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Multipack dynamics and the Allee effect in the African wild dog, Lycaon pictus

Published online by Cambridge University Press:  04 January 2001

Franck Courchamp
Affiliation:
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
Tim Clutton-Brock
Affiliation:
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
Bryan Grenfell
Affiliation:
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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Abstract

The current decline of the highly endangered African wild dog (Lycaon pictus) may be partly due to the population dynamics induced by their social system. African wild dogs are obligate co-operators, and their need for helpers could generate inverse density dependence at the pack level. We show, through a mathematical model, that this can create an Allee effect, leading to a lower population size and a higher risk of population extinction, compared to populations with direct density dependence. This is due to three different processes. All three processes can increase population extinction individually and probably occur simultaneously in African wild dogs. First, inverse density dependence causes significantly higher rates of pack extinction. Second, it also increases the probability of failure to colonize territories by founders. Third, the Allee effect at the pack level (with a critical number of individuals), generates an Allee effect at the population level (with a critical number of packs). These three processes are likely to apply to other obligate co-operative breeders. Furthermore, our results suggest that habitat fragmentation and destruction, as well as increased human pressure, increase the effects of inverse density dependence. Direct and indirect anthropogenic effects may thus be more detrimental to obligate co-operative breeders than to other species.

Type
Research Article
Copyright
© 2000 The Zoological Society of London

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