A conversation Pavithra Sankaran had with biologist Sreedhar Vijayakrishnan on his work on stress in elephants. Do have a listen!
Music for this podcast was composed by Akaash Mukherjee.
And here’s the interview in text, if you’d prefer to read it:
Hi I am Pavithra and welcome to this Q&A with Sreedhar Vijayakrishnan, a doctoral student from the National Institute of Advanced Studies. Sreedhar has been studying elephants in the southern Western Ghats for the last five years, and prior to that, spent many years understanding elephants in captivity.
We will be discussing stress and stress-related behaviour in wild animals with Sreedhar.
Thank you for being with us today, Sreedhar!
Hey, it feels great to be here to share field tales!
We know that humans share a great deal of genetic material with animals, but biological studies now seem to show that we may have behavioural and physiological processes that are surprisingly similar as well. For instance, I have learnt from reading about your work that animals experience stress! It is in this context that we wanted to ask you: what are the typical sources of stress for animals?
Wild animals experience various kinds of stress in their daily life. In natural conditions a deer, for instance, could feel stressed when it senses the presence of a leopard. Prey animals can detect and feel stressed by predators, even from several kilometers away. Social living animals, like monkeys and elephants can experience stress in troop or herd relationships—subordinate animals can feel stress in the presence of a dominant individual.
What we call stress is a chemical response to a dangerous or threatening situation—the body releases chemicals and hormones that help to cope—you must have heard of the fight, fright or flight response.
Contrary to wide perception, stress responses per se are not bad—they are essential for survival. Stress could also be a result of low food availability, or a parasitic attack, or even due to genetic factors.
So stress is inevitable, and in that sense, natural. But you have been studying stress in elephants as a result of interactions with humans. How is this different?
Elephants have large home ranges—and they also migrate significant distances seasonally. In a populous country like ours, this means they come into contact with humans a lot. In the southern Western Ghats where I work, there are large tracts of forests and thousands acres of plantations of tea and coffee, dams, highways, and villages and towns, all packed together. While people in these landscapes have a remarkable history of peaceful coexistence with elephants, things have been getting a bit too close for comfort in some places. In these situations, people may drive elephants away from villages or settlements using firecrackers or with loud noises. These can be stressful situations for elephants and each herd and each individual within a herd will respond differently. We categorise stress-inducing circumstances like these as “negative interactions”. There are also benign or “neutral” interactions—for instance in a tea estate you may see workers plucking tea and elephants grazing peacefully some distance away—and neither humans nor elephants are disturbed by each other’s presence.
And you use these behaviours by elephants to deduce when they are stressed and why?
Well, yes but not only that. In a typical day in my field study area, I follow herds of elephants from dawn to dusk, observing what the specific individual elephants I am interested in are doing through the day. If there are negative interactions with humans, I know how that specific individual behaved in that situation. If the animal interacts with other elephants, I am able to observe its behaviour in those situations as well. Elephants also poop a lot. Which means I am able to follow and collect dung from the individuals I have been observing. And this dung will contain elevated stress hormones if the animal has experienced stress in the last 36 to 48 hours, and I can cross correlate this with my behavioural observations.
It is interesting how much biologists rely on animal droppings to find out what is going on their lives! What exactly do you do with the elephant poop you collect?
You’re absolutely right, Pavithra. An animal’s dropping can tell us virtually everything about its life. In my study, I am interested in understanding how stress hormone concentrations vary in the dung of elephants, following interactions with humans, social interactions with other elephants, and under varying conditions of food availability, and so on.
The dung samples we collect are preserved to avoid any contamination, and are later taken to the laboratory for analyses. In the laboratory, we follow a technique called ELISA, Enzyme Linked Immuno Sorbent Assay, a technique used even in humans for tests like HIV detection.
Are you serious? The same test for AIDS in humans and stress in elephants?!
Yes. The ELISA tests are used widely for a range of applications—all the way from HIV in humans to stress in elephants and other wildlife.
And did you find a relationship between your behavioural observations and the stress hormones in the dung samples?
So when we tested dung samples for stress hormones in elephants and tried to check if there was a corresponding stressful situation in our behavioural observations, we were in for some surprises.
Let me tell you about an elephant named Monica. She’s this really calm individual, solitary (unlike other female Asian elephants that I study), and hangs out mostly near settlements, along backyards of houses. She hardly displays any aggressive behaviour, but her stress hormones tell a different story. She consistently has high levels of stress hormones in her dung.
This could very well be a case of behavioural suppression, as seen in humans—Monica is stressed but she remains outwardly calm, like some humans who internalise their tensions. There were also individual elephants who displayed aggressive behaviour in stressful situations but their stress hormone levels remained relatively low—reminding me of people who let off steam and don’t internalise their stress! This emphasises on the importance of individual idiosyncrasies and personalities in elephants.
That’s fascinating and it brings us back to where we started: humans and animals are not only similar in that fact that we experience stress, but also in how we respond to it! Thank you for joining us and telling us about your work, Sreedhar.
Just to underline the fact that elephants are a lot like humans, I should tell you that a recent study even found that elephants can recognise themselves in the mirror!