Wednesday, February 28, 2007

SIZE MATTERS!



Published in Sanctuary Asia Vol XXVI No. 6, Dec 2006

Kalia was a woman-eater. He was estimated to be a 23 to 24 foot (7.01 to 7.32 m.) salt-water crocodile who ruled a 10 mile (16.66 km.) stretch of the Dhamra River in Bhitarkanika, Orissa. The then Raja of Kanika wrote in 1973 that this unusually dark skinned reptile eluded shikaris including his grandfather and father for 50 years. In 1926, the captain of a ship on a run from Chandbali to Calcutta eventually shot it. The injured reptile crawled onto the bank taking shelter in the reeds and tall dry grass. Seizing the opportunity, the villagers set fire to the vegetation killing the croc.

For several years, Kalia’s skull welcomed visitors to the palace in Rajkanika while the bangles and anklets found in his belly were displayed on a table, gruesome reminders of a horrific period in the region’s history. J.C. Daniel and S.A. Hussain of the Bombay Natural History Society were the first to measure the salt-water crocodile’s skull in 1973 and reported that it was the largest skull in the world at 100 cm.

Robert Bustard and Romulus Whitaker wanted an accurate figure and in 1974 they went up to Bhitarkanika to measure the skull. It was hanging way up on the wall out of reach and it wasn’t a simple job getting it down. So using a stick they came up with 98 cm. Years later, Rom realized that they had made a mistake. Instead of measuring the skull from snout tip to the occiput (back of the head of the upper jaw), they had measured it all the way to the back of the lower jaw, a mistake that several people continue to make thus confusing the issue of crocodile morphology.

If you are wondering why the measurement of the skull has to be so specific, it’s because crocodile biologists use it to extrapolate croc sizes. The length of the skull (measured along the median line from the tip of the snout to the back of the occiput) is multiplied by seven to arrive at the animal’s total length. Scientists came up with this equation after measuring hundreds of alligators in the United States and rapidly biologists around the world began using it to estimate the lengths of several species of crocodiles.

Although there have been several reports of bigger crocodiles being shot in Australia – one was estimated to be 27 ft. (8.23 m.) – there is not a shred of evidence (skull, skin or photograph) to prove the hunters’ claims. In the 19th century, a monstrous 33 ft. (10.06 m.) croc was reportedly shot in Bengal and the skull lodged at the British Museum of Natural History. When the skull was measured it was only 60 cm. long and a simple arithmetic puts the animal at 13.78 ft. (4.20 m.).

For a couple of decades Rom tried unsuccessfully to access Kalia’s skull and in recent years began to fret that it might have disintegrated. Through Aurodam David in Auroville, we finally met Shivendra Bhanjdeo, the Yuvaraj of Kanika. He confirmed Rom’s worries – the skull was indeed falling apart and he wanted assistance in preserving it. Rom, in turn, sought the help of Dr. Russ McCarty, paleontologist at the Florida State Museum in Gainesville, who is a professional preserver of bones. He recommended a substance called Butvar (polyvinyl butyral). It wasn’t available in India, so friends kindly brought over a pound of the white crystals.

Earlier this year, we went up to Bhubaneshwar where the skull had since been moved from Rajkanika. It wasn’t in as bad a shape as we feared – the sutures holding the various parts of the skull were still intact. A slice of the upper jaw was missing (as it was even in the 1973 photograph); the captain must have shot the animal through the body. The skull had to be cleaned thoroughly and an enterprising businessman friend, Vinny took on the dirty work – alternately brushing and pumping jets of air with a bicycle pump, he managed to get most of the grit out. It was impossible to reach the crevices and the tooth sockets, so he hauled it off to the local tyre puncture fixer. It was only because Vinny was barking orders that the bewildered mechanics did what was needed. After being air-blasted, the skull returned looking several shades whiter. The Butvar had to be dissolved in acetone (without forming lumps, just like good gravy) and the thick glue brushed on the skull. An iron tub (plastic melts when it comes in contact with acetone) of adequate size was found and with the heavy skull levered by a long bamboo pole, the Butvar was poured over it. The preservative soaked into all the cracks, crevices and pores virtually encasing it and now the skull is good to last another 100 years and probably a lot more.

Finally, the moment Rom had been waiting for 30 years arrived. The tip of the snout to the occiput measured only 73.3 cm. We added three centimetres for the four per cent shrinkage when the skull dried out, and checked and double-checked the measurements. There is no doubt about it, by using the standard ratio for crocodile head length to total body length, Kalia would have measured 17.52 ft. (5.34 m.), significantly short of the 23-24 footer that it was claimed to be.

Some experts however, have expressed doubt if the 1:7 ratio can be applied universally. While the ratio is consistent in alligators, it varied wildly in crocodiles. In 1979, while Rom was doing a crocodile survey in Papua New Guinea, tribal hunters proudly showed him the skin of a crocodile that measured 20.34 ft. (6.2 m.). The fresh skull was 72 cm. long making it a 1:8.6 ratio. The behemoth had drowned in a tiny barramundi net.

In another instance, Australian croc biologist Grahame Webb measured a salt-water croc skull at 66.6 cm. belonging to a freshly killed 20.18 ft. (6.15 m.) animal. This ratio of 1:9.23 made Kalia a whopping 23.11 ft. (7.04 m.), closer to the Raja of Kanika’s claims. As a final test, we measured the closest giant at hand, Jaws III, at the Madras Crocodile Bank. The ratio was 1:9. The emerging theory is that young crocodiles may follow the 1:7 ratio, but as they grow older, the skull doesn’t keep up with the rest of the body, until at 35+ years of age they reach 1:9. If we could estimate these growth changes, it would be relatively simple to estimate the age of crocs.

Recently, we traced the skull of a false gharial from Borneo to the Munich Museum. It measured 81 cm. (snout tip to occiput). So the current record holder for the largest crocodilian skull in the world is not a salt-water crocodile (the traditional favourite) but an endangered long-snouted fresh-water reptile. It seems likely that none of these ratios would apply to gharials and false gharials so we can only speculate what length the Bornean false gharial reached.

Among crocodiles however, the largest skull, measuring 76 cm, belonged to a salt-water crocodile from Cambodia, now at the Paris Museum. The second largest skull (73.5 cm) is of an American crocodile at the American Museum of Natural History, New York and the Kanika skull ranks third in the world. There may yet be other larger skulls collecting dust in private collections but until they are measured, all stories of humungous crocodiles remain in the realm of old hunters’ tales.

The crocodile census conducted in Bhitarkanika in January indicated the presence of a 23 ft. (7.01 m.) crocodile (would we love to put a tape measure on that beast!!). Given the high degree of protection the Crocodile Sanctuary enjoys from the Orissa Forest Department (and the salt-water crocodiles themselves), it seems that this is one of the few places on the planet where these giant crocodiles will continue to rule into the 22nd century.

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