Crocodiles play key role in aquatic eco systems :

Co-existence of humans and mugger crocs

By Dhaneshi YATAWARA

It is said that the word mugger is a corruption of the Urdu word ‘magar’ which means the water monster.

The Urdu word is believed to be derived from the Sanskrit word ‘makara’. Famously known as the mugger - the marsh crocodile - may look like a monster with his swift, stealthy predator skills.

The largest living reptile in Sri Lanka, crocodiles plays a key role in the aquatic eco systems.

Sri Lanka has only two species of crocodiles - one is mugger or the marsh crocodile ‘Crocodylus palustris’ and the salt water or Estuarine crocodile ‘Crocodylus porosus’.

The biggest number of mugger crocodiles is believed to be found in the Yala or the Ruhuna National Park, according to herpetologists. The Mugger is more like the Alligator with its body shape and features yet still fascinating!

It was in a recent survey conducted by an expert herpetologist of Sri Lanka Anslem de Silva with the assistance from the Department of Wildlife Conservation that revealed over 500 muggers are in Yala. De Silva is also the current Regional Vice Chairman, South Asia and Iran of the Crocodile Specialists Group, IUCN/SSC.

Hunted

In the 20th century, until the Fauna and Flora Protection Act of 1964 was enforced, crocodiles were extensively hunted for their skins and the hunting ended with introduction of the large scale persecution in the Act.

“Historically Sri Lanka had a large number of mugger crocodiles, but during the heights of the leather industry in 1920-30’s, the species was extensively hunted to the point of near extinction,” said Anslem de Silva explaining the current plight of these rough beauties.

Nevertheless, since legal protection was given in 1938, an appreciable number has established, especially within larger tanks (reservoirs) in the dry zone. Mainly a freshwater species, the mugger crocodile is found in lakes, rivers and marshes. Muggers prefer slow-moving, shallower bodies of water rather than fast-flowing, deep areas.

Also known to thrive in man-made reservoirs and irrigation canals and being a large carnivorous reptile, the mugger crocodile eats fish, other reptiles and small mammals, such as monkeys.

In fact, most vertebrates that approach to drink are potential prey, and may suffer being seized and dragged into the water to be drowned and devoured at leisure. Large adults will sometimes prey on large mammals such as deer and the average 450-kg domestic water buffalo.

At night they sometimes hunt on land, lying in ambush near forest trails. This species is generally considered to be occasionally dangerous to humans.A preliminary survey done by De Silva in 2010 in over 100 water bodies indicates that about 130 odd persons were attacked with 35 fatalities. And roughly 80% fatalities were while bathing and washing clothes in tanks. Explaining the attacks made by crocodiles, de Silva said that the Crocodile is a very intelligent animal; it observes its prey for days, even months before attacking.

Alarming

The most alarming factor is that, as a revenge and as a precaution of preventing future attacks over 50 crocodiles were killed! “With the exponential increase of human populations in the dry zone due to large-scale agricultural projects, the number of humans and livestock using these water bodies has also largely increased in the near past.

This sharing of an essential, but a limited resource has resulted in an increase of Human Crocodile Conflict,” said De Silva.

Investigations have revealed that most of the attacks were due to mistakes by the humans themselves.

“The crocodile does not attack spontaneously. It watches the movements on the river banks and even though people have seen crocodiles swimming in the vicinity at a distance they have not really taken it for consideration. People should have either changed the place they use on the river or the tank or else should build a Crocodile Excluding Enclosures,” he explained.

These Crocodile Excluding Enclosures (CEEs) are traditionally used by people living in the southern wet zone of the country where the salt water or estuarine crocodiles inhabit, the herpetologist explained. Yet this does not exist in the dry zone.

“This could be a simple but an effective way of saving lives of humans and livestock and reducing the human-induced mortality of muggers in Sri Lanka,” he added. An earlier study by de Silva in 2008 reveals that at Nilwala river and its tributaries in Southern Sri Lanka a high incidence of saltwater crocodile attacks prevailed: however, all attacks were on people who did not use the traditional CEEs. Dividing the areas used by muggers and humans would be the best solution to save both.

“The direct encounter with humans have resulted in a conflict that have resulted many muggers being killed to make the water sources ‘safe’ for bathing, fishing and other daily needs of humans,” de Silva added.

De Silva and Ruchira Somaweera who is studying for his PhD in the Sydney University, Australia will launch a project to distribute CEEs to extremely needy areas in the dry zone.

Survey

The Chicago Zoological Society’s Chicago Board of Trade Endangered Species Fund for this survey. At present de Silva and the group are collecting details from people living in the dry zone of Sri Lanka on the water bodies that people mostly used where there have been a number of crocodile attacks on humans.

The team calls upon people to inform them on the number of bathing places in their particular village, Name of the water body, locality, approach details, average number of people who use that place per day and the number of people who got attacked by crocodiles to decide on the best place to set up these proposed enclosures. Anslem de Silva could be contacted on 071 2748411 or write to A. de Silva, 15/1 Dolosbage Road, Gampola.

“The enclosures were never experimented in the dry zone and we believe that this will be positive with this crocodile species,” he added.

As he explained, under this program the first step would be installing the CEEs getting the respective community involved in the project and second introduce a system to monitor and maintain a set up and thirdly to increase awareness on the importance of the crocodiles to the eco-system in which the humans have to survive.