| Citation |
Bennett, D., Gaulke, M., Pianka, E.R., Somaweera, R. & Sweet, S.S. . 2010. Varanus salvator. The IUCN Red List of Threatened Species 2010: e.T178214A7499172. https://dx.doi.org/10.2305/IUCN.UK.2010-4.RLTS.T178214A7499172.en. Downloaded on 16 August 2020. |
Description |
JUSTIFICATION
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.
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.).
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).
THREATS
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.).
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).
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. |
