Wild Elephants in the Nilgiris help seed dispersal of fruit bearing plants: reveals new study

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Elephant herds in Silent Valley National Park in Western Ghats of Kerala
(Photo Courtesy: N P Jayan)

Wild tuskers in Southern Western Ghats are just like birds. Not that they can fly, but like their winged friends, they play a crucial role in the seed dispersal of some plant species found in this rare biodiversity hotspot, says researchers who studied the seed dispersal role of elephants here.According to their study, Asian elephants (Elephas maximus) are important seed dispersing agents of some fruit bearing plants in the semi-deciduous, thorny forests of the Nilgiri Biosphere Reserve, the oldest biosphere reserve in India which lies in the Western Ghats.

By examining the fruit seeds and remnants in elephant dung piles in the study areas, the researchers found that this biggest terrestrial animal plays a key role in the seed dispersal of at least eight different plant species found in the area like Acacia intsia (Twisted Acacia), Artocarpus heterophyllus (Jack Fruit), Bauhinia racemosa (Bidi Leaf Tree), Grewia hirsuta (Kukurbicha), Grewia tiliifolia (Dhaman), Mangifera indica (Mango), Tamarindus indica (Tamarind) and Ziziphus mauritiana (Indian jujube). Among these eight, Wild Tamarind and Twisted Acacia are the favorite fruit of the tuskers, since their presence was significantly more in the dung piles than the other six species, says the study which is published in the Journal of Threatened Taxa.

Earlier research in Asian and African forests have shown that elephants are a very effective seed dispersing agents. They devour huge amount of fruits and carry the seeds to long distances from the parent tree with their behavior of moving to wide-ranging areas. Moreover, seeds are defecated intact. It is also observed that the dung piles often provide a nutritious medium for seed germination.

Fruit Diet of the Pachyderms in the Nilgiris

The study has also revealed some interesting insights into the food habits of the wild elephants in Nilgiris. According to the researchers, elephants in the area consume more fruits during dry season when compared to the wet monsoon season. “Seeds and other fruit parts appeared in the dung piles significantly more frequently during the dry season than in the wet seasons”, says the study.

Moreover, tuskers prefer a fruity diet more in the thorny forests, than in a moist deciduous area, shows the results of the study. The study also confirms the sometimes notorious truth of the tuskers’ irresistible temptation for mango and jack fruits when they are in moist deciduous areas in NBR. Remnants of both of these fruits were frequently found in the dung piles from moist deciduous areas. Often, fruiting jack fruit trees are blamed for wild elephants raiding villages in the forest fringes of NBR.

However, pachyderms have dislikes for certain items in their fruits menu, says the study. Fruits of Z. mauritiana are less preferred by these animals, as indicated by the lower presence of these fruit remnants in the dung piles, despite the wide presence of the plant in the forests of NBR.

But don’t misunderstand that the wild elephants in Western Ghats consider fruits as their favorite item like their African and Malayan counter parts, reminds the researchers. Grass species like bamboo are the first preference for tuskers in these areas. Fruits are second or third in the list. “Elephants consume a lesser number of fruit species in the tropical dry forests of Nilgiri Biosphere Reserve than in the rainforest habitats of Asia and Africa”, points out the study.

Asian Elephant Population in the Nilgiris

The study was carried out in Mudumalai Wildlife Sanctuary which is presently a Tiger Reserve, Nilgiri North, Sathiyamangalam and Coimbatore forest divisions, Bandipur Tiger Reserve and Wayanad Wildlife Sanctuary which all come under Nilgiri Biosphere Reserve.

According to the figures of the last elephant census, the area holds the one of the largest population of Asian elephants in the world, with approximately 4,500–5,800 individuals.

During the study period, the research team extensively followed elephant herds and bulls in these areas. According to the researchers, they have collected fresh dung piles whenever defecation was observed. On a total, they have examined 455 elephant dung piles during the whole study period.

Nagarajan Baskaran and Ajay A. Desai of  Bombay Natural History Society have co-authored the study.

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