Group Dynamics of Young Asian Elephant Bulls (Elephas maximus Linnaeus, 1758) in Heidelberg Zoo – Integration of a Newcomer in an Established Herd.
Der Zoologische Garten (N.F.) 82 (5-6): 267-292. ISSN 0044-5169.
The social organisation of elephants is based on female philopatry and male natal dispersal. The separation of males from their family group is a behavioural strategy of inbreeding avoidance. In the course of this gradual process young bulls increasingly have contact to males belonging to other herds, mainly same-aged, in form of sparring () with spending more and more time away from their own family (). After leaving the natal herd they join other males and form loose all-male groups (). This natural process during the development of male elephants, however, raises a problem for the elephant keeping in zoological gardens because of the increasing intolerance by the herd in combination with the lack of adequate keeping facilities for bulls. As the keeping of young bulls without or limited contact to conspecifics is an unnatural way of handling them, as described above, efforts are made for establishing an appropriate husbandry. Zoo Heidelberg is the first German facility, which keeps a group of young elephant bulls. Moreover it is the first zoo which undertakes the experiment to integrate another young bull in an established group.
The aim of this study was to assess the group dynamics, particularly the individual personalities and social bonds, in a group of young bulls in captivity during the integration of a new bull.
By means of the focal animal sampling () the social behaviour of the four young bulls during the first four months of integration of the new bull was continuously recorded. It was quantified by the frequencies of defined social events and the individual duration of social isolation and association with another elephant. The durations and the frequencies were standardised as the percentage of the individual observation period and the number of occurrences per hour, respectively, in order to allow the comparison of the individuals.
The four young bulls showed distinct personalities, which affected the strength and kind of social bonds between them. In general the members of the initial group interacted more frequently among themselves than they did with the new one. Particularly the initial three elephants exhibited physical contact and friendly behaviours to a greater extent than the new bull did. But the frequency and the motivation of the associations depended on the social partner both in the case of the initial group members and the new one. Furthermore the behaviour of the new elephant indicated social isolation and an elevated stress level. Beside a high frequency of social interactions, the existence of a dominance hierarchy and the progressive integration of the new bull suggest a stable social structure and therefore support the concept of keeping young bulls in same-sex groups.