Learnings from 1933, when 14 elephants died after consuming kodo millet in a Tamil Nadu forest

The recent death of 10 elephants in Bandhavgarh National Park, Madhya Pradesh has sparked widespread concerns over the conservation of the species.

When the authors read media reports stating that the post mortem reports indicated the elephants had consumed large quantities of kodo millet (Paspalum scrobiculatum), their minds didn't immediately go to foul play. They thought the elephants due of natural poisoning through toxins released by fungus-infested crops, rather than intentional poisoning by farmers through pesticides or other chemicals sprayed on the crop.

During the early 1980s, one of the authors (R Sukumar) was carrying out research on elephant ecology and crop raiding in southern India. While searching through the rather sparse literature on crop depredation by elephants, an incidence came to light in which 14 elephants had died within or in fields adjoining the Vannathiparai Reserve Forest of Tamil Nadu, close to the Kerala border, along the road from Theni to Kumili.

The incident happened on December 17, 1933, after the elephants had consumed precisely the same plant, namely, kodo millet known locally as varagu.

The well-known naturalist and coffee planter, RC Morris, had documented this incident in a short note in the Journal of the Bombay Natural History Society published in 1934. The origin and nature of the toxin was possibly unknown at that time as it was referred to be merely a poisonous narcotic in kiriku varagu (literally ‘mad millet’), presumably because it also caused symptoms such as delirium in people.

Since then, fungal infection of cereal crops resulting in production of toxins has been well documented in the literature globally. Some fungal species infect the seed of cereal crops while they are growing in the field and also during the storage of the grains. These fungi produce chemicals termed mycotoxins (myco = fungal, toxin = poison) which remain in the grains.

Consuming mycotoxin contaminated seeds could lead to various health issues such as kidney damage, respiratory problems, convulsions, cancer and interfere with foetal development in animals and humans. When ingested in large quantities, they can also cause sudden death.

Several mycotoxins are known, including aflatoxins, ochratoxin, patulin, trichothecene, fumonisins, zearalenone, ergot alkaloids, citrinin and cyclopiazonic acid. They are not always destroyed by cooking since they can withstand high temperatures. 

Many species of fungi (Aspergillus, Penicillium, Fusarium and Claviceps) produce these mycotoxins when they infect crops like maize, wheat, rice, sorghum, peanuts and oil crops during crop growth in the field and in the grain during their storage.

Mycotoxins cannot be easily detected by conventional methods because their chemistry can be altered by the plants during growth. They are seemingly tasteless and odourless and so, people consuming infected grains may be unaware of their presence. In some cases, people experiencing symptoms of poisoning have apparently resorted to traditional methods of detoxification such as drinking tamarind water or buttermilk (as stated in RC Morris’ published note).

Plant infections caused by fungi are widespread in India, mainly due to improper harvesting practices, storage as well as high temperature and moisture. A key factor may be the favourable weather condition for fungal infection through, for instance, unseasonal rains when the crop is maturing or has been just harvested.

Outbreaks of mycotoxicosis in animals have occurred in the past in regions from Kashmir, through Maharashtra to the southern states. Apart from affecting domestic animals such as cattle and pigs, mycotoxicosis is also known to affect wild animals including fallow deer, rhinoceros and even birds such as cranes in other parts of the world.

A question that has arisen in the case of the death of these elephants is how a sentient creature with a very diverse diet of plant species, including many agricultural crops, has been unable to avoid fungal-infected crops. Elephants have an exceptional sense of smell and can presumably also taste and avoid plants with toxins. A possible explanation is that mycotoxins are virtually odourless and tasteless, and thus cannot be detected by elephants.

A second explanation is that a crop-raiding elephant is eager to eat as much of the agricultural crop as possible within a short time before being detected and chased away by the farmer. In fact, an elephant can consume twice as much from cultivated field as they can from their natural habitat per hour of feeding.

It is significant that the post mortem reports indicated large quantities of kodo millet had been consumed by the dead elephants. This would have meant that sufficient doses of mycotoxins had been absorbed to cause death in the elephants.

This incidence throws up broader management issues related to dispersing and migrating elephants. The elephants in Bandavgarh had migrated from Odisha or Jharkhand through Chhattisgarh in recent times. This is part of a larger dispersal of elephants from their “native states” in central India which began during the late 1980s and continues until the present with most of the animals remaining itinerant.

The 40-odd elephants that came to Bandavgarh seemed to be the only population attempting to settle down and offering hopes for longer term persistence. The loss of 25 per cent of the population is a significant blow.

The death of elephants from fungal poisoning through consumption of infected agricultural crop is a rare event. It is possible that several such incidences have not been detected because the animal was a solitary male elephant, which is much more prone to raid agricultural fields, unlike the “mass death” of an entire elephant herd.

Unseasonal weather events, which can be expected to become more common in the era of climate change, may increase the chances of such occurrences. The process of dispersal of elephants from their original range and establishment of new populations will be a painful one, not only for farmers whose crops and lives are at stake but also heightened risks to the elephants themselves as they inhabit and feed extensively in human-dominated landscapes.

R Sukumar, National Science Chair, Centre for Ecological Sciences, Indian Institute of Science, Bangalore. TS Suryanarayanan, director, Vivekananda Institute of Tropical Mycology, Ramakrishna Mission Vidyapeeth, Chennai.

Views expressed are the authors’ own and don’t necessarily reflect those of Down To Earth.