Human-crocodile conflict and conservation implications of Saltwater Crocodiles Crocodylus porosus (Reptilia: Crocodylia: Crocodylidae) in Sri Lanka

A.A. Thasun Amarasinghe, Majintha B. Madawala, D.M.S. Suranjan Karunarathna, S. Charlie Manolis, Anslem de Silva, Ralf Sommerlad


Human-wildlife conflict occurs when human requirements encroach on those of wildlife populations, with potential costs to both humans and wild animals.  As top predators in most inland waters, crocodilians are involved in human-wildlife conflicts in many countries.  Here we present findings of a 5-year survey on human-crocodile conflict on the island of Sri Lanka and relate the results to improving management practices. We aimed to quantify and understand the causes of human-crocodile conflict in Sri Lanka, and propose solutions to mitigate it.  Visual encounter surveys were carried out to estimate the population size of Saltwater Crocodiles. We recorded 778 sightings of Saltwater Crocodiles at 262 of 400 locations surveyed, and estimate the total population to comprise more than 2000 non-hatchlings and to have increased at an average rate of 5% p.a. since 1978. We propose four crocodile vigilance zones within the wet zone and one crocodile vigilance zone within the dry zone of the country. Specific threats to Saltwater Crocodiles identified in crocodile vigilance zones were: habitat destruction and loss; illegal killing and harvesting (17 killings out of fear, ~200 incidents of killing for meat and skins, ~800 eggs annually for consumption); unplanned translocations; and, interaction with urbanization (10 incidents of crocodiles being run over by trains/vehicles and electrocution). Additionally, 33 cases of crocodile attacks on humans were recorded [8 fatal, 25 non-fatal (minor to grievous injuries)] and more than 50 incidents of attacks on farm and pet animals.



Habitat loss; hunting; road kills; policy and planning; translocation; crocodile vigilance zones.

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Allen, G.R. (1974). The Marine Crocodile, Crocodylus porosus, from Ponape, Eastern Caroline Islands, with notes on food habits of crocodiles from the Palau Archipelago. Copeia 1974: 553.

Amarasinghe, A.A.T., D.M.S.S. Karunarathna, J. Hallermann, J. Fujinuma, H. Grillitsch & P.D. Campbell (2014). A new species of the genus Calotes (Squamata: Agamidae) from high elevations of the Knuckles Massif of Sri Lanka. Zootaxa 3785: 59–78.

Anand, V.V., S. Senadheera & T. Rupatunge (2013). A view on Saltwater Crocodile (Crocodylus porosus) captured from anthropogenic habitats in western province, Sri Lanka, pp. 258–260. In: Crocodiles. Proceedings of the 22nd Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Anderson, J. & F. Pariela (eds.) (2005). Strategies to Mitigate Human-Wildlife Conflict in Mozambique. Report for the National Directorate of Forests and Wildlife, Mozambique. Food and Agriculture Organization of the United Nations, Rome, Italy.

Bahir, M.M. & D.E. Gabadage (2009). Taxonomic and scientific inaccuracies in a consultancy report on biodiversity: a cautionary note. Journal of Threatened Taxa 1(6): 317–322;

Bayliss, P., G.J.W. Webb, P.J. Whitehead, K.E. Dempsey & A.M.A. Smith (1986). Estimating the abundance of Saltwater Crocodiles, Crocodylus porosus Schneider in tidal wetlands of the N.T.: A mark-recapture experiment to correct spotlight counts to absolute numbers and the calibration of helicopter and spotlight counts. Australian Wildlife Research 13: 309–320.

Beehler, B.M. (2011). Editorial: Natural History Today and Tomorrow. Taprobanica 3: 50–51.

Brien, M.L., M.A. Read, H.I. McCallum & G.C. Grigg (2008). Home range and movements of radio-tracked Estuarine Crocodiles (Crocodylus porosus) within a non-tidal waterhole. Wildlife Research 35: 140–149.

Caldicott, D.G.E., D. Croser, C. Manolis, G. Webb & A. Britton (2005). Crocodile attacks in Australia. An analysis of its incidence, and review of the pathology and management of crocodilian attacks in general. Wilderness and Environmental Medicine 16(3): 143–159.

Caljouw, M., P.J.M. Nas & Pratiwo (2005). Flooding in Jakarta: Towards a blue city with improved water management. Bijdragen tot de Taal- Land- en Volkenkunde 161(4): 454–484.

Campbell, H.A., R.G. Dwyer, T.R. Irwin & C.E. Franklin (2013). Home range utilisation and long-range movement of estuarine crocodiles during the breeding and nesting season. PLoS ONE 8(5): e62127.

Campbell, H.A., R.G. Dwyer, H. Wilson, T.R. Irwin & C.E. Franklin (2014). Predicting the probability of large carnivore occurance: a strategy to promote crocodile and human coexistance. Animal Conservation (early view);

Cincotta, R.P., J. Wisnewski & R. Engelman (2000). Human populations in the biodiversity hotspots. Nature 404: 990–992.

CFAZ (Crocodile Farmers Association of Zimbabwe) (2012). Codes of Practice. CFAZ, Harare, Zimbabwe.

Cooper, P.H. & R.W.G. Jenkins (1993). Natural history of the Crocodylia. pp. 337–349. In: Glasby, C.J., G.J.B. Ross & P.L. Beesley (eds.). Fauna of Australia, Amphibia and Reptilia. Australian Government Publishing Service, Canberra, Australia.

CSG (Crocodile Specialist Group) (2015a). Human-Crocodile Conflict; Crocodile Exclusion Enclosures (CEEs).

CSG (Crocodile Specialist Group) (2015b). Sustainable utilization.

Deraniyagala, P.E.P. (1939). The Tetrapod Reptiles of Ceylon, Testudinates and Crocodilians. National Museums of Sri Lanka, Colombo, Sri Lanka, 412.

de Silva, A. (2008). Preliminary survey of Saltwater Crocodiles (Crocodylus porosus) in the Nilwala River, Sri Lanka. Crocodile Specialist Group Newsletter 27: 10–13.

de Silva, A. (2013). The Crocodiles of Sri Lanka (Including Archaeology, History, Folklore, Traditional Medicine, Human-Crocodile Conflict and a Bibliography of the Literature on Crocodiles of Sri Lanka). AMP Print Shop, Gampola, Sri Lanka.

de Silva, A. & J. Lenin (2010). Mugger Crocodile Crocodylus palustris. pp. 94–98. In: Manolis, S.C. & C. Stevenson (eds.). Crocodiles. Status Survey and Conservation Action Plan. Crocodile Specialist Group, Darwin, Australia.

de Silva, M. & A. de Silva (2008). Record of Crocodylus porosus nest from Sri Lanka. Crocodile Specialist Group Newsletter 27: 13–14.

Devapriya, W.S. (2004). A survey of the Saltwater Crocodile (Crocodylus porosus) in the Muthurajawela urban marsh. Lyriocephalus 5: 25–26.

Erickson, G.M., P.M. Gignac, S.J. Steppan, A.K. Lappin, K.A. Vliet, Breuggen, J.D., Inouye, B.D., Kledzik, D. and G.J.W. Webb (2012). Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation. PlosOne 7: e31781.

Gramentz, D. (2008). The distribution, abundance and threat of the Saltwater Crocodile, Crocodylus porosus, in the Bentota Ganga, Sri Lanka, 16pp.

Hanson, J.O., S.W. Salisbury, H.A. Campbell, R.G. Dwyer, T.D. Jardine & C.E. Franklin (2014). Feeding across the food web: The interaction between diet, movement and body size in estuarine crocodiles (Crocodylus porosus). Austral Ecology (early view);

Hutton, J. & G. Webb (2002). Legal trade snaps back: using the experience of crocodilians to draw lessons on regulation of the wildlife trade, pp. 1–10. In: Crocodiles. Proceedings of the 16th Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Jayawardene, J. (2004). Conservation and management of the two species of Sri Lankan Crocodiles (Crocodylus porosus and Crocodylus palustris). pp. 155–165. In: Crocodiles. Proceedings of the 17th Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Karunarathna, D.M.S.S., A.A.T. Amarasinghe, D.E. Gabadage, M.M. Bahir & L.E. Harding (2010). Current status of faunal diversity in Bellanwila-Attidiya Sanctuary, Colombo District, Sri Lanka. Taprobanica 2: 48–63.

Kay, W.R. (2004). Movements and home ranges of radio-tracked Crocodylus porosus in the Cambridge Gulf region of Western Australia. Wildlife Research 31: 495–508.

Lamarque, F., J. Anderson, R. Fergusson, M. Lagrange, Y. Osei-Owusu & L. Bakker (2009). Human-wildlife conflict in Africa: Causes, consequences and management strategies. Food and Agriculture organization of the United Nations, Rome, Italy, 98pp.

Letnic, M. & G. Connors (2006). Changes in the distribution and abundance of Saltwater Crocodiles (Crocodylus porosus) in the upstream, freshwater reaches of rivers in the Northern Territory, Australia. Wildlife Research 33: 529–538.

Manolis, C. (2005). Long-distance movement by a Saltwater Crocodile. Crocodile Specialist Group Newsletter 24: 18.

McGregor, J. (2005). Crocodile crimes: people versus wildlife and the politics of postcolonial conservation on Lake Kariba, Zimbabwe. Geoforum 36: 353–369.

MOE (2012). The National Red List 2012 of Sri Lanka: Conservation Status of the Fauna and Flora. Ministry of Environment, Colombo, Sri Lanka: 476.

NRMMC (Natural Resource Management Ministerial Council) (2009). Code of Practice for the Humane Treatment of Wild and Farmed Australian Crocodiles. NRMMC, Canberra, Australia.

Pethiyagoda, R., N. Gunatilleke, M. de Silva, S. Kotagama, S. Gunatilleke, P. de Silva, M. Meegaskumbura, P. Fernando, S. Ratnayeke, J. Jayewardene, D. Raheem, S. Benjamin & A. Ilangakoon (2007). Science and biodiversity: the predicament of Sri Lanka. Current Science 92: 426–427.

Porej, D. (2004). A case study of the Saltwater Crocodile Crocodylus porosus in Muthurajawela Marsh, Sri Lanka - Considerations for conservation. Journal of Bombay Natural History Society 101: 337–343.

Rao, M.V.S. (1996). Nesting behaviour of the Indian crocodiles, Gavialis gangeticus, Crocodylus palustris and Crocodylus porosus, pp. 212–216. In: Ramamurthi, R. & Geetabali (eds.). Readings in Behaviour. Newage International Ltd, New Delhi, India.

RDA (2007). National Road Master Plan of Sri Lanka 2007–2017. Road Development Authority, Government of Sri Lanka, Colombo, Sri Lanka, 37pp.

Read, M.A., G.C. Grigg, S.R. Irwin, D. Shanahan & C.E. Franklin (2007). Satellite tracking reveals long distance coastal travel and homing by translocated Estuarine Crocodiles, Crocodylus porosus. PlosOne 2: e949.

Samarasinghe, D.J.S. (2014). The Human-Crocodile Conflict in Nilwala River, Matara (Phase 1). YZA Publications, Dehiwala, Sri Lanka, 86pp.

Santiapillai, C. & M. de Silva (2001). Status, distribution and conservation of crocodiles in Sri Lanka. Biological Conservation 97: 305–318.

Santiapillai, C., S. Wijeyamohan, R. Vandercone & R. Somaweera (2004). Crocodiles of Sri Lanka. Mannar District Rehabilitation and Reconstruction through Community Approach Project (www.

Senanayake, N. (1995). Human and reptile conflicts: impact on reptiles in Sri Lanka. Lyriocephalus 2: 86.

Somaweera, R. & A. de Silva (2013). Using traditional knowledge to minimize human-crocodile conflict in Sri Lanka, pp. 257. In: Crocodiles. Proceedings of the 22nd Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Taylor, J.A. (1979). The foods and feeding habits of subadult Crocodylus porosus Schneider in northern Australia. Australian Wildlife Research 6: 347–359.

Uragoda, C.G. (1994). Wildlife Conservation Sri Lanka. Wildlife and Nature Protection Society, Colombo, Sri Lanka, 162pp.

Walsh, B. & P.J. Whitehead (1993). Problem crocodiles, Crocodylus porosus, at Nhulunbuy, Northern Territory: an assessment of relocation as a management strategy. Wildlife Research 20: 127–135.

Webb, G.J.W. (2000). Sustainable use of large reptiles - an introduction to issues. pp. 413–430. In: Crocodiles. Proceedings of the 15th Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Webb, G.J.W., M.L. Dillon, G.E. McLean, S.C. Manolis & B. Ottley (1990). Monitoring the recovery of the Saltwater Crocodile (Crocodylus porosus) population in the Northern Territory of Australia. pp. 329–380. In: Crocodiles. Proceedings of the 9th Working Meeting of the IUCN-SSC Crocodile Specialist Group. IUCN, Gland, Switzerland.

Webb, G. & C. Manolis (1989). Crocodiles of Australia. Reed Books, Frenchs Forest, Australia,

Webb, G.J.W. & H. Messel (1978). Movement and dispersal patterns of Crocodylus porosus in some rivers of Arnhem Land, northern Australia. Australian Wildlife Research 5: 263–283.

Whitaker, R. (2004). Regional report from CSG Vice Chairman for South Asia. Crocodile Specialist Group Newsletter 23: 8–9.

Whitaker, R. & N. Whitaker (2008). Who’s got the biggest? Crocodile Specialist Group Newsletter 27: 26–30.

Whitaker, R. & Z. Whitaker (1977). Sri Lanka crocodile survey. Loris 14: 239–241.

Whitaker, R. & Z. Whitaker (1979). Preliminary crocodile survey - Sri Lanka. Journal of Bombay Natural History Society 76: 66–85.

Wittemyer, G., P. Elsen, W.T. Bean, A.C.O. Burton & J.S. Brashares (2008). Accelerated human population growth at protected area edges. Science 321: 123–126.

Woodroffe, R., S. Thirgood & A. Rabinowitz (2005). People and Wildlife: Conflict or Coexistence. Cambridge University Press, UK, 516pp.



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