In Search of the Mugger Crocodile

Published in Reptiles, Jan 2006

In the summer of 1999, Rom Whitaker, a herpetologist from India and I went to Sri Lanka to look at mugger crocodiles (Crocodylus palustris). Our goal was to make the ultimate film on the mugger. But first, we needed to find a place with a mother load of muggers where we would set up base. Sadly, there were no big populations of crocs anywhere on the Indian subcontinent. Rom had done a croc survey in Sri Lanka in the late 1970s and remembered seeing large congregations of crocs in Yala National Park in the southeastern corner of the island nation. So that’s where we headed.

Yala is a woodsy, dry evergreen forest by the beach. The Park is dotted with pools, ponds and lakes – every one of them man-carved. Around the 9^th century, this region was a part of the Ruhunu kingdom, a mysterious civilization of whom nothing is known. These water bodies were excavated then by hydrological engineers to water the huge rice fields. No one knows what caused this kingdom to vanish with no trace. Over the centuries, the forest reclaimed the land and today this sprawling 373,000 acres of forest is known as Yala (or Ruhunu) National Park.

When Sri Lanka became a part of the British Empire, Yala National Park was a Hunting Reserve. Up until the 1950s hunting parties of Europeans and Sri Lankans came here to shoot leopards, elephants, buffalo and boar. Nobody paid much attention to reptiles. In the records of the Park there is a lone entry to do with reptiles: on 1 Nov 1948, a party of 6 had shot 3 crocs, 4 boars and 1 python. The lack of croc references is surprising considering that crocs were everywhere and an easy target for any frustrated hunter wanting to take a pot shot. Or may be they just didn’t think it was worth writing home about!

Yala National Park: The Croc Paradise:

A lot of the waterholes had dried up at the time of our visit. There were about 10 large perennial ponds we concentrated on as all the crocs could only be here. We counted an average of 100 crocs a day during the dry season. In several ponds painted storks hunted for fish with impunity while crocs cruised close by. The birds were ever watchful but there were moments when they were too engrossed in the hunt to pay any attention to the predator close by. It took only a couple of days to fish out a pond. Then the hunters left for fishier pastures. Both birds and crocs looked very well fed and it seemed obvious that the storks and crocs had forged some kind of benign relationship. The birds’ constant probing around in the mud startled some fish right into the jaws of the waiting croc but it wasn’t clear how the deal worked for the storks. May be just the privilege of being allowed to fish in the murky waters. Elephants walked past basking crocs to drink water while buffaloes wallowed in the mud under the seemingly sleepy gaze of the reptiles. Deer were more wary of the tourists than the immobile crocs.

If a croc could stake its territory in a perennial pool, he had nothing to worry about. Others however have to slog – digging deep subterranean bunkers to hang out in. A tracker pointed to a croc tunnel at the edge of a bone-dry pool. A well-worn path led into the tunnel. And what was more - there were old broken eggshells lying around. Where were the babies? How could they survive the summer? The tracker said he had seen the babies come out of the tunnel following their mother every evening as she walked about 500 feet to the nearest water – a saline lagoon. Rom doubted the story but there seemed no other possible way for the babies to survive. This also provided a clue to where the mother crocs were nesting. Rom checked the mouth of every tunnel for a nest. He found 2 nests with about 30 eggs in each which he estimated had been laid a month earlier. The first eggs to be laid would hatch smack in the middle of the dry season like those phantom babies that take a walk with their mother every evening. What would they eat? What about freshwater to drink? This wasn’t making any sense.

All 3 nests were on the banks of saline lagoons. This may be because that is where the big female crocs congregate in the nesting season. We tested water samples from a couple of lagoons for salinity. The laboratory reported that the water was more saline than seawater, with the strong admonition: “remove crocodiles immediately”! Rom thought the young ones had little chance of survival in the very salty water. They were doomed year after year; we never saw any of the previous year's young. (We never found any nests along the river banks nor did we get a chance to probe around many of the freshwater ponds.)

Although the landscape of Yala is flat, a few rocky outcrops stick up. Rainwater collects in pools in the rocks and some of them are deep enough to be perennial. There were croc scats around but if there were any crocs, they made themselves scarce. It must take a determined croc to climb up the steep rocky incline several feet above the forest. Below one such pool we spotted a bleached perfectly preserved skeleton of a 9-foot mugger croc, probably the victim of a bad summer. Close by, at the bottom of one dry pool up in the rocks, were bones of buffalo and croc – a deadly trap with its smooth slippery sides. Once you get in, you can’t get out!

We had to regularly jam on the brakes to allow star tortoises (Geochelone elegans) to cross the road – both on the highways outside the Park and the dirt roads inside the Park. Big rugged females hotly pursued by smaller males; babies no bigger than a hen’s egg! Locals told us that the tortoises were the scourge of their tomato fields and the only way to combat the slow moving “pest” was to dig a trench. Apparently the tortoises fall in and die, unable to get out.

One afternoon while we were driving through the Park a message reached us that the Army wanted Rom to come immediately to the check post. The Army is a constant presence ever since they wrested control of the Park from armed rebels who chased away or killed the Wildlife staff a decade ago. Caught in the rafters above the security guard’s bed was a beautiful cobra (Naja naja). The soldiers, toting semi-automatic weapons, stood nervously by as Rom climbed up to the rafters and with a snake hook coaxed the cobra out of its hideout. What to do next? He couldn’t climb down and he didn’t know what to do with the snake. A quandary the snake solved by diving onto the bed below. Immediately the soldiers scurried out of the room. The cobra, stunned by the fall, conveniently waited until Rom could get it into a snake bag. Later in the evening, it was released into the dry forest several miles away from the check post.

Digging burrows is just one of the two ways the crocs deal with the dry summer. A lot of the crocs hike overland, across the jungle, along pathways they have probably used for several years, to deeper ponds. With the kind permission of the Wildlife Department, we walked along the dry riverbed of the Menik Ganga (with armed guards in case of an elephant or buffalo attack!) and there were croc tracks everywhere on the sand. A major nocturnal migration was happening unseen.

Lunugumvehera National Park: Croc at the end of the tunnel:

Almost contiguous with Yala to the North is Lunugumvehera National Park. It receives far less attention from tourists and the wildlife authorities than it deserves. Seasonal farms have come up along the riverbanks, irrigated by water lifted from the river. The river that runs through the Park is dammed and thus dry in summer so the farmers had gone home. They return only when the rains came and the river began to flow again. The embankments, we discovered, were riddled with big holes -- croc tunnels! A rotting corpse of a seven-foot croc with a stick driven into its skull lay by one of the tunnels. Not a good sign for croc conservation!

Rom devised a method of using long lengths of plastic pipes to measure the depth of the croc tunnels. Put together, the pipes measured 35 feet, but the tunnels were sometimes even longer! Most of these deep tunnels would have been worked on year after year by the resident croc. Rom was also curious about the temperature inside the tunnels and chose to crawl into the largest ones to find out! The burrows were clean and dry inside and several degrees cooler than the outside. I was worried that an agitated croc would charge out, but figured Rom's nose was large enough to handle the confrontation!

As it turns out, some of the tunnels were quite short and while rounding a bend, Rom did indeed come upon the resident croc or two that were just as surprised to see him. But none of the crocs did much more than hiss.

After checking out a fair number of tunnels, Rom wondered if the crocs in tunnels are in metabolic depression (a phenomenon seen in other reptiles that aestivate) – the crocs drop their heart rate to a minimum, reduce their breathing frequency and slow down all bodily functions. By entering a form of deep sleep-like state, they are able to tide over months of inhospitable dry season with no food and no water. When encountered deep inside their tunnels, they re-gained animation enough only to hiss; but couldn’t charge. Measuring metabolic depression is tricky business. By the time you rig the croc with all the probes and electrodes needed to measure their heart beat, brain reaction time, breathing frequency, the croc wakens completely. So, while we can guess and suspect that this is what is taking place, we have yet to quantify and prove it.

One croc, however, wasn’t in metabolic depression. When Rom stuck his head inside the tunnel to see if anyone was home, she came out leaping and hissing, missing his head by inches. Rom nearly tripped trying to put a safe distance between the croc and him. We discovered a nest of eggs at the mouth of her tunnel the next day, obviously the reason why she was awake and alert.

Village crocs:

If you thought “ugly” reptilian predators could only survive in Sri Lanka’s National Parks, you’re wrong. As we were. Local friends hesitantly told us of crocs in the neighboring village canal. Rom jumped up exclaiming “Show me!” Our friend, Shantha, led the way across the rice fields. A tiny copse of coconut trees standing out among the vast plain of rice was where we were headed. As we came closer, we could the see the canal, cutting a swathe through the fields. The copse was totally tangled in thorny vines; access inside was going to be difficult. We were seeking a way in and came upon a freshly dug up croc nest. An egg predator, probably a monitor lizard (Varanus bengalensis), had found the nest and worked its way through the gooey contents; the egg shells untidily strewn all over the area. So crocs were there all right. As we came right around the corner we saw the tunnels, about 10 of them, side by side. The Irrigation Department was de-silting the canal and so it was bone dry. We could only assume that the crocs survived on the fish that came washing down with the water when the sluice gates upstream were opened. Rats that thrived on the rice could be dietary supplements. If crocs didn’t get in the way of humans, they could survive just about anywhere in seemed.

The head of a croc was resting at the mouth of one tunnel. It was in trouble. While desilting the canal, the maintenance crew had also widened it, shaving the croc’s tunnel down. It could barely pull its head in and after seeing two dead crocs inside a National Park, we feared for its life.

Discussions with the Wildlife Department followed and permission was given to translocate the croc. A week later, we arrived with the local Wildlife officials and the entire village to move the croc to its new home. Rom slipped a noose around its neck and before hauling it out, warned all the spectators to watch out – the croc could roll, snap and charge. The croc came out as meek as a tame pussycat. It was in metabolic depression! With enthusiastic Wildlife staff helping, Rom tied its jaws with elastic and loaded it onto the back of a pickup. It was released in one of the perennial lakes 45 minutes away, in Yala National Park. It was an hour and half before the croc gradually came to and could walk to the water.

Katagamuwa: The Lake of Crocs:

We were repeatedly told to visit a place called Katagamuwa. Everyone insisted that there were hundreds of crocodiles there. Finally, we shook off our cynicism and made the trip. Sure enough, Katagamuwa Lake had shrunk to that critical size. Any bigger, it would have been impossible to see the crocs; any smaller and they'd have all left for deeper waters. What we saw truly staggered us: Great big mugger crocs merrily fishing for hefty snakehead fish and catfish. It was dawn and the early morning light filtered through the trees, turning the crocs' hides yellowish gold. When the sun came up a bit stronger, these hulks hauled themselves out onto the banks like Europeans sunbathing side by side, soaking up the heat. We counted about 150 big crocs (left out the small ones) in the primeval splendour of the morning light. This was perfect.

From way before dawn, we could hear mugger hunting for fish, frogs and even an occasional stork - splash, crunch, gulp, gulp, gulp. A rosy sliver of sunlight finally tiptoed onto the scene. The bungalow was built conveniently close to the lake where I hung out. Rom, being the intrepid croc man, was ensconced behind a bush near the lake, spying on the crocs. It seemed as if the crocs were hunting systematically, in a group, much the way otters, orcas (killer whales) and dolphins do. The whole bunch of crocs would drive fish from one end of the water body to the other and then launch into them. Then the process would be repeated, across to the other shore: a synchronous smorgasbord. Rom wouldn't give them the benefit of cleverness though; he still maintains that the coordination of the hunt was coincidence. If one croc grabs a fish and creates a splash, the others will come over to investigate whether food is on offer. Then, more splashes follow that attract still more crocs and so on until the entire gang of crocs sail up and down the length of the lake in serendipitous coordination.

Crocs are as much creatures of habit as they are opportunists. By 9 o'clock the crocs were done for the morning and chose to spend a couple of hours basking, the sun revving their body engines to digest the huge meal they had had on a cool stomach. When it got too hot, they lazed in the water, playing politics. If a subordinate showed too much brashness, he had to be cut down to size; if a rival tried to usurp the top croc's place in the hierarchy he had to be trounced. The crocs had another big meal at dusk. They were so in tune with the time of day, that you could set your watch by them. Well, give or take a few minutes!

Through the day there were other creatures to watch. My inventory of animals that visited the lake to drink included: a pair of jackals with two pups, too many peacocks and peahens to count, wild buffalo, spotted deer, gray langurs, toque macaques and a ruddy mongoose – Rom collectively refers to them as “croc food”. And all the while, a pair of fishing eagles surveyed the scene from above. At night a small herd of elephants showed up for a drink causing Rom to come scurrying to the safety of the bungalow.

In all the time we were in Yala we were bound by Park restrictions. The one that we chaffed at the most was the one that demanded that we not step out of our vehicles. Those rules didn't apply to Katagamuwa Lake, as it wasn't a part of Yala at all. It formed the centerpiece of Katagamuwa Wildlife Sanctuary. Every morning we woke up to find signs of wild animals all around the bungalow. An elephant had come within 50 yards of us as we slept in a line of beds on the veranda of the bungalow, dorm-style, lulled to sleep by the buzzing of tree crickets punctuated by an occasional leopard call. We later met a scarred ranger who was dragged off a similar bungalow veranda by a leopard and lived to tell the tale.

Katagamuwa was a good summer bonanza for the crocs, but the water could not have lasted more than a fortnight. All those 150 crocs would then have to hightail it to the river about a mile away. We couldn’t wait around to see this happen and were forever haunted by visions of a long croc migration through the forest. But that will have to wait until a research project that we’re working hard to set up gets going. Until then, Lanka’s mugger crocs will have to wait!

Our survey of crocodiles in southern Sri Lanka lightened our hearts at the prospects of the mugger’s survival. There is no place on the entire Indian subcontinent that supports crocodiles in such numbers as in the tiny island nation of Sri Lanka. We think that it is the special brand of Buddhism practiced here that lends an aura of protection to all things, and the dangerous and scaly need it more than anyone else. In this short time we’ve seen more snakes and lizards walking and slithering through people’s backyards than in all the time we’ve spent in India. And these are “creepy crawlies,” mind you. Enhancing an already strong religious sanctity for all life with conservation education will go a long way to securing the mugger crocodiles’ future.