Behavioral and Physiological Dynamics of Musth in Asian Elephants

dc.contributor.advisorFreeman, Elizabeth W.
dc.contributor.advisorKiso, Wendy K.
dc.creatorLaDue, Chase Andrew
dc.description.abstractIn-situ and ex-situ populations of Asian elephants (Elephas maximus) are unsustainable in the long-term and require integrative approaches to address issues impacting their conservation status. Male elephants pose distinct challenges: they are more likely to engage in human–elephant conflict in the wild, and they require specialized care in zoos and other similar settings. Musth is a unique sexual state in elephants and is thought to be a major contributor to these challenges. However, our limited understanding of the nature of musth in Asian elephants limits our ability to implement animal-centered conservation strategies. The purpose of this dissertation was to characterize the behavioral and physiological variation of musth in wild and zoo-housed male Asian elephants in Sri Lanka and North America, respectively. This work was organized by four principal objectives: (1) identify intrinsic and extrinsic factors that influence behavioral activity around musth in wild and zoo-housed male elephants; (2) investigate the effects of age and musth on male social behavior in wild and zoo-housed elephants, and group formation in wild elephants; (3) utilize fecal samples collected longitudinally from zoo-housed elephants to determine factors that influence musth and three fecal hormone metabolites potentially associated with musth; and (4) integrate behavioral and hormonal datasets from wild and zoo-housed elephants to explore potential associations between behavioral and hormonal variation in males. To draw qualitative comparisons, data collection procedures were similar between in-situ and ex-situ elephant populations. In the first study, I identified characteristic behaviors that changed with the progression of musth in both wild and zoo-housed elephants, including increased activity, investigatory behavior, locomotion, and stereotypy (in zoo elephants), and decreased foraging. Behavior in zoo elephants was also influenced by factors such as age, space availability, and temperature. Based on these results, I proposed four behavioral stages of musth (non-musth, early musth, full musth, and post-musth) that can be reliably monitored with visible musth indicators [i.e., temporal gland secretions (TGS) and urine dribbling (UD)]. For the second study, I used a similar observational approach to identify factors that influence social behavior in male elephants. Results of this study showed that group formation in wild male elephants was associated with the interaction of age and musth status. Furthermore, broad categories of social behavior (aggression, prosocial behavior, dominance behavior, and submissive behavior) were correlated with changes in the social environment in wild and zoo-housed elephants, and these behaviors also were associated with age and musth status in zoo elephants. In the third study involving physiological variation of musth in zoo-housed elephants, I found strong associations of intrinsic and extrinsic factors with concentrations of fecal androgen metabolites (FAM) and fecal glucocorticoid metabolites (FGM). Additionally, the duration of musth episodes was negatively associated with body condition and positively associated with exposure to male conspecifics. TGS and UD activity also was correlated with changes in FAM and FGM concentrations. Finally, the fourth study demonstrated that many of the behavioral changes characteristic of musth also were associated with increased FAM concentrations (and increased active behavior and locomotion was positively related to FGM concentration in zoo-housed elephants), illustrating the multiple scales with which male elephants respond to changing internal and external environments. This dissertation emphasized the inherent variation associated with behavioral and physiological correlates of the heightened reproductive state of musth in Asian elephants, an endangered species with in-situ and ex-situ sustainability challenges. In identifying the intrinsic and extrinsic influences of this variation, we can develop informed approaches to conserve elephants as they respond to ever-changing internal and external environments.
dc.format.extent282 pages
dc.format.mediumdoctoral dissertations
dc.rightsCopyright 2022 Chase Andrew LaDue
dc.subjectAnimal behavior
dc.subjectConservation biology
dc.subjectZoo biology
dc.subject.keywordsWildlife conservation
dc.titleBehavioral and Physiological Dynamics of Musth in Asian Elephants
dc.typeText Science and Policy Mason University in Environmental Science and Policy


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