Another proof of the elephants’ extreme sociability: The little pachyderms manage to recover from the loss of their mother thanks to herd life, according to a study conducted by groups living in freedom in Kenya.
It was stress hormones present in feces that allowed scientists to study the consequences of an elephant’s death in her calf, which the band is known to be strong, even after weaning.
A species threatened by poaching
The idea came from a young PhD student from Colorado State University (USA), Jenna Parker, who is passionate about African savannah elephants, a species listed as endangered on the International Union for Conservation’s Red List of Nature (IUCN), on due to poaching. and habitat destruction.
“The global impact of poaching is poorly understood on these extremely social animals,” explains this ecology researcher, lead author of the study published this week in Communications Biology.
When you observe a herd, you realize how much the family matters. The members are always side by side – the young people are rarely within ten meters of their mother. And the reunion ceremonies extended to the whole group, after separations of only a few hours, are incredible.
Jenna Parker, lead author of the study.
When poachers (or hunters) kill an individual, this cohesion is also destroyed, threatening “the well-being of the elephants, especially among the young whose mother has been killed”.
Jenna Parker and her colleagues wanted to know how orphans feel this grief on a physiological level, by studying their response to stress. More specifically, by measuring their level of glucocorticoid hormones, which the adrenal glands of vertebrates (including humans) release in the light of a stress factor. These markers are found in the blood, saliva, urine … and feces.
Together with her team, she therefore patiently followed, between 2015 and 2016, the manure from small pachyderms on the passage of herds from the Samburu and Buffalo Springs reservations (in central Kenya).
A work that made it possible to collect 496 samples of manure from 37 baby elephants, 25 of which had lost their mothers. Only young females (males are harder to spot because they are less faithful to their herd of origin), aged 2 to 20 years (around the age of the first calving).
Of the orphans – who had lost their mother between 1 and 19 years earlier – 20 had remained in the same family unit after death, five had joined an unrelated unit.
Transient stress, filled with social support
The authors found that glucocorticoid levels were similar in the long run between orphaned and non-orphaned children. A “good surprise”, remembers the researcher, who expected that the orphans would exhibit more stress in the absence of maternal care.
This does not prevent them, Jenna Parker notes, from experiencing higher stress in the short term, as has been observed in chimpanzees in the two years following the death of their mother, and even in rats, pigs India and some birds.
“But at least those effects do not last, which shows resilience,” she comments. The strong social support of the group of elephants would come to play this role as regulation called “buffer effect”.
The predominant role of “playmates”
And there’s more: Researchers found lower stress in teens who grew up in groups with multiple peers of the same age, whether they were orphans or not. The study suggests that ‘playmates’, especially siblings, are essential in elephants.
These findings could inform the management of elephant orphanages in captivity: giving orphans the same peers could help them, and then releasing groups of tied orphans together during their captivity could facilitate their transition back to nature, the study concludes.