The shapers of jungles

Kanha is one of the most beautiful national parks. The first thing you notice are the enormous sal trees (Shorea robusta) forming patches with closed canopies. Then you notice that they are actually stands of trees in a larger grassland. The stands are carpeted with fallen leaves. The sunny grasslands are full of herds of chital (Axis axis, spotted deer). At the edges between the open grasslands and the forest are the more cautious sambar (Rusa unicolor) and barasingha (Rucervus duvaucelii, swamp deer). But if you look closer you see the species that shapes the landscape by removing litter and tilling the ground: termites. Some are visible by their mounds dotted throughout the forest, others hide in living trees and dead logs.

I spent quite a bit of time trying to figure out how high the termite mounds were. It sounds silly, but then I was in a jeep which spent three days rushing through the forest in search of tigers. Most tourists holiday in nearby resorts, and spend their times in swimming pools and air-conditioned rooms, making a couple of forays into the jungle. Of those who come to the forest, most are interested in tigers. So tigers are a boon to the locals who make their living on tourism, and their behaviour is geared to such people. A very few visitors come to the forest to see more, and the guides and jeep drivers are happy to talk to them about their own experiences. But you just cannot get off jeeps to make measurements. So I had to improvise by taking photos of termite mounds with different things to give a scale. Everything simplified when I saw two people, forest workers, walking between two mounds. That photo clearly told me that the large mounds were about two meters high. I saw the Northern plains gray langur (Semnopithecus entellus, hanuman) crouched behind a smaller mound. These langurs are about a meter tall. So that sort of verifies my estimate by eye that the larger mounds are twice as tall.

I’ve found termites (order Blattodea, infraorder Isoptera) fascinating for a while. They are cockroaches (order Blattodea) which adapted to eating wood by harbouring a microbiome of bacteria, protists, and fungi in their stomach. In fact, the study of termites gave the first clue that many animals could have flourishing ecosystems inside them, a discovery that is now increasingly used in treating human disorders like Type II diabetes. In a forest they munch up fallen logs and leaves and are important recyclers. But they bore into trees and wood, which makes them pests for us at home or in farms. This bunch of cockroaches also developed eusocial behaviour some time in the Triassic or Jurassic, becoming differentiated into castes of workers, queens, and kings. When I was young I would see yearly swarming of termites, as a queen and her retinue set off from their old palace in search of a new home. So I know that a termite is only a couple of millimeters in size. The mound is a thousand times larger. Calling it a palace is shortchanging the mound, because I know of no human queen who lives in a two-kilometer tall palace. Perhaps one should compare it to a medieval citadel, a city which houses the court and also all the industry which supports it.

I’d spent some time photographing termite mounds up close in the Bijrani range of Corbett NP. You can see from these photos that they have a contoured surface which is rather smooth. The material glitters in the sun, which makes me think that bits of minerals in the soil, or insect chitin could be incorporated into it. I found an interesting group of papers which studied the strength and engineering of these mounds in a non-destructive way. They found that two castes of termite workers continually build pellets of wet mud. Other castes of workers then cement these “bricks” into walls using liquids that they secrete from the body. The wetness of the mud allows the suspended granules of mud to settle into any cracks in the walls that need repair, and the termite-spit then makes it proof against the hard monsoon of this part of India. Another paper led me to believe that the two meter tall termite citadels could be several hundred years old.

But which termite made these mounds? I’m as sure as I can be, without a photo of a termite, that they are made by Odontotermes obesus. I wish this common forest termite in had an easier name. This is the species which builds these tall conical mounds with flutes which look like Gaudi could have dreamt them up. But I’d seen and photographed other shapes too. Not knowing enough about termites, I’d assumed that they were merely citadels in the early stages of construction. But apparently not. Very often, the shape of a mound tells you with certainty which species built it. But Chhotani, in his 45 year old gem of a paper on the termites of Kanha NP tells us of multiple species which can be found in the mounds and fungus gardens of O. obesus. And more interestingly, he describes four different shapes of mounds, all of which seem to be built by O. obesus. With this observation he speculates that when there are more detailed studies one would find that what we call a single species now will be resolved into multiple species, each one building a mound of a given shape. Unfortunately, the study of termites in India is in its infancy. Even a paper from five years ago, which claims that there are 286 species of termites in India, making up 10% of the world’s termite biodiversity, added six new species. I was not surprised that no one has performed a gene profile of O. obesus from Kanha to check Chhotani’s conjecture. So we don’t yet know whether we can really tell the species of a termite from the shape of its mound. There are so many angles to termite life, so many loose ends in their story, that one really has to look at several pictures to piece them into one view of these shapers of jungle landscapes.

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