A new study shows that orphaned elephants show signs of long-term stress, but being placed with peers of the same age could reverse this effect.
Researchers measured stress levels in African bush elephants (Loxodonta africana) in Kenya by taking samples of their dung.
They found that social support from other elephants of the same age can alleviate the stress caused by the loss of their mother.
Previous research has shown that maintaining relationships with other members of the same species reduces an individual’s response to stress, a phenomenon known as “social buffering.”
The results of a new study support the hypothesis that this “social buffering” occurs in wild elephants.
Two orphans from the Artists 2 family, aged 13 and 14, are relaxing with their calves. One has a hanging left ear and the other (because he was killed in a shootout during a conflict between humans and elephants) had a hanging right ear. They were always together, so there was at least one pair of erect ears between them.
He already knows that maintaining relationships with other members of the same species reduces the individual’s response to stress, a phenomenon known as “social buffering.”
When a vertebrate encounters a stressor, the adrenal glands release more glucocorticoid hormones into the bloodstream.
Social buffering occurs when the presence of one or more companions reduces the release of such a hormone.
For example, strong bonding with other males reduced glucocorticoid release in wild male macaques (Macaca sylvanus), and the presence of a familiar companion reduced glucocorticoid release after exposure to a stressor in captive male squirrel monkeys (Saimiri sciureus).
While most studies of social buffering have been in primates and laboratory rodents, it has been observed in other taxa, including fish and birds.
The new study was conducted by experts at Colorado State University at Fort Collins and published in the journal Communication biology.
“We observed correlations that point to the importance of peers and family relationships in buffering maternal loss for orphan survivors,” the article says.
“Preserving social bonds in wildlife populations can make individuals in these populations more resilient to disturbance and optimize their physiological state.”
For the study, the team collected stress responses from 25 orphaned and 12 non-orphaned female African elephants from the Samburu and Buffalo Springs National Wildlife Refuge in Kenya.
Elephants have ranged in age from seven to 21 years old, about a third of the species’ lifespan of 60 to 70 years.
Orphaned elephants lost their mothers between one and 19 years before the study due to poaching or drought.
Poaching and severe drought between 2009 and 2014 killed many adult female samburu populations, leaving behind scattered families and orphaned cubs.
Of the 25 orphans, five left their birth family to join an unrelated group or form a group with other orphans after their mother’s death.
The remaining 20 orphans remained in the same family after the death of their mothers.
The researchers measured the concentration of glucocorticoid metabolites (GCM) in 496 elephant dung samples between 2015 and 2016.
One of the studied American orphans, aged 13, crosses the Ewaso Ngiro River with her calf and her sister’s calf.
The researchers measured the concentration of glucocorticoid metabolites (GCM) in 496 elephant dung samples between 2015 and 2016. The picture shows samples of three elephants.
HCM are formed as a result of the breakdown of glucocorticoid hormones, which are secreted by the adrenal glands in response to stress.
Thus, according to the researchers, an elephant with a higher concentration of HCM in manure will experience more stress.
The team found no difference in faecal GCM concentrations between non-orphans and orphans several years after their mother’s death.
This is despite the fact that orphan elephants have a lower survival rate than non-orphans.
However, concentrations were lower among those who lived in groups containing more elephants of the same age, regardless of whether they were orphans.
Family or members of a herd of wild African elephants (Loxodonta africana) in the Kruger National Park, South Africa (file photo)
This suggests that social support may help reduce stress levels among orphaned elephants, and support from peers of the same age may help reduce stress levels among all elephants.
Interestingly, levels of glucocorticoid metabolites were lower among orphans who left their family group after the death of their mother compared to non-orphans and those who remained in their family group.
They suggest that this may be due to suppression of adrenal glucocorticoid release in response to prolonged high levels of stress.
The scientists’ new findings could help manage captive orphan elephants.
Providing captive orphans with companions of the same age and keeping groups of bonded orphans can help reduce their stress levels.
In addition, the joint release of bonded groups of orphans from captivity may facilitate their return to the wild.
Unfortunately, the African bush elephant is currently critically endangered due to hunting and is currently listed as “Vulnerable” on the IUCN Red List.
Elephant populations in southern and eastern Africa, which once showed promising signs of recovery, are under threat due to a recent surge in poaching for the illegal ivory trade, according to WWF.
AFRICAN SAVANNA: THE LARGEST LAND MAMMALS IN THE WORLD
African bush elephants are the largest land animals on Earth. An adult male African savanna can stand 13 feet tall at the shoulder and weigh 14,000 pounds.
As they move, they push through trees to reach their branches and roots, helping to preserve grasslands, and they use their tusks and trunks to dig for water, creating pools that many other animals need to survive.
Habitat loss and poaching are the biggest challenges for their survival. As the African human footprint has increased, elephant habitats have been converted to farmland, cut down through industrial logging and mining, and otherwise developed with roads and settlements.
Elephants are killed by poachers for their ivory and meat, and farmers sometimes kill them to protect their crops, which are often raided by elephants.
The IUCN lists African bush elephant populations as vulnerable. Both males and females of the African savannas have tusks and are therefore targeted by hunters.
Three living elephant species are currently known: the African bush elephant, the African forest elephant, and the Asian elephant.
A noticeable difference between African savannahs and African forest elephants is in size – the savannah is larger and has larger and more curved tusks.
Asian elephants have much smaller ears than both African species, and usually only male Asian elephants sport tusks.