Two of the study orphans, ages 13 and 14, resting with their calves. One has a floppy left ear and the other (since killed by gunfire during a conflict between humans and elephants) had a floppy right ear. They were always together, so they had at least one pair of erect ears between them. Credit: Jenna Parker.
A team of researchers from Colorado State University, the Smithsonian Conservative Biology Institute and the Save the Elephants program in Kenya reports that social support by members of elephant herds in African savanna elephants reduces the stress levels of orphaned boys. In their article published in the magazine Communication biologyThe group describes their research on stress levels in wild orphaned elephants and their ability to recover from a major loss.
In recent decades, African savanna elephants, the largest terrestrial animals in the world, have seen populations decline due to both poaching and drought — a situation that has left many elephants orphaned. Due to the long maturation process (it takes 20 years for the elephants to reach their full size), the number of orphans in general has increased. In addition, elephant calves are heavily dependent on their mothers for the first decade of their lives. In this new effort, the researchers studied the stress levels of orphans as they adapted to sudden changes in their care.
To learn more about the stress levels of orphans, the researchers followed several herds for more than a year, closely monitoring when they defecate. They collected the samples and tested them for glucocorticoid metabolite (GCM) levels — a relatively simple way to measure stress levels in mammals. As a control, the team collected and tested samples from 25 orphans and 12 calves raised by their mothers. The orphans who took part in the study were between the ages of seven and 21 and had lost their mother when they were 19. The researchers noted that five of the orphans left their families after being orphaned to join or form groups with other orphans — the rest stayed with their birth family.
At the age of 13, one of the study orphans in the American family crosses the Ewaso N’giro River with her calf and her sister’s calf. Credit: Jenna Parker.
When testing the GCM levels, the researchers were surprised to find that the overall levels for the orphans were no higher than for the control group. But there were some individual differences. For example, they found that the calves that had “made friends” with other calves their age had lower GCM values than those that had little social support. They also found that orphaned calves living in larger groups also had lower GCM levels.
The researchers suggest that good social support can help calves that lose their mothers by reducing the amount of stress they undergo.
The social life of orphaned elephants has been significantly changed by poaching
JM Parker et al, Social support correlates with glucocorticoid concentrations in orphans of wild African elephants, Communication biology (2022). DOI: 10.1038/s42003-022-03574-8
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Quote: Social Support Found to Lower Stress Levels in Wild Elephant Orphans (2022, July 15) Retrieved July 15, 2022 from https://phys.org/news/2022-07-social-stress-orphaned-wild-elephants.html
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