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Social Behavior and Group Formation in Male Asian Elephants (Elephas maximus): The Effects of Age and Musth in Wild and Zoo-Housed Animals - PubMed

  • ️Sat Jan 01 2022

Social Behavior and Group Formation in Male Asian Elephants (Elephas maximus): The Effects of Age and Musth in Wild and Zoo-Housed Animals

Chase A LaDue et al. Animals (Basel). 2022.

Abstract

Asian elephants are endangered, and the long-term viability of the species depends on integrative approaches to address the sustainability of in-situ and ex-situ populations. Growing evidence shows that male elephants exhibit extensive and flexible social behavior that rivals the complexity of that of females. Male elephant sociality is expected to change dramatically around the unique sexual state of musth. However, data related to male Asian elephant sociality is lacking. Here, we conducted complementary observations in Wasgamuwa National Park, Sri Lanka, and North American zoos of male Asian elephant social behavior. Age and musth status, along with other factors, were associated with variation in social behavior and group formation of males. In wild male elephants, both musth status and age impacted elephant associations within all-male and mixed-sex groups: non-musth elephants were generally sighted less often in mixed-sex groups as they aged, while the inverse occurred with musth elephants. Musth status interacted with age to predict the number of conspecifics with which a wild male elephant associated: younger males were observed with more females during non-musth (but the opposite was true during musth), and male elephants between 20 and 30 years were observed with the highest number of male conspecifics except during musth. Finally, we found variation in aggression, prosocial behavior, and submissive behavior was influenced by intrinsic (age and musth status) and extrinsic factors (group size and type) in similar ways in both populations; prosocial behavior was most common and was influenced by the number of conspecifics present (both populations), and age, group type, and musth status (zoo population), while aggression was rare, especially among older elephants. We suggest that longitudinal studies of this threatened species will be particularly helpful to promote the reproduction and conservation of Asian elephants in in-situ and ex-situ environments.

Keywords: Asian elephant; Sri Lanka; age; all-male groups; conspecifics; intrasexual competition; mate choice; mixed-sex groups; musth; sexual selection.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1

Relative frequencies of group-type sightings (solitary, all-male group, mixed-sex group) as a function of the age class and binary musth status (top panel, non-musth; bottom panel, musth) of the focal male elephants in Wasgamuwa National Park, Sri Lanka. The sample size (number of sightings) for each category is given on the horizontal axes.

Figure 2
Figure 2

Boxplots of the association of age and binary musth status of male Asian elephants in Wasgamuwa National Park, Sri Lanka, with the number of (a) adult females and (b) adult males in a male’s group. For simplicity, ages and age classes are condensed into younger (10 to 30 years) and older (>30 years) age categories in this plot. Boxes extend from the first to the third quartile, with the median indicated by a thick line; fences extend to 1.5 times the interquartile range, and closed circles indicate values outside this range.

Figure 3
Figure 3

Relative frequencies of social behavior (aggression, prosocial behavior, dominance behavior, and submissive behavior) between wild and zoo-housed male Asian elephants, separated by social group-type (all-male or mixed sex) and age of focal animal (younger = 10–30 years old, older = 30+ years old). For simplicity, ages and age classes are condensed into younger and older age categories in this plot.

Figure 4
Figure 4

Boxplot showing the association between age and rates of aggression for wild and zoo-housed male Asian elephants in all-male and mixed-sex groups. For simplicity, ages and age classes are condensed into younger (10 to 30 years) and older (>30 years) age categories in this plot. Boxes extend from the first to the third quartile, with the median indicated by a thick line; fences extend to 1.5 times the interquartile range, and closed circles indicate values outside this range.

Figure 5
Figure 5

Relationship between rates of prosocial behavior and the number of conspecifics present for wild and zoo-housed male Asian elephants. Closed circles represent individual observation sessions, with regression lines shown for each age class (darker shades represent older age classes). The absence of a regression line for an age class indicates a lack of adequate data for the construction of a relationship. Note difference in scale on horizontal ax is for wild and zoo-housed elephants.

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