Asian water monitors (Varanus salvator) remain common in Peninsular Malaysia, despite intense harvesting
Syarifah Khadiejah A , Norazlinda Razak A , Georgia Ward-Fear B , Richard Shine B C and Daniel J. D. Natusch
B C D
+ Author Affiliations
- Author Affiliations
A Department of Wildlife and National Parks, Peninsular Malaysia, KM10 Jalan Cheras 56100, Kuala Lumpur, Malaysia.
B School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia.
C Present address: Department of Biological Sciences, Macquarie University, NSW 2109, Australia.
D Corresponding author. Email: d_natusch_14@hotmail.com
Wildlife Research 46(3) 265-275 https://doi.org/10.1071/WR18166
Submitted: 31 October 2018 Accepted: 18 February 2019 Published: 8 May 2019
Abstract
Context: Each year, between 50 000 and 120 000 Asian water monitors (Varanus salvator, to >2 m total length) are harvested from the wild in Peninsular Malaysia for their skins. Under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), international trade is allowable only if it is sustainable.
Aims: To assess the sustainability of Malaysia’s harvest of water monitors by quantifying the abundance and demography of V. salvator in the wild, and to develop cost-effective methods for estimating the parameters needed to evaluate sustainability.
Methods: We conducted trapping surveys to determine the abundance, population demography and density of V. salvator in four habitat types in five states in Peninsular Malaysia in 2010, 2011, 2012 and 2018.
Key results: Of 1025 lizards captured, only 63% (mostly females) were within the preferred body-size range exploited for commercial trade. Densities were high (37–372 lizards km–2 based on estimated population sizes; 1–35 lizards km–2 based on number of animals captured). Anthropogenic habitats (e.g. oil palm plantations) contained denser populations of monitors than did natural habitats where no hunting occurs, but mean body sizes were smaller.
Conclusions: Despite intensive harvesting for many decades, V. salvator remains abundant and widespread. Harvesting alters the demographic structure of lizard populations, but harvests of V. salvator in Malaysia are likely to be sustainable because a significant proportion of the population is not exploited.
Implications: Ongoing monitoring is required to continually reassess harvest sustainability. For this purpose, relatively simple population approaches, such as line-trapping transects to elucidate relative abundances, can provide important data on the makeup of hunted populations of water monitors more cost-effectively than can mark–recapture studies for assessments of sustainable use of these economically important lizards.
Additional keywords: abundance, CITES, density, hunting, non-detriment, population demographic, sustainable use, wildlife trade.
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