Zoology: Social support may lower long-term stress levels in orphaned African elephants

Long-term stress hormone levels are similar between non-orphaned African elephants and orphaned elephants living in family groups, according to a study published in Communications Biology. The findings suggest that social support may be able to mitigate the stress caused by the loss of the mother in wild elephant herds.

Jenna Parker and colleagues studied the stress responses of 25 orphaned and 12 non-orphaned female African elephants from the Samburu and Buffalo Springs National Reserves in Kenya. Elephants ranged in age from seven to 21 years and orphaned elephants had lost their mothers between one and 19 years prior to the study due to poaching or drought. 20 orphans had remained within the same family unit after the death of their mothers, while five had joined either an unrelated unit or had formed a group with other orphans. The authors measured the concentrations of glucocorticoid metabolites in 496 samples of the elephants’ dung between 2015 and 2016. Glucocorticoid metabolites are produced by the breakdown of glucocorticoid hormones, which are released by the adrenal glands in response to stress.

The authors found that the levels of glucocorticoid metabolites were similar between orphaned and non-orphaned elephants. However levels were lower among those living in groups containing more elephants of a similar age, regardless of whether they were orphaned. This suggests that social support may help lower stress levels among orphaned elephants and that support from similar age companions may help lower stress levels among all elephants. The authors also found that the levels of glucocorticoid metabolites were lower among orphans who had left their family group after the death of their mother, compared to non-orphans and those who remained in their family group. They speculate that this could be due to glucocorticoid release by the adrenal glands being supressed in response to prolonged high stress levels.

The findings highlight the importance of familial relationships and similar-age companions to the fitness and resilience of wild elephants. The authors suggest that their findings could help inform the management of orphaned elephants brought into captivity as providing captive orphans with similar-age companions and maintaining groups of bonded orphans could help reduce their stress levels. Additionally, releasing bonded groups of orphans from captivity together could help ease their transition back into the wild, they add.