African elephants share a so-called “herd odour" that helps them recognise members of their herd based on smell. This has more to do with the bacteria they share when going about their ritualised greeting ceremonies than the fact that they might be related. The African giants also have the uncanny ability to track humans. These are some of the findings from research conducted by Stellenbosch University (SU) elephant expert Dr Katharina von Dürckheim, as part of the PhD in Conservation Ecology that she received from SU in December 2021 on African elephants' sense of smell.
Von Dürckheim leads the new Wildlife Free to Roam (WFR) research programme in the SU Department of Conservation Ecology and Entomology in the SU Faculty of AgriSciences. The novel research programme is helping to identify and secure wildlife connectivity corridors between protected areas in Southern Africa.
Elephants' sense of smell
“Elephants leave urine and dung behind on these pathways. These are like communication hubs. They contain olfactory messages that allow them to monitor which other elephants are around and are possibly ready to mate," says von Dürckheim, who counts former Executive Director of WFF-SA and the Peace Parks Foundation Dr John Hanks among her mentors.
“When there's a spot of urine on the ground, an elephant first blows onto the sandy spot to create a sort of dust storm of particles. It will inhale deeply through the trunk, sometimes transferring particles to the Jacobsons' organ through the roof of the mouth, in what we call a flehmen response."
It was the highly ritualised way that African elephants greet each other – something she had often had the privilege of observing during elephant interactions at waterholes in various national parks – that attracted her to her PhD topic.
“African elephants have this fascinating, ritualized greeting ceremony when they get together. No matter how often we'd work with the tame elephants, they'd still always do it too. They'd urinate, defecate, secrete from their temporal glands near their eyes, rumble, trumpet, spin their bodies around and fan their ears to waft something that I call 'pachyderm perfume' around."
Such behaviour, common to pachyderms such as elephants, rhino and hippo, is something that reminds Von Dürckheim of how butterflies and moths fan their wings to spread pheromones.
Von Dürckheim started asking herself: “What message is contained in these chemical messages that elephants secrete every single time? There must be some function here."
Given her subject matter, her PhD was truly a mammoth task. Over the course of many years of study she was able to do some ground-breaking research. Hers was the first study to deep dive into the chemistry behind secretions from the genitals and buccal and temporal glands of free-ranging African elephant females. The latter causes the typical “teary eyes" of an African elephant female – something that is seldom seen in Asian elephant females.
Her research shows that African elephants can discriminate between unfamiliar and familiar members of their species from both urine and dung. They can also identify between individual elephants based on what they pick up on from the “smell" released from temporal gland, buccal and genital secretions.
Genetics not the key
In this, genetics – or whether an animal is related to another or not – does not seem to play a role. This was shown through her work on the so-called odour-gene covariance, or OGC. This topic has been explored in many other animals but Von Dürckheim was the first to tackle in elephants.
“To study OGC, you examine blood and DNA, and you analyse the body chemistry of related and unrelated animals. You see whether because of genetic closeness, related animals have a more similar chemical profile to each other than to unrelated animals."
While related elephants did share many chemical compounds, she found that these varied in intensity and identity.
Her research revealed the existence of individual identity odour profiles in African elephants, as well as a signature for age encoded in temporal gland and buccal secretions. Olfactory signatures for genetic relatedness were found only in the labial secretions of adult sisters.
Von Dürckheim was specifically interested in whether there is something like a tell-tale “herd odour" or “group odour", given the social life of elephants, and their ability to recognise relatives. She could not find a link between herd odour and group genetic relatedness. However, an odour for “herd membership" and being part of a specific grouping seems to exist.
As is the case in the social hyaena and meerkats, this elephant group odour appears to be the result of bacteria.
“Bacteria can be shared through the frequent physical and affiliative behaviour of elephants. Members of the same group often rub their bodies against each other and explore each other's bodies with their trunks, for instance.
“This is possibly what actually creates a particular herd scent – not whether the animals are related or not. However, this does not mean that elephants cannot recognise relatives, or that a genetic signature for relatedness does not exist. Much research hints at urine containing a genetic marker. This is yet to be researched in elephants."
How elephants ID humans
Working with elephants in captivity, von Dürckheim learnt more about how they use their sense of smell when humans are about.
“Elephants are highly adept at scent discriminating between humans, and scent tracking a target human across terrains.
“We put a person in the field, and an hour later we let the elephants track the person. They were successful 100% of the time!
“The results were quite revealing. Based on scent discrimination elephants can differentiate between three generations of the same human family, and between at least nine different people. They learn superbly quickly."
The formal title of her PhD thesis was “Olfaction and scent discrimination in African elephants (Loxodonta africana)".
What the official title does not reveal is that her studies had among others given this mother of two and MBA graduate the opportunity to be on the ground during a major translocation effort of 120 elephants in Malawi. She also worked alongside experts from the American Army who were interested in the ability of wild animals to detect landmines, and investigated the tracking ability of elephants given their terrific sense of smell.
Von Dürckheim says that being in the bush is her “true north". She has pursued this passion as an elephant researcher, wildlife editor and in working for NGOs. During her masters' degree years, she researched ways to solve the conflict between people and elephants in Namibia's Caprivi Strip.
Some of her previous research suggests that elephants can serve as “umbrella species" or great ambassadors for ecological networks and the “corridor cause" that she is now pursuing. Many other wildlife, including ungulates and predators such as lions and wild dogs, use their pathways too.
About the WFR research programme, she says: “The creation and conservation of wildlife connectivity corridors between protected areas in Southern Africa will allow wildlife to roam more easily between protected areas, so reducing habitat fragmentation and isolation. It further allows particularly wide-ranging wildlife such as elephant and predators, the ability to track fluctuating environmental conditions. This is important for wildlife persistence and biodiversity resilience in view of climate change and drought.
· This article written by: Engela Duvenage, on behalf of the Faculty of AgriSciences, Stellenbosch University