title: The impact of competition on elephant musth strategies: A game-theoretic model.
abstract: Mature male African Savannah elephants are known to periodically enter a temporary state of heightened aggression called "musth", often linked with increased androgens, particularly testosterone. Sexually mature males are capable of entering musth at any time of year, and will often travel long distances to find estrous females. When two musth bulls or two non-musth bulls encounter one another, the agonistic interaction is usually won by the larger male. However, when a smaller musth bull encounters a larger non-musth bull, the smaller musth male can win. The relative mating success of musth males is due partly to this fighting advantage, and partly to estrous females' general preference for musth males. Though musth behavior has long been observed and documented, the evolutionary advantages of musth remain poorly understood. Here we develop a game-theoretic model of male musth behavior which assumes musth duration as a parameter, and distributions of small, medium and large musth males are predicted in both time and space. The predicted results are similar to the musth timing behavior observed in the Amboseli National Park elephant population, and further results are generated with relevance to Samburu National Park. We discuss small male musth behavior, the effects of estrous female spatial heterogeneity on musth timing, conservation applications, and the assumptions underpinning the model.
authors.affiliation: Department of Mathematics, Florida State University, 1017 Academic Way, Tallahassee, FL 32306-4510, USA. Electronic address: jmw11af@my.fsu.edu.
authors.forename: J Max
authors.initials: JM
authors.lastname: Wyse
authors.affiliation: School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough LE12 5RD, UK. Electronic address: ian.hardy@nottingham.ac.uk.
authors.forename: Ian C W
authors.initials: IC
authors.lastname: Hardy
authors.affiliation: School of Veterinary Medicine and Science, Sutton Bonington Campus, University of Nottingham, Loughborough LE12 5RD, UK. Electronic address: lisa.yon@nottingham.ac.uk.
authors.forename: Lisa
authors.initials: L
authors.lastname: Yon
authors.affiliation: Department of Mathematics, Florida State University, 1017 Academic Way, Tallahassee, FL 32306-4510, USA. Electronic address: mesterto@math.fsu.edu.
authors.forename: Mike
authors.initials: M
authors.lastname: Mesterton-Gibbons
mesh_terms: D000349:Africa; D000374:Aggression; D000728:Androgens / Q000502:physiology; D000818:Animals; D003163:Competitive Behavior / Q000502:physiology*; D004606:Elephants / Q000502:physiology*; D030762:Estrous Cycle; D005260:Female; D005716:Game Theory; D008297:Male; D008954:Models, Biological; D012726:Sexual Behavior, Animal; D013739:Testosterone / Q000502:physiology
chemical_list: D000728:Androgens; D013739:Testosterone
keywords: African Savannah elephants (Loxodonta africana); Animal contests; Evolutionarily stable strategy