The montane rain forests of South India’s Western Ghats are home to several endemic species of plants and animals. One of them is the Wild Durian (Cullenia exarillata). Not only is this evergreen tree found nowhere else in the world, it also happens to be a keystone species dominating the forests of the region, providing food to numerous birds and mammals. A large species with buttressed trunks, greyish white bark and evergreen foliage, it can reach heights of 30 to 40 m, towering over the canopy. It is found growing in the wet forests of the mountain chain, at an altitude of 600 to 1400 m above the sea level, in areas which receive an annual precipitation of 3500 mm. It is known as Vedupla, Malai Kongi, Aini Pla, Vedipila, Velupla in Tamil, and Vediplavu, Karayni, Vediplavu, Mullenpali, Kurunguplavu in Malayalam.
Two other species are closely associated with the forests dominated by the Wild Durian – Mesua ferrea and Palaquium ellipticum. They are crucial to the survival of the Western Ghat’s most iconic primate species, the Lion-Tailed Macaque (Macaca silenus). Scientists have discovered that the Cullenia-Mesua-Palaquuium forests are crucial Macaque habitat. The monkeys obtain an overwhelming amount of their food from the forest canopy formed by these trees. But primates are not the only creatures to benefit from the species’ largess. Bats, civets, squirrels, rats and birds also feast on its flowers.
The Wild Durian bears upto 30,000 brownish-yellow tubular flowers in dense clusters on its terminal branches from December to April (extending to May). The tree’s tubular flowers are succulent and fleshy, with abundant nectar stored in the base, making them a mouth-watering target for several denizens of the rain forest. Very often, the flowers are decimated by the animals that come to feed on the nectar. Apart from the Lion-Tailed Macaque, the Nilgiri Langur (Trachypithecus johnii), Malabar Giant Squirrel (Ratufa indica), Giant Flying Squirrel (Petaurista petaurista), Malabar Spiny Dormouse (Platacanthomys lasiurus), Nilgiri Palm Squirrel (Funambulus sublineatus), Brown Palm Civet (Paradoxurus jerdoni), Greater Short-Nosed Fruit Bat (Cynopterus sphinx) and Leschenault’s Rousette (Rousettus leschenaultii) visit the the Wild Durian.
It is interesting to note that like the Lion-Tailed Macaque, the Nilgiri Langur, Malabar Giant Squirrel, Malabar Spiny Dormouse, Nilgiri Palm Squirrel and Brown Palm Civet are all endemic to South Asia, with ranges nearly corresponding to the peninsular region. Birds, bees, butterflies, beetles and ants also frequent the Wild Durian’s flowers. But they are not as important as the mammalian pollinators. In fact, Cullenia exarillata seems to have evolved a strategy that utilizes both bats and non-flying mammals to enable pollination. It is the latter that do most of the pollinating. Bats are not plentiful in the undisturbed rain forests of the Western Ghats. This forces the tree to utilize the services of primates, rodents and civets. As Wild Durians bear flowers and fruit during a period where much of the forest is depleted of food sources, they attract a huge number of animals. This is what makes them such an important part of the Western Ghats’ forest ecosystem.
Image Attribution: The image above, sourced from Wikimedia Commons, shows a photograph of Wild Durian fruits clustered on a tree in the Anamalai Hills of Kerala and Tamil Nadu. The photograph was uploaded by TR Shankar Raman, a wildlife botanist with the Nature Conservation Foundation of South India. The fruits are a favourite food of the Lion-Tailed Macaque.
- Flowers of India
- Interactions between non-flying mammals and flowers of Cullenia exarillata Robyns (Bombacaceae), a canopy tree from the wet forests of Western Ghats, India by TS Ganesh and MS Devi
- Silent Valley National Park