Ecological and behavioural traits of the Sri Lankan water monitor (Varanus salvator) in an urban landscape of Western Province, Sri LankaSuranjan Karunarathna A , Thilina Surasinghe B F , Majintha Madawala A C , Ruchira Somaweera D and A. A. Thasun Amarasinghe E
A Nature Explorations and Education Team, Number B-1/G-6, De Soysapura, Moratuwa 10400, Sri Lanka.
B Department of Biological Sciences, Bridgewater State University, Bridgewater, MA 02325, USA.
C South Australian Herpetology Group, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia.
D Ecosystem Change Ecology Team, CSIRO Land and Water, 147, Underwood Avenue, Floreat, WA 6014, Australia.
E Research Center for Climate Change, University of Indonesia, Gedung Pusat Administrasi Universitas (PAU) Lantai 8.5, Kampus UI, Depok 16424, Indonesia.
F Corresponding author. Email: firstname.lastname@example.org
Marine and Freshwater Research 68(12) 2242-2252 https://doi.org/10.1071/MF17038
Submitted: 3 February 2017 Accepted: 16 April 2017 Published: 6 July 2017
The Asian water monitor Varanus salvator is one of the largest species of lizard in the world and is widespread on the island of Sri Lanka. In the present study, we conducted a 7-month survey within a 5-km stretch in the urbanised Attanagalu-Oya river area to study habitat associations, mesohabitat use and behaviour of V. salvator in urban landscapes. The greatest number of monitor sightings was made in aquatic habitats, followed by terrestrial and arboreal habitats within the riparian zone. Sightings of different life history stages of V. salvator across major habitat types varied significantly. The adults and subadults associated mostly with aquatic and terrestrial habitats, whereas hatchlings and juveniles associated mostly with aquatic and arboreal habitats. Given variable sighting frequencies of distinct life history stages across different major habitat types, it is likely that there is substantial age-structured niche partitioning in V. salvator. The urban population of V. salvator studied seemed to be fairly abundant, and resilient to anthropogenic stressors and adversity of urbanisation. In species-depauperate urban environments, ecosystem functions provisioned by V. salvator as generalist predators as well as scavengers are arguably significant and deserve further investigation. No direct anthropogenic threats were observed during the study.
Additional keywords: adaptability, conservation, habitat generalist, urban environment, varanid lizards.
ReferencesAmarasinghe, A. A. T., Chathuranga, G., and Karunarathna, D. M. S. S. (2009). Varanus salvator (Laurenti, 1768) in Rathgama Lagoon in Galle District, Sri Lanka. Biawak 3, 81–84.
Anderson, M. J. (2001). A new method for non‐parametric multivariate analysis of variance. Austral Ecology 26, 32–46.
Auliya, M., and Erdelen, W. (1999). A field study of the water monitor lizard (Varanus salvator) in West Kalimantan, Indonesia – new methods and old problems. Mertensiella 11, 247–266.
Barrett, K., and Guyer, C. (2008). Differential responses of amphibians and reptiles in riparian and stream habitats to land use disturbances in western Georgia, USA. Biological Conservation 141, 2290–2300.
| Differential responses of amphibians and reptiles in riparian and stream habitats to land use disturbances in western Georgia, USA.CrossRef |
Böhme, W. (2003). Checklist of the living monitor lizards of the world (family Varanidae). Zoölogische Verhandelingen – Uitgegeven door het Rijksmuseum van Natuurlijke Historie te Leiden 341, 4–43.
Bozec, Y.-M., Kulbicki, M., Laloë, F., Mou-Tham, G., and Gascuel, D. (2011). Factors affecting the detection distances of reef fish: implications for visual counts. Marine Biology 158, 969–981.
| Factors affecting the detection distances of reef fish: implications for visual counts.CrossRef |
Cota, M., Chan-Ard, T., and Makchai, S. (2009). Geographical distribution and regional variation of Varanus salvator macromaculatus in Thailand. Biawak 3, 134–143.
Das, I., and De Silva, A. (2005). ‘A Photographic Guide to Snakes and Other Reptiles of Sri Lanka.’ (New Holland: Sydney, NSW, Australia.)
Deraniyagala, P. E. P. (1953). ‘A Coloured Atlas of Some Vertebrates from Ceylon. Tetrapod Reptilia, Volume 2, National Museums of Sri Lanka.’ (The Ceylon Government Press: Colombo, Sri Lanka.)
Dryden, G., Green, B., Wikramanayake, E. D., and Dryden, K. (1992). Energy and water turnover in two tropical varanid lizards, Varanus bengalensis and V. salvator. Copeia 1992, 102–107.
| Energy and water turnover in two tropical varanid lizards, Varanus bengalensis and V. salvator.CrossRef |
Dudgeon, D. (2000). Riverine biodiversity in Asia: a challenge for conservation biology. Hydrobiologia 418, 1–13.
| Riverine biodiversity in Asia: a challenge for conservation biology.CrossRef |
Erdelen, W. (1991). Conservation and population ecology of monitor lizards: the water monitor Varanus salvator (Laurenti, 1768) in south Sumatra. Mertensiella 2, 120–135.
Faunce, C. H., and Serafy, J. E. (2007). Nearshore habitat use by gray snapper (Lutjanus griseus) and bluestriped grunt (Haemulon sciurus): environmental gradients and ontogenetic shifts. Bulletin of Marine Science 80, 473–495.
Gaulke, M. (1992). Taxonomy and biology of Philippine water monitors (Varanus salvator). Philippine Journal of Science 121, 345–381.
Gaulke, M., and De Silva, A. (1997). Monitor lizards of Sri Lanka: preliminary investigation on their population structure. Lyriocephalus 3, 1–5.
Gaulke, M., Erdelen, W., and Abel, F. (1999). A radiotelemetric study of the water monitor lizard (Varanus salvator) in North Sumatra, Indonesia. Mertensiella 11, 63–78.
Gaulke, M., Horn, H., Pianka, E., and King, D. (2004). Varanus salvator (nominate form). In ‘Varanoid Lizards of the World’. (Eds E. R. Pianka, K. Dennis, and R. A. King.) pp. 244–257. (Indiana University Press: Bloomington, IN, USA.)
Greenberg, C. H. (2001). Response of reptile and amphibian communities to canopy gaps created by wind disturbance in the southern Appalachians. Forest Ecology and Management 148, 135–144.
| Response of reptile and amphibian communities to canopy gaps created by wind disturbance in the southern Appalachians.CrossRef |
Grimm, N. B., Foster, D., Groffman, P., Grove, J. M., Hopkinson, C. S., Nadelhoffer, K. J., Pataki, D. E., and Peters, D. P. (2008). The changing landscape: ecosystem responses to urbanization and pollution across climatic and societal gradients. Frontiers in Ecology and the Environment 6, 264–272.
| The changing landscape: ecosystem responses to urbanization and pollution across climatic and societal gradients.CrossRef |
Guarino, F. (2002). Spatial ecology of a large carnivorous lizard, Varanus varius (Squamata: Varanidae). Journal of Zoology 258, 449–457.
| Spatial ecology of a large carnivorous lizard, Varanus varius (Squamata: Varanidae).CrossRef |
Halwatura, D., Najim, M., and Udayanga, N. (2013). Impacts of urban water management in Attanagalu Oya Basin. In ‘Special Session on Urban Water Environment Monitoring & Management, 4th International Conference on Structural Engineering and Construction Management’, 13–15 December 2013, Kandy, Sri Lanka. (Eds K. P. P. Pahtirana, T. Jayasinghe, R. Dissanayake, and P. Mendis.) pp. 134–145. (Nethwin Printers: Kandy, Sri Lanka.)
Horn, H., Gaulke, M., Pianka, E., King, D., and King, R. (2004). Varanus salvator (subspecies). In ‘Varanoid Lizards of the World’. (Eds E. R. Pianka, K. Dennis, and R. A. King.) pp. 258–271. (Indiana University Press: Bloomington, IN, USA.)
Johnson, P. D., and Brown, K. M. (2000). The importance of microhabitat factors and habitat stability to the threatened Louisiana pearl shell, Margaritifera hembeli (Conrad). Canadian Journal of Zoology 78, 271–277.
| The importance of microhabitat factors and habitat stability to the threatened Louisiana pearl shell, Margaritifera hembeli (Conrad).CrossRef |
Karunarathna, D. M. S. S., Amarasinghe, A. A. T., and De Vos, A. (2008). Preliminary notes on the monitor lizards (Family: Varanidae) within the national Zoological Gardens, Dehiwala, Colombo district, Sri Lanka. Biawak 2, 109–118.
Koch, A., Auliya, M., Schmitz, A., Kuch, U., and Böhme, W. (2007). Morphological studies on the systematics of South East Asian water monitors (Varanus salvator Complex): nominotypic populations and taxonomic overview. Mertensiella 16, 109–180.
Koch, A., Auliya, M., and Ziegler, T. (2010). Updated checklist of the living monitor lizards of the world (Squamata: Varanidae). Bonn Zoological Bulletin 57, 127–136.
Koch, A., Ziegler, T., Boehme, W., Arida, E., and Auliya, M. (2013). Pressing problems: distribution, threats, and conservation status of the monitor lizards (Varanidae: Varanus spp.) of Southeast Asia and the Indo-Australian Archipelago. Herpetological Conservation and Biology 8, 1–62.
Kulabtong, S., and Mahaprom, R. (2014). Observation on food items of Asian water monitor, Varanus salvator (Laurenti, 1768) (Squamata Varanidae), in urban eco-system, Central Thailand. Biodiversity Journal 6, 695–698.
Lauprasert, K., and Thirakhupt, K. (1999). Species diversity, distribution and morphological differences of monitor lizards (Family Varanidae) in southern Thailand. The Natural History Journal of Chulalongkorn University 1, 39–46.
Mayes, P. J. (2006). The ecology and behaviour of Varanus mertensi (Reptilia: Varanidae). Ph.D. Thesis, Edith Cowan University, Joondalup, WA, Australia.
McKinney, M. L. (2002). Urbanization, biodiversity, and conservation. Bioscience 52, 883–890.
| Urbanization, biodiversity, and conservation.CrossRef |
McKinney, M. L., and Lockwood, J. L. (1999). Biotic homogenization: a few winners replacing many losers in the next mass extinction. Trends in Ecology & Evolution 14, 450–453.
| Biotic homogenization: a few winners replacing many losers in the next mass extinction.CrossRef | 1:STN:280:DC%2BC2sbgvFGktw%3D%3D&md5=41e526a026e9ecf3ba75fae7469a9c3fCAS |
Nichols, J. D., Bailey, L. L., O’Connell, A. F., Talancy, N. W., Grant, E. H. C., Gilbert, A. T., Annand, E. M., Husband, T. P., and Hines, J. E. (2008). Multi-scale occupancy estimation and modelling using multiple detection methods. Journal of Applied Ecology 45, 1321–1329.
| Multi-scale occupancy estimation and modelling using multiple detection methods.CrossRef |
Ovaska, K., Sopuck, L., Engelstoft, C., Matthias, L., Wind, E., and MacGarvie, J. (2004). Best Management practices for amphibians and reptiles in urban and rural environments in British Columbia. Ecosystem Standards and Planning Biodiversity Branch, British Columbia Ministry of Water, Land and Air Protection, Nanaimo, BC, Canada.
Pandav, B., and Choudhury, B. (1996). Diurnal and seasonal activity patterns of water monitor (Varanus salvator) in the Bhitarkanika mangroves, Orissa, India. Hamadryad 21, 4–12.
Pathirana, C., Bandara, N., Jayaweera, C., and Fonseka, W. F. (2010). Suitability of Attanagalu Oya as a drinking water source. In ‘Proceedings of International Forestry and Environment Symposium’, 26–27 November 2012, Nugegoda, Sri Lanka. (Eds D. M. H. S. K. Ranasinghe, B. M. P. Singhakumara, H. S. Amarasekera, N. J. G. J. Bandara, U. A. D. P. Gunawardana, and S. M. C. U. P. Subasinghe.) pp. 70–75. (Department of Forestry and Environmental Science, University of Sri Jayewardenepura: Nugegoda, Sri Lanka.)
Pepin, D. J. (2001). Natural history of monitor lizards (family Varanidae) with evidence from phylogeny, ecology, life history and morphology. Ph.D. Thesis, Washington University, St Louis, MO, USA.
Perry, G., and Garland, T. (2002). Lizard home ranges revisited: effects of sex, body size, diet, habitat, and phylogeny. Ecology 83, 1870–1885.
| Lizard home ranges revisited: effects of sex, body size, diet, habitat, and phylogeny.CrossRef |
Pianka, E. R. (1969). Sympatry of desert lizards (ctenotus) in western-Australia. Ecology 50, 1012–1030.
| Sympatry of desert lizards (ctenotus) in western-Australia.CrossRef |
Pianka, E. R., King, D., and King, R. A. (2004). ‘Varanoid Lizards of the World.’ (Indiana University Press: Bloomington, IN, USA.)
Polis, G. A. (1984). Age structure component of niche width and intraspecific resource partitioning: can age groups function as ecological species? American Naturalist 123, 541–564.
| Age structure component of niche width and intraspecific resource partitioning: can age groups function as ecological species?CrossRef |
Randow, H. (1932). Fauna und Flora von Dehiwala auf Ceylon. Wochenschrift für Aquarien- und Terrarienkunde 29, 471–473.
Rathnayake, N., Herath, N., Hewamathes, K., and Jayalath, S. (2003). The thermal behaviour, diurnal activity pattern and body temperature of Varanus salvator in Central Sri Lanka. Hamadryad 27, 179–184.
Samarakoon, J., and Renken, H. (1999). ‘Wetland Atlas of Sri Lanka.’ (CEA/ARCADIS Euroconsult: Colombo, Sri Lanka.)
Shine, R., Harlow, P. S., and Keogh, J. S. (1996). Commercial harvesting of giant lizards: the biology of water monitors Varanus salvator in southern Sumatra. Biological Conservation 77, 125–134.
| Commercial harvesting of giant lizards: the biology of water monitors Varanus salvator in southern Sumatra.CrossRef |
Smith, G. R., and Ballinger, R. E. (2001). The ecological consequences of habitat and microhabitat use in lizards: a review. Contemporary Herpetology 3, 1–37.
Somaweera, R., and Somaweera, N. (2009). ‘Lizards of Sri Lanka: a Colour Guide with Field Keys.’ (Edition Chimaira/Serpent’s Tale NHBD: Frankfurt, Germany.)
Sudasinghe, H., Suranga, P., and Karunarathna, D. M. S. S. (2015). Fish die-off in the Attanagalu-Oya River, Sri Lanka: a provisional checklist of icthyofauna. Taprobanica 7, 49–52.
| Fish die-off in the Attanagalu-Oya River, Sri Lanka: a provisional checklist of icthyofauna.CrossRef |
Sutherland, D. R. (2011). Dietary niche overlap and size partitioning in sympatric varanid lizards. Herpetologica 67, 146–153.
| Dietary niche overlap and size partitioning in sympatric varanid lizards.CrossRef |
Træholt, C. (1995). Notes on the burrows of the water monitor lizard, Varanus salvator. Malayan Nature Journal 49, 103–112.
Uyeda, L. (2009). Garbage appeal: relative abundance of water monitor lizards (Varanus salvator) correlates with presence of human food leftovers on Tinjil Island, Indonesia. Biawak 3, 9–17.
Uyeda, L. T., Iskandar, E., Kyes, R. C., and Wirsing, A. J. (2015). Encounter rates, agonistic interactions, and social hierarchy among garbage-feeding water monitor lizards (Varanus salvator bivittatus) on Tinjil Island, Indonesia. Herpetological Conservation and Biology 10, 753–764.
Weijola, V. S.-Å. (2010). Geographical distribution and habitat use of monitor lizards of the north Moluccas. Biawak 4, 7–23.
Welton, L. J., Wood, P. L., Oaks, J. R., Siler, C. D., and Brown, R. M. (2014). Fossil-calibrated phylogeny and historical biogeography of Southeast Asian water monitors (Varanus salvator Complex). Molecular Phylogenetics and Evolution 74, 29–37.
| Fossil-calibrated phylogeny and historical biogeography of Southeast Asian water monitors (Varanus salvator Complex).CrossRef |
Wijesekara, R., and Kudahetty, C. (2009). Preliminary groundwater assessment and water quality study in the shallow aquifer system in the Attanagalu Oya Basin. In ‘Proceedings of National Conference on Water, Food Security and Climate Change in Sri Lanka. Water Quality, Environment and Climate Change’, 9–11 June 2009. (Eds A. Evans and K. Jinapala.) pp. 77–87. (International Water Management Institute: Colombo, Sri Lanka.)
Wikramanayake, E. D., and Dryden, G. L. (1993). Thermal ecology of habitat and microhabitat use by sympatric Varanus bengalensis and V. salvator in Sri Lanka. Copeia 1993, 709–714.
| Thermal ecology of habitat and microhabitat use by sympatric Varanus bengalensis and V. salvator in Sri Lanka.CrossRef |
Wikramanayake, E. D., and Green, B. (1989). Thermoregulatory influences on the ecology of two sympatric varanids in Sri Lanka. Biotropica 21, 74–79.
| Thermoregulatory influences on the ecology of two sympatric varanids in Sri Lanka.CrossRef |