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Oecologia

, Volume 158, Issue 2, pp 239–247 | Cite as

Dynamics of a small re-introduced population of wild dogs over 25 years: Allee effects and the implications of sociality for endangered species’ recovery

  • Michael J. SomersEmail author
  • Jan A. Graf
  • Micaela Szykman
  • Rob Slotow
  • Markus Gusset
Population Ecology - Original Paper

Abstract

We analysed 25 years (1980–2004) of demographic data on a small re-introduced population of endangered African wild dogs (Lycaon pictus) in Hluhluwe-iMfolozi Park (HiP), South Africa, to describe population and pack dynamics. As small populations of cooperative breeders may be particularly prone to Allee effects, this extensive data set was used to test the prediction that, if Allee effects occur, aspects of reproductive success, individual survival and population growth should increase with pack and population size. The results suggest that behavioural aspects of wild dogs rather than ecological factors (i.e. competitors, prey and rainfall) primarily have been limiting the HiP wild dog population, particularly a low probability of finding suitable mates upon dispersal at low pack number (i.e. a mate-finding Allee effect). Wild dogs in HiP were not subject to component Allee effects at the pack level, most likely due to low interspecific competition and high prey availability. This suggests that aspects of the environment can mediate the strength of Allee effects. There was also no demographic Allee effect in the HiP wild dog population, as the population growth rate was significantly negatively related to population size, despite no apparent ecological resource limitation. Such negative density dependence at low numbers indicates that behavioural studies of the causal mechanisms potentially generating Allee effects in small populations can provide a key to understanding their dynamics. This study demonstrates how aspects of a species’ social behaviour can influence the vulnerability of small populations to extinction and illustrates the profound implications of sociality for endangered species’ recovery.

Keywords

Allee effect Conservation Cooperative breeding Dispersal Lycaon pictus 

Notes

Acknowledgments

We thank The Green Trust (WWF–South Africa), The Endangered Wildlife Trust, Smithsonian National Zoological Park, Shirley Sichel and Abbott Endowment Funds, Friends of the National Zoo, Smithsonian Institution (Office of the Undersecretary for Science), British Airways, Third World Academy of Science, The Wild Dog Foundation, The Sally Club, The Wildlands Conservation Trust, DST–NRF Centre of Excellence for Invasion Biology, Ezemvelo KZN Wildlife, National Research Foundation and the University of KwaZulu-Natal for funding. We thank Ezemvelo KZN Wildlife and its staff (especially Dave Balfour, Sue van Rensburg and the managers of HiP) for support and permission to do the work. We are grateful to Peter Banks, Matt Hayward, Anthony Maddock, Gus Mills and three anonymous referees for helpful comments on this paper.

Supplementary material

442_2008_1134_MOESM1_ESM.doc (206 kb)
Supplemental table and figures (DOC 206 kb)

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Michael J. Somers
    • 1
    • 2
    Email author
  • Jan A. Graf
    • 3
  • Micaela Szykman
    • 4
    • 5
  • Rob Slotow
    • 3
  • Markus Gusset
    • 1
    • 3
  1. 1.Centre for Wildlife ManagementUniversity of PretoriaPretoriaSouth Africa
  2. 2.Department of Science and Technology–National Research Foundation (DST–NRF) Centre of Excellence for Invasion BiologyUniversity of PretoriaPretoriaSouth Africa
  3. 3.School of Biological and Conservation SciencesUniversity of KwaZulu-NatalDurbanSouth Africa
  4. 4.Conservation and Research CenterSmithsonian National Zoological ParkFront RoyalUSA
  5. 5.Department of WildlifeHumboldt State UniversityArcataUSA

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