African elephant societies fail to fully recover from past traumatic events

ResearchBlogging.org Basic social skills of African elephants remain impaired decades after surviving devastating experiences. 

African elephants (Loxodonta africana), like cetaceans and some primates, are highly social animals that cultivate complex relationships with other members of their group throughout their long lifespans. However, extremely distressing events such as poaching for ivory, displacement to new areas and habitat destruction can lead to serious disruption of these intricate social bonds.

Older elephants are key leaders and co-ordinate activity for the entire group. They essentially act as role models for the younger members to whom they pass on vital social and environmental knowledge. However, it is these older animals that are usually targeted in poaching and culling operations, leaving the survivors traumatised after witnessing the massacre of their relatives around them.

Orphaned elephants often exhibit abnormal hyper-aggressive behaviour throughout their lives. In one case from South Africa, this resulted in the killing of 107 rhinoceroses over a 10 year period. However, a new study in Frontiers in Zoology indicates that these tragedies may also have more subtle long-term effects on social interactions with other elephants.

Researchers played recordings of female vocal calls to groups of elephants in order to assess their ability to make decisions about potential threats. The study group was located in Pilanesberg National Park, South Africa, which was founded from young elephants orphaned by the management culls of older animals in the 1980s and 1990s. Three distinct calls were used: familiar, unfamiliar and alien (a call from outside the local elephant population). The responses of the elephants were then carefully monitored.

The elephants in the study were unable to accurately discriminate between the callers, and frequently bunched into defensive formation even when presented with a familiar vocal call. More worryingly, they also failed to focus their defensive bunching on the most socially threatening individuals.

In contrast, in groups that had not experienced a traumatic event, the elephants remained relatively relaxed when played calls from individuals familiar to them. They only became defensive when they heard unfamiliar calls representing high levels of social threat.

Elephants in the wild were previously thought to be relatively resilient to social disruption as they usually succeeded in forming new family groups. However, these findings suggest that the abilities of elephants to process even basic social information may be impaired in the long-term, potentially leading to detrimental effects on the health and functioning of the entire population. Therefore, rather than simply assessing the recovery on the basis of numbers alone, future conservation efforts should focus on preserving functioning family groups wherever possible.

Reference: Shannon G, Slotow R, Durant SM, Sayialel KN, Poole J, Moss C, & McComb K (2013). Effects of social disruption in elephants persist decades after culling. Frontiers in Zoology, 10 PMID: 24152378

Video: Royal Society

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