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| NAS - Nonindigenous Aquatic Species |
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Common Name: Water Monitor
Taxonomy: available through 
Identification: A very large lizard that may reach a total length of 2.5 m (exceeding 8 ft) (Minton and Minton, 1973; [Whitaker], 1986; De Lisle, 1996). Adult dorsal coloration is a dark olive with irregular pale, or yellow, spots that may be in transverse rows; often becoming indistinct as the animal ages (De Lisle, 1996; Steel, 1996; Rogner, 1997; Cox et al., 1998). Laterally compressed tail may be banded (De Lisle, 1996). The neck is typically longer than the tapered head. No other lizard indigenous to the U.S. reaches this large size or has this combination of anatomical features. Varanus salvator is illustrated in Smith (1935), Sprackland (1992), De Lisle (1996), Inger and Tan Fui Lian (1996), Steel (1996), Rogner (1997), Bennett (1998), Cox et al. (1998), Gaulke and Horn (2004), Horn and Gaulke (2004), and Pianka et al. (2004).
Size: total length of 2.5 m
Native Range: Throughout most of Southeast Asia, including Malaysia, Indonesia and
its surrounding islands, eastern India, Sri Lanka, the Nicobar Islands,
the Philippines, and southernmost China (Pope, 1935; Smith, 1935;
Daniel, 1983, 2002; [Whitaker], 1986; Zhao and Adler, 1993; De Lisle,
1996; Inger and Tan Fui Lian, 1996; Manthey and Grossmann, 1997;
Rogner, 1997; Bennett, 1998; Cox et al., 1998; Das, 1999; Gaulke and
Horn, 2004; Horn and Gaulke, 2004).
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Hawaii |
Caribbean |
Interactive maps: Continental US, Alaska, Hawaii, Caribbean
Nonindigenous Occurrences: In 1993 a single V. salvator was captured at the Papago Park Ponds, Phoenix, Maricopa County, Arizona (M. Demlong, personal communication 1997). At least one V. salvator has been captured in the Homestead area, Dade County, Florida (Belleville, 1994; Frank and McCoy, 1995). A female V. salvator was collected south of Hwy 92, Deland, Volusia County, Florida (Florida Game and Fresh Water Fish Commission, 1997). Nonindigenous water monitors have been collected from Taiwan (Zhao and Adler, 1993).
Ecology:
The most extensive information on the natural history of these massive lizards is provided by Horn (1994), Shine et al. (1996), Bennett (1998), Gaulke and Horn (2004), Horn and Gaulke (2004), and Pianka (2004). Auffenberg (1994) provides additional information in comparing the ecology of V. salvator with V. bengalensis. The water monitor is a tropical, semiaquatic, omnicarnivorous predator that forages on land and in the water, preying upon invertebrates, carrion, human corpses and feces, and any vertebrate (including fish) it can overpower (Smith, 1935; Daniel, 1983, 2002; De Lisle, 1996; Shine et al., 1996; Steel, 1996; Manthey and Grossmann, 1997; Bennett, 1998; Cox et al., 1998).
They typically shelter in large burrows (Bennett, 1998). The female lays her eggs and buries them in a sheltered locality, such as termitaria (termite mounds), hollow logs, or riverbanks (van der Meer Mohr, 1930; Smith, 1935; [Whitaker], 1986; De Lisle, 1996; Manthey and Grossmann, 1997; Wicker et al., 1999; Gaulke and Horn, 2004; Horn and Gaulke, 2004). Several authors have observed maternal parental care, including nest guarding, in various subspecies and populations of V. salvator (Anonymous, 1978; Biswas and Kar, 1981; Wicker et al., 1999; Somma, 2003; Horn and Gaulke, 2004).
Means of Introduction:
Unknown for Arizona or Florida. Probable pet escapees.
Specimens from Taiwan are thought to be escapees from cargo ships (Zhao and Adler, 1993).
Status:
Not established in the U.S.
Zhao and Adler (1993) do not indicate that V. salvator is established in Taiwan.
Impact of Introduction: None in the U.S. Unknown in Taiwan. The potential impact of these huge, aggressive predators on indigenous wildlife almost certainly would be negative should they establish themselves. Moreover, their size and aggressive behavior makes them potentially dangerous to humans.
Remarks:
The most complete taxonomic summaries are by Ast (2001) and Jennings and Pianka (2004).
While this could be the easiest varanid (monitor) to obtain through the pet trade (Sprackland, 1992; Bennett, 1998), Rogner (1997) recommends that these huge, aggressive lizards only be kept in zoos. Unfortunately, monitor lizards as pet releases/escapees probably represent an increasingly common problem in Florida (Frank and McCoy, 1995; Simberloff, 1997). Water monitors are much exploited for their skin and meat (Shine et al., 1996; Rogner, 1997; Daniel, 2002). Under C.I.T.E.S., V. salvator is listed under Appendix II; international trade is regulated through mandatory permits (Level, 1997; Daniel, 2002).
References
Anonymous. 1978. Varanus salvator breeding at Madras Snake Park. Hamadryad 3(2):4.
Ast, J. C. 2001. Mitochondrial DNA evidence and evolution in Varanoidea (Squamata). Cladistics 17(3):211-226.
Auffenberg, W. 1994. The Bengal Monitor. University Press of Florida, Gainesville. 560 pp.
Belleville, W. 1994. Critter patrol. The Orlando Sentinel (149; 29 May); Florida [news magazine insert] 41(22):8-12, 15.
Bennett, D. 1998. Monitor Lizards. Natural History, Biology & Husbandry. Edition Chimaira (Andreas S. Brahm), Frankfurt am Main. 352 pp.
Biswas, S., and S. Kar. 1981. Some observations on nesting habits and biology of Varanus salvator (Laurenti) of Bhitarkanika Sanctuary, Orissa. Journal of the Bombay Natural History Society 78:303-308.
Cox, M. J., P. P. van Dijk, J. Nabhitabhata, and K. Thirakhupt. 1998. A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand. New Holland Publishers (UK) Ltd, London. 144 pp.
Daniel, J. C. 1983. The Book of Indian Reptiles. Bombay Natural History Society, Bombay. 141 pp.
Daniel, J. C. 2002. The Book of Indian Reptiles and Amphibians. Bombay Natural History Society and Oxford University Press, Mumbai and Oxford. 238 pp.
Das, I. 1999. Biogeography of the amphibians and reptiles of the Andaman and Nicobar Islands, India. Pp. 43-77. In: H. Ota (editor). Tropical Island Herpetofauna. Origin, Current Diversity, and Conservation. Elsevier Science B.V., Amsterdam. 353 pp.
De Lisle, H. F. 1996. The Natural History of Monitor Lizards. Krieger Publishing Company, Malabar, Florida. 201 pp.
Demlong, M. 1997. Personal communicationHerpetologist, Phoenix Zoo, 455 N. Galvin Parkway, Phoenix, Arizona.
Frank, J. H., and E. D. McCoy. 1995. Introduction to insect behavioral ecology: The good, the bad, and the beautiful: Non-indigenous species in Florida. Invasive adventive insects and other organisms in Florida. Florida Entomologist 78(1):1-15.
Gaulke, M., and H.-G. Horn. 2004. Varanus salvator (subspecies). Pp. 258-271. In: E. R. Pianka, D. R. King and R. A. King (editors), Varanoid Lizards of the World. Indiana University Press, Bloomington and Indianapolis. 599 pp.
Horn, H.-G. 1994. Der Ritualkampf von Varanus salvator cumingi. Herpetofauna (Weinstadt) 16(92):27-30.
Horn, H.-G., and M. Gaulke. 2004. Varanus salvator (nominate form). Pp. 244-257. In: E. R. Pianka, D. R. King and R. A. King (editors), Varanoid Lizards of the World. Indiana University Press, Bloomington and Indianapolis. 599 pp.
Inger, R. F., and Tan Fui Lian. 1996. The Natural History of Amphibians and Reptiles in Sabah. Natural History Publications (Borneo) Sdn. Bhd., Kota Kinabalu, Malaysia. 101 pp.
Jennings, W. B., and E. R. Pianka. 2004. Tempo and timing of the Australian Varanus radiation. Pp. 77-87. In: E. R. Pianka, D. R. King and R. A. King (editors), Varanoid Lizards of the World. Indiana University Press, Bloomington and Indianapolis. 588 pp.
Level, J. P. 1997. A Field Guide to Reptiles and the Law. Second Revised Edition. Serpent's Tale Natural History Book Distributors, Lanesboro, Minnesota. 270 pp.
Manthey, U., and W. Grossmann. 1997. Amphibien & Reptilien Südostasiens. Natur und Tier Verlag, Münster. 512 pp.
Minton, S. A., Jr., and M. R. Minton. 1973. Giant Reptiles. Charles Scribner's Sons, New York. 345 pp.
Pianka, E. R. 2004. Evolution of body size and reproductive tactics. Pp. 549-555. In: E. R. Pianka, D. R. King and R. A. King (editors), Varanoid Lizards of the World. Indiana University Press, Bloomington and Indianapolis. 588 pp.
Pianka, E. R., D. R. King, and R. A. King (editors). 2004. Varanoid Lizards of the World. Indiana University Press, Bloomington and Indianapolis. 588 pp.
Pope, C. H. 1935. The Reptiles of China. Turtles, Crocodilians, Snakes, Lizards. Natural History of Central Asia Vol. X. The American Museum of Natural History, New York. 604 pp. + 27 plates.
Rogner, M. 1997. Lizards. Vol. 2. English Edition. Krieger Publishing Company, Malabar, Florida. 308 pp.
Shine, R., P. S. Harlow, and J. S. Keogh. 1996. Commercial harvesting of giant lizards: The biology of water monitors in southern Sumatra. Biological Conservation 77:125-134.
Simberloff, D. 1997. The biology of invasions. Pp. 3-17. In: D. Simberloff, D. C. Schmitz, and T. C. Brown (editors). Strangers in Paradise. Impact and Management of Nonindigenous Species in Florida. Island Press, Washington, D. C. 467 pp.
Smith, M. A. 1935. The Fauna of British India, Including Ceylon and Burma. Reptilia and Amphibia. Vol. II.Sauria. Taylor & Francis Ltd., London. 444 pp. + 1 plate.
Somma, L. A. 2003. Parental Behavior in Lepidosaurian and Testudinian Reptiles. A Literature Survey. Krieger Publishing Company, Malabar, Florida. 174 pp.
Sprackland, R. G. 1992. Giant Lizards. T.F.H. Publications, Inc., Neptune City, New Jersey. 288 pp.
Steel, R. 1996. Living Dragons. A Natural History of the World's Monitor Lizards. Blandford, London. 160 pp.
van der Meer Mohr, J. C. 1930. Over eieren van Varanus salvator en van Python curtus. De Tropische Natuur (Weltevreden, Nedlandsch-Indische) 19(9):156-157.
[Whitaker, R.] 1986. Monitor lizards. Pp. 378-379. In: R. E. Hawkins (editor). Encyclopedia of Indian Natural History. Oxford University Press on behalf of the Bombay Natural History Society, Oxford and Bombay. 620 pp.
Wicker, R., M. Gaulke, and H.-G. Horn. 1999. Contributions to the biology, keeping and breeding of the Mindanao water monitor (Varanus s. cumingi). Mertensiella 11:213-223.
Zhao, Er-mi, and K. Adler. 1993. Herpetology of China. Contributions to Herpetology 10. Society for the Study of Amphibians and Reptiles, Oxford, Ohio. 522 pp.
Other Resources: Photograph courtesy of Ecologyasia.com
Author: Louis A. Somma
Revision Date: 11/18/2004 Citation for this information:
Louis A. Somma. 2010. Varanus salvator. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1086> Revision Date: 11/18/2004
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