Varanus salvator


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Varanus salvator
Species Authority: (Laurenti, 1768)
Common Name(s):
English Common Water Monitor
Hydrosaurus salvator (Laurenti, 1768)
Monitor nigricans Cuvier, 1829
Monitor salvator (Laurenti, 1768)
Stellio salvator Laurenti, 1768
Taxonomic Notes: There is significant taxonomic uncertainty surrounding this species complex. The Philippine members of the V. salvator complex have been partly resurrected to species status (V. nuchalis, V. cumingi -with one new subspecies-, V. marmoratus), and partly been described as new species (V. palawanensis, V. rasmusseni) by Koch et al. 2010. If these are validated by gene sequencing work, this would lead to major changes in the conservation assessment due to differences in ecology and national legislation between the taxa (D. Bennett and S. Sweet pers. comm.). In order to reflect this, this assessment includes the following four recognized subspecies:

V. salvator salvator (Laurenti, 1768) from Sri Lanka
V. salvator andamanensis Deraniyagala, 1944, from the Andaman Islands
V. salvator bivittatus (Kuhl, 1820) from Java, Bali, Lombok, Flores, Alor, Wetar and smaller offshore islands
V. salvator macromaculatus Deraniyagala, 1944, from the South East Asian mainland, Sumatra, Borneo, and smaller associated offshore islands.

Water monitors on Sulawesi include V. togianus (Peters, 1872  ) and V. s. celebensis (Schlegel, 1844), and possibly other as-yet undescribed taxa.  Members of the V. salvator complex also occupy the Banggai and Sula islands, and Obi (e.g. Weijola 2010, Weijola and Sweet 2010).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2009-06-30
Assessor(s): Bennett, D., Gaulke, M., Pianka, E.R., Somaweera, R. & Sweet, S.S.
Reviewer(s): Böhm, M., Collen, B. & Ram, M. (Sampled Red List Index Coordinating Team)
Contributor(s): De Silva, R., Milligan, H.T., Wearn, O.R., Wren, S., Zamin, T., Sears, J., Wilson, P., Lewis, S., Lintott, P. & Powney, G.
Varanus salvator has been assessed as Least Concern. This species has a wide distribution, can be found in various habitats, and adapts to habitats disturbed by humans. It is also abundant in parts of its range, despite large levels of harvesting. However, significant taxonomic uncertainty still surrounds this species. While morphological analyses have already started to unravel this taxonomic uncertainty, molecular studies are needed to corroborate this evidence. This is of utmost importance since any future taxonomic changes will also warrant a review of the conservation status of this species.

Geographic Range [top]

Range Description: This species is extremely widespread throughout southern and Southeast Asia (Gaulke and Horn 2004). Varanus salvator salvator is endemic to Sri Lanka, while V. s. macromaculatus occurs throughout southern Asia and Southeast Asia, and as far north as southern China (Koch et al. 2007, Somaweera and Somaweera 2009). It also occurs on Borneo and Sumatra. V. s. andamensis is endemic to the Andaman Islands and V. s. bivittatus occurs on Java and some of the Lesser Sunda islands (Gaulke and Horn 2004, Horn and Gaulke 2004, Koch et al. 2007). Recent work has shown that the species is absent from northeastern Myanmar, northern and northeastern Thailand, all but coastal Cambodia, and all of Laos except for the ranges on the Vietnam border (Cota et al. 2009); it is also absent from northwestern Vietnam, Yunnan, and all but the immediate coastal strip of south China adjacent to Hainan, as well as Timor and Seram and from part of the Lesser Sunda chain (M. Cota and S. Sweet pers. comm.). Although the species has an upper elevational limit of 1,800 m above sea level, it is typically a lowland species which is common only in areas up to 600 m and rare at higher altitudes, particularly above 1,000 m (M. Gaulke pers. comm.).
Bangladesh; Cambodia; China (Guangxi, Hainan, Yunnan); Hong Kong; India (Andaman Is., Nicobar Is.); Indonesia (Bali, Jawa, Kalimantan, Sulawesi, Sumatera); Lao People's Democratic Republic; Malaysia (Peninsular Malaysia); Myanmar; Singapore; Sri Lanka; Thailand; Viet Nam
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species group is thought to be abundant in many places (Gaulke and Horn 2004), including some cities like Bangkok (E. Pianka pers. comm.), but no specific population data exists.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is semi-aquatic and opportunistic and inhabits a variety of natural habitats, such as primary forests and mangrove swamps (Gaulke and Horn 2004, Weijola 2010). The presence of man does not deter these monitors from areas with human disturbance (Gaulke et al. 1999), as they have been reported to thrive in agricultural areas (e.g., rice, oil palm) and even cities with canal systems (e.g. in Sri Lanka, where they are not or hardly disturbed, hunted and prosecuted by man; M. Gaulke pers. comm.) and second-growth forest (S. Sweet pers. comm.). Furthermore, their aquatic habits provide them with a measure of safety (E. Pianka pers. comm.), and their generalist diet may provide added ecological plasticity to this species (Somaweera and Somaweera 2009). In Borneo and Sulawesi, the species in this complex seem to be less tolerant of human activities and do not generally thrive in agricultural regions where there is extensive loss of natural vegetation (S. Sweet pers. comm.).

Although the species may inhabit all the habitats listed above in at least parts of its range, they cannot all be considered equally as important. The habitats considered most important to this species are mangrove vegetation, swamp and wetlands at altitudes of below 1,000 m (Gaulke and Horn 2004).
Systems: Terrestrial

Use and Trade [top]

Use and Trade: This species has been described as one of the most exploited varanids (King and Green 1999, Pernetta 2009). It is mainly hunted because its skin is used in the leather trade, its meat is eaten, and its fat is used in traditional medicine. An estimated 1.5 million skins are traded annually (Herrmann 1999), although the skin trade has decreased slightly since the 1990s. In 1998, the annual allowable catch was set at 454,000 (Auliya et al. 1999), but extensive hunting still occurs in many areas, with national and international protective legislation being ignored. However, the CITES database recorded just over 260,000 individuals traded between 1975 - 2005, from 35 exporting countries (Pernetta 2009). Large numbers of juveniles are exported alive from Indonesia (primarily Java and Sumatra) (S. Sweet pers. comm.). Also, the origin of traded animals remains almost exclusively wild-caught (Pernetta 2009).

Threats [top]

Major Threat(s): The main threat to this species comes from hunting, as the skin of this species is used in the leather trade, its meat is eaten, and its fat is used in traditional medicine. Although in 1998 the annual allowable catch was set at 454,000 (Auliya et al. 1999) and the skin trade has decreased slightly since the 1990s, extensive hunting still occurs in many areas, with national and international protective legislation being ignored. As a result, some populations are likely to go locally extinct. However, in other areas, this species is still abundant (Herrmann 1999, E. Pianka pers. comm.). This resilience may be because of this species' ecological flexibility, high reproductive rates, or the fact that harvesting is mainly concentrated on males (Shine et al. 1996).

Apart from direct utilization of this species, destruction of habitats for oil palm plantations, farming, timber, and firewood have caused declines in population numbers in some areas, particularly in Borneo and Sulawesi, where the species in this complex seem to be less tolerant of human activities and do not generally thrive in agricultural regions (S. Sweet pers. comm.). It is likely that habitat loss was the main reason for population declines in those areas where this species has disappeared (D. Bennett pers. comm.).

In Sri Lanka, the species is not hunted for meat due to the belief that its meat is toxic, but the oil extracted from it is used for traditional medicine and witchcraft. However, this is a very trivial threat compared to the numbers lost from road traffic (R. Somaweera pers. comm.). Since the species can tolerate very polluted habitats, and thrive in areas with high anthropogenic activity, habitat degradation and loss may not be major threats to this species in Sri Lanka (R. Somaweera pers. comm.).

Conservation Actions [top]

Conservation Actions: Parts of this species' distribution range coincide with protected areas; however, the species is reported as absent from Yala National Park in Sri Lanka, possibly caused by the high density of crocodiles in the park (Somaweera and Somaweera 2009). Because of the recent changes of Varanus salvator taxonomy based on morphological analyses, DNA sequencing work is urgently needed to validate the genetic differences between subspecies, which is likely to alter the taxonomy of this species and hence the outcome of future conservation assessments.

Bibliography [top]

Andrews, H.V. 1995. Sexual maturity in Varanus salvator (Laurenti, 1768), with notes on growth and reproductive effort. Herpetological Journal 5: 189-194.

Auliya, M.A. 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.

Cota, M, Chan-Ard, T. and Makchai, S. 2009. Geographical Distribution and Regional Variation of Varanus salvator macromaculatus in Thailand. Biawak 3(4): 134-143.

Gaulke, M. and de Silva, A. 1977. Monitor lizards of Sri Lanka: Preliminary investigations on their population structure. Lyriocephalus 3(1): 1-5.

Gaulke, M. and Horn, H.-G. 2004. Varanus salvator (Nominate Form). In: Pianka, E.R. and King, D.R. (eds), Varanoid lizards of the world, pp. 244-257. Indiana University Press, Bloomington, USA.

Gaulke, M., Erdelen, W. and Abel, F. 1999. A radio-telemetric study of the Water Monitor Lizard (Varanus salvator) in North Sumatra, Indonesia. Mertensiella 11: 63-78.

Herrmann, H.-W. 1999. Husbandry and Captive Breeding of the Water Monitor, Varanus salvator (Reptilia: Sauria: Varanidae) at the Cologne Aquarium (Cologne Zoo). Mertensiella 11: 95-103.

Horn, H.-G. and Gaulke, M. 2004. Varanus salvator (Subspecies). In: Pianka, E.R. and King, D.R. (eds), Varanoid lizards of the world, pp. 258-271. Indiana University Press, Bloomington, USA.

Hudson, R., Alberts, A., Ellis, S. and Byers, O. (eds). 1994. Conservation Assessment and Management Plan for Iguanidae and Varanidae.

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.4). Available at: (Accessed: 27 October 2010).

King, D. and Green B. 1999. Monitors: The Biology of Varanus Lizards. Krieger Publishing Company, Florida.

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. Advances in Monitor Research III. Mertensiella 16: 109.

Koch, A., Gaulke, M. & Böhme, W. 2010. Unravelling the underestimated diversity of Philippine water monitor lizards (Squamata: Varanus salvator complex), with description of two new species and a new subspecies. Zootaxa 2446: 1-54.

Pernetta, A.P. 2009. Monitoring the trade: Using the CITES database to examine the global trade in live monitor lizards (Varanus spp.). Biawak 3(2): 37-45.

Shine, R., Ambariyanto, Harlow, P.S. and Mumpuni. 1998. Ecological traits of commercially harvested water monitors, Varanus salvator, in northern Sumatra. Wildlife Research 25(4): 437-447.

Shine, R. Harlow, P.S. and Keogh, S.J. 1996. Commercial harvesting of giant lizards: the biology of water monitors Varanus salvator in southern Sumatra. Biological Conservation 77: 125-134.

Somaweera, R. and Somaweera, N. 2009. Lizards of Sri Lanka: A Colour Guide with Field Keys. Edition Chimaira, Frankfurt am Main, Germany.

Webb, G.J.W., Vardon M.J. and Boeadi. 1996. An assessment of the harvest levels and status of three species of reptile (Varanus salvator, Python reticulatus and P. curtus) in Indonesia. In: D.J. Kitchener and A. Suyanto (eds), First international conference on Eastern Indonesian-Australian vertebrate fauna, pp. 75-82. Manado, Indonesia.

Weijola, V. S.-Å. 2010. Geographic distribution and habitat use of monitor lizards of the North Moluccas. Biawak 4(1): 7-23.

Weijola, V. S.-Å. and Sweet, S.S. 2010. A new melanistic species of monitor lizard (Reptilia: Squamata: Varanidae) from Sanana Island, Indonesia. Zootaxa 2434: 17-32.

Citation: Bennett, D., Gaulke, M., Pianka, E.R., Somaweera, R. & Sweet, S.S. 2010. Varanus salvator. The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 26 March 2015.
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