M.W. & Somers, M.J.), pp. 10–42. Oxford: Wiley-Blackwell.CrossRefGoogle Scholar
  8. Frankham, R. (2009) Genetic considerations in reintroduction programmes for top-order, terrestrial predators. In: Reintroduction of top-order predators (eds. Hayward, M. W. & Somers, M. J.), pp. 371–387. Oxford: Wiley-Blackwell.CrossRefGoogle Scholar
  9. Franklin, J.F. & Lindenmayer, D.B. (2009) Importance of matrix habitats in maintaining biological diversity. Proceedings of the National Academy of Sciences of the USA, 106, 349–350.PubMedCrossRefGoogle Scholar
  10. Gusset, M. (2010) The re-introduction of African wild dogs in South Africa. In: Global re-­introduction perspectives: additional case-studies from around the globe (ed. Soorae, P. S.), pp. 220–224. Abu Dhabi: IUCN/SSC Re-introduction Specialist Group.Google Scholar
  11. Gusset, M., Ryan, S.J., Hofmeyr, M., van Dyk, G., Davies-Mostert, H.T., Graf, J.A., Owen, C., Szykman, M., Macdonald, D.W., Monfort, S.L., Wildt, D.E., Maddock, A.H., Mills, M.G.L., Slotow, R. & Somers, M.J. (2008) Efforts going to the dogs? Evaluating attempts to re-­introduce endangered wild dogs in South Africa. Journal of Applied Ecology, 45, 100–108.CrossRefGoogle Scholar
  12. Gusset, M., Jakoby, O., Müller, M.S., Somers, M.J., Slotow, R. & Grimm, V. (2009) Dogs on the catwalk: modelling re-introduction and translocation of endangered wild dogs in South Africa. Biological Conservation, 142, 2774–2781.CrossRefGoogle Scholar
  13. Gusset, M., Stewart, G.B., Bowler, D.E. & Pullin, A.S. (2010) Wild dog reintroductions in South Africa: a systematic review and cross-validation of an endangered species recovery programme. Journal for Nature Conservation, 18, 230–234.CrossRefGoogle Scholar
  14. Hanski, I. (1998) Metapopulation dynamics. Nature, 396, 41–49.CrossRefGoogle Scholar
  15. Hayward, M.W. & Kerley, G.I.H. (2009) Fencing for conservation: restriction of evolutionary potential or a riposte to threatening processes? Biological Conservation, 142, 1–13.CrossRefGoogle Scholar
  16. Hayward, M.W. & Somers, M.J. (eds) (2009) Reintroduction of top-order predators. Oxford: Wiley-Blackwell.Google Scholar
  17. Kruuk, H. (2002) Hunter and hunted: relationships between carnivores and people. Cambridge: Cambridge University Press.Google Scholar
  18. McCarthy, M.A., Burgman, M.A. & Ferson, S. (1995) Sensitivity analysis for models of population viability. Biological Conservation, 73, 93–100.Google Scholar
  19. McCarthy, M.A., Burgman, M.A. & Ferson, S. (1996) Logistic sensitivity and bounds for extinction risks. Ecological Modelling, 86, 297–303.CrossRefGoogle Scholar
  20. Mills, M.G.L. (2005) Large carnivores and biodiversity in African savanna ecosystems. In: Large carnivores and the conservation of biodiversity (Ed. by Ray, J. C., Redford, K. H., Steneck, R. S. & Berger, J.), pp. 208–229. Washington, DC: Island Press.Google Scholar
  21. Newmark, W.D. (2008) Isolation of African protected areas. Frontiers in Ecology and the Environment, 6, 321–328.CrossRefGoogle Scholar
  22. Prevedello, J.A. & Vieira, M.V. (2010) Does the type of matrix matter? A quantitative review of the evidence. Biodiversity and Conservation, 19, 1205–1223.CrossRefGoogle Scholar
  23. Prugh, L.R., Hodges, K.E., Sinclair, A.R.E. & Brashares, J.S. (2008) Effect of habitat area and isolation on fragmented animal populations. Proceedings of the National Academy of Sciences of the USA, 105, 20770–20775.PubMedCrossRefGoogle Scholar
  24. Revilla, E. & Wiegand, T. (2008) Individual movement behavior, matrix heterogeneity, and the dynamics of spatially structured populations. Proceedings of the National Academy of Sciences of the USA, 105, 19120–19125.PubMedCrossRefGoogle Scholar
  25. Somers, M.J., Graf, J.A., Szykman, M., Slotow, R. & Gusset, M. (2008) Dynamics of a small re-introduced population of wild dogs over 25 years: Allee effects and the implications of sociality for endangered species’ recovery. Oecologia, 158, 239–247.PubMedCrossRefGoogle Scholar
  26. Spiering, P.A., Szykman Gunther, M., Somers, M.J., Wildt, D.E., Walters, M., Wilson, A.S. & Maldonado, J.E. (2011) Inbreeding, heterozygosity and fitness in a reintroduced population of endangered African wild dogs (Lycaon pictus). Conservation Genetics, 12, 401–412.CrossRefGoogle Scholar
  27. Thomas, C.D. (2000) Dispersal and extinction in fragmented landscapes. Proceedings of the Royal Society B, 267, 139–145.PubMedCrossRefGoogle Scholar
  28. Watling, J.I., Nowakowski, A.J., Donnelly, M.A. & Orrock, J.L. (2011) Meta-analysis reveals the importance of matrix composition for animals in fragmented habitat. Global Ecology and Biogeography, 20, 209–217.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Michael J. Somers
    • 1
  • Markus Gusset
    • 2
  • Fredrik Dalerum
    • 3
  1. 1.Centre for Wildlife Management, Centre for Invasion Biology, Mammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
  2. 2.Wildlife Conservation Research Unit, Department of ZoologyUniversity of OxfordOxfordUK
  3. 3.Centre for Wildlife Management, Mammal Research Institute, Department of Zoology and EntomologyUniversity of PretoriaPretoriaSouth Africa

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