(Paris) One more proof of the extreme sociability of elephants: the little orphan pachyderms manage to console themselves for the loss of their mother thanks to life in a herd, according to a study carried out on groups living in freedom in Kenya.
Posted at 12:19 p.m.
It was stress hormones present in feces that allowed scientists to investigate the consequences of the death of an elephant in her calf, with which the bond is reputed to be strong, even after weaning.
The idea came from a young doctoral student from Colorado State University, Jenna Parker, who is passionate about African savannah elephants, a species classified as endangered on the red list of the International Union for Conservation of Nature (IUCN). ), due to poaching and habitat destruction.
“The global impact of poaching is poorly understood on these extremely social animals,” explains to AFP this researcher in ecology, main author of the study published this week in Communications Biology.
“When you observe a herd, you realize how much family matters. The members are always side by side – the little ones rarely within ten meters of their mother – they touch each other when they eat, rest, watch the comings and goings… And the reunion ceremonies extended to the whole group, after separations of only a few hours, are incredible”, she develops.
Also, when poachers (or hunters) kill an individual, this cohesion is shattered, threatening “the well-being of elephants, especially in the young whose mother has been killed”.
Response to stress
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 vertebrate animals (including humans) release in the face of a stress factor, for example if an individual feels their well-being is in danger for lack of a secure environment.
These markers are found in the blood, saliva, urine…. and feces. “Faecal glucocorticoids (fGCM) are a widespread and reliable way to measure stress in wild animals, as they are non-invasive,” emphasizes the researcher.
With her team, she therefore patiently tracked, between 2015 and 2016, the manure of small pachyderms on the passage of herds from the Samburu and Buffalo Springs reserves (northern Kenya).
A work that made it possible to collect 496 samples of manure from 37 baby elephants, 25 of which had lost their mothers. Young females exclusively (males are harder to spot, because they are less faithful to their herd of origin), aged 2 to 20 years (about the age of the first calving).
The orphans had lost their mother between 1 and 19 years earlier, due to poaching or drought, which were particularly high between 2009 and 2014. Twenty of them had remained in the same family unit after the death, five had joined a unit unrelated.
“Playmates”
The authors found that glucocorticoid levels were similar over the long term between orphans and non-orphans. A “good surprise”, remembers the researcher, who expected that the orphans would show more stress in the absence of maternal care.
This does not prevent them, notes Jenna Parker, 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 don’t last, which shows resilience,” she comments. The powerful social support of the group of elephants would come to play this regulatory role called “buffer effect”.
And there’s more: Researchers have found lower stress in youngsters growing up in groups with more peers of a similar age, whether they’re orphans or not. The study suggests that ‘playmates’, especially siblings, are essential in elephants.
These findings could inform the management of captive elephant orphanages: providing orphans with companions of the same age could help them, and then releasing groups of bonded orphans together during their captivity could ease their transition back to the wild, the study concludes.