An Ancient Oasis for an Apex Predator
The Habarana Tank is a large, man-made reservoir covering about 330 acres in Sri Lanka's dry zone. It is not a modern construction but a part of an ancient and sophisticated hydraulic system. The tank is believed to be the ancient Aggivaddhamanaka reservoir, originally built by King Vasabha between 67-111 A.D. For nearly two millennia, this and thousands of other "wewas," or tanks, have been central to agriculture and daily life. Today, they also have another purpose: as an essential habitat for one of the island's apex predators, the mugger crocodile (Crocodylus palustris).
The mugger is a medium-sized crocodile, with males reaching lengths of 4-5 meters and weighing up to 700 kg. They have the broadest snout of any living species in the genus Crocodylus. Classified as Vulnerable on the IUCN Red List, the species faced significant decline due to hunting for its skin. In Sri Lanka, populations that were common in the 1920s became scarce just a decade later. However, the mugger is remarkably adaptable. It thrives in the slow-moving, freshwaters of these artificial tanks, which provide stable environments for hunting and nesting. The estimated population in Sri Lanka is now between 2,400 and 3,500 individuals, with many inhabiting these ancient irrigation systems.
A Living Laboratory for Coexistence
The wewas of Sri Lanka are not isolated wildlife preserves. They are deeply integrated into human communities, used for bathing, washing clothes, fishing, and irrigating farm fields. This constant proximity has created a unique socio-ecological system where people and large predators share a limited and essential resource. This has made the mugger populations in tanks like Habarana a focus for scientists studying human-wildlife interactions.
Muggers here exhibit behavioral adaptations to the human presence. They are known to dig extensive burrows into the tank bunds and surrounding land, which they use as thermal refuges to escape temperature extremes below 5°C or above 38°C. Their diet is opportunistic, consisting of fish, reptiles, birds, and small mammals. While attacks on humans do occur, the level of coexistence is notable given the density of both human and crocodile populations. Research shows that from 2010 to 2015, mugger crocodiles were responsible for 49 human fatalities across Sri Lanka, indicating that the relationship is complex and not without conflict. The ongoing use of these ancient water bodies by both species provides a dynamic, real-world model for understanding how people and predators can and sometimes cannot share a landscape modified by human engineering for centuries.