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Orphan elephants less socially clued-up decades later, research reveals
University of Sussex psychologists studying groups of wild African elephants have shown for the first time how human activities such as culling and relocation have a long-term negative impact on deep-rooted communication skills and social understanding in survivors, paralleling what we know about post-traumatic stress in humans.
The findings, that have wider implications for species conservation as habitat loss and poaching continue to exert further pressure, are published in the journal Frontiers in Zoology.1
Disrupted elephant populations are typically impaired socially in two ways: by the initial trauma (which may involve surviving youngsters observing the killing of individuals around them) and by the subsequent loss of opportunities for interacting with older role models or experienced elders within a group.
Social learning is very important to elephants, which live in highly complex social groups where older, experienced herd members pass on successful patterns of behaviour to younger individuals within the family.
The Sussex researchers studied the effects of such disruption on cognitive abilities crucial to functioning in complex social networks. By using cutting-edge experiments to reveal complex cognitive abilities that are usually inaccessible in wild populations, they were able to generate important insights that not only have scientific importance but are also relevant to the welfare and conservation of long-lived social animals.
Professor Karen McComb and Dr Graeme Shannon conducted a series of innovative experiments where elephant vocalisations were played to target families in each population in order to simulate different levels of social threat. This allowed them to test the social knowledge of elephant survivors of culling operations and compare their responses with those of a natural undisturbed population of elephants unaffected by culling.
The research was carried out on a population of elephants in Pilanesberg National Park South Africa, originally introduced as orphans during the early 1980s and 1990s following management culls of adult and older juvenile animals in the Kruger National Park. Their reactions were compared with those of a relatively undisturbed population of elephants in Amboseli National Park, Kenya, who were exposed to the same playback stimuli.
Elephants in both groups were exposed to a set of familiar and unfamiliar calls (including playing Amboseli calls to Pilanesberg elephants and vice versa) as well as to 50 different recorded sounds that simulated calls from elephants of different sizes and ages (older and larger animals being more socially dominant).
Four key behaviours (occurrence of defensive bunching, intensity of the bunching response, prolonged listening and investigative smelling) were used to measure the responses of the elephant groups during the playback experiments. The reactions of all individuals within the family were recorded on video and systematically coded after the playback for analysis.
The Amboseli elephants not only made better decisions in correctly recognising the threat from alien elephants, they also discriminated between callers simulating different age classes and were most defensive and attentive to the oldest callers representing more socially dominant individuals.
Responding appropriately to more dominant individuals within the social hierarchy, and thus avoiding escalated interactions, is fundamental to success within complex societies where individuals may come into contact with hundreds of others in the population as they roam and feed.
There were no such differences in discrimination abilities evident in the Pilanesberg population.
Dr Shannon says: “The dramatic increase in human disturbance is not just a numbers game but can have profound impacts on the viability and functioning of disrupted populations at a deeper level.”
Professor McComb adds: “We previously knew very little of how crucial skills of communication and cognitive abilities that are at the basis of complex societies might be affected by disruption. While elephants in the wild can appear to recover, apparently forming quite stable groups, our study was able to reveal that important decision-making abilities that are likely to impact on key aspects of the elephant’s social behaviour may be seriously impaired in the long run.”
Dr Shannon concludes: “Our results have implications for the management of elephants in the wild and captivity, in view of the aberrant behaviour that has been demonstrated by traumatised individuals. The findings also have important implications for other long-lived, social and cognitively advanced species, such as primates, whales and dolphins.”
Notes for Editors
1 ‘Effects of social disruption in elephants persist decades after culling’, Shannon, G, McComb, K., et al, is published online in the open access journal Frontiers in Zoology (2013).
The paper is also featured in a Frontiers in Zoology blog spot.
McComb & Shannon lead an international team that included experienced researchers from five different institutions. The project was funded by The Leverhulme Trust and The Amarula Elephant Research Programme.
Professor Karen McComb and Dr Graeme Shannon are members of the Vocal Mammal Communication and Cognition Research group in the School of Psychology at the University of Sussex.
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