Ecology and Health of the Water Monitor Lizard (Varanus salvator) in the Fragmented Landscape of the Lower Kinabatangan Wildlife Sanctuary, Sabah, Malaysia: Population Dynamics, Epidemiological and Toxicological Assessment


PhD researcher: Sergio Guerrero Sánchez
Institution: Cardiff University
Supervisors: Benoit Goossens, Pablo Orozco-terWengel, Pete Kille
Duration: April 2013 – April 2019

The Biawak (Malay word for monitor lizard) Project first started in April 2013 as part of the DGFC action plan to know how different wildlife species adapt to a fragmented landscape within the Lower Kinabatangan Wildlife Sanctuary (LKWS). The LKWS offers an excellent landscape model to understand how different animal species adapt to commercial crops -associated fragmented landscapes and elucidate solutions or alternatives for sustainable land management by offering scientific information that can be used for action plans regarding wildlife conservation. The Asian water monitor lizard (V. salvator) is not considered in danger of extinction, yet this lizard is considered the most hunted monitor lizard in the world because of the pet and skin trade. According to official sources, Indonesia and Malaysia are the biggest monitor lizard skin traders in the world, with more than 420,000 V. salvator skins exported every year between 2005 and 2011. Besides being listed as of “Least Concern” by the IUCN, this species is also listed in the Appendix II of the CITES and in Schedule 2 of the Sabah Wildlife Act (limited hunted under licence).

Despite the high level of extraction to satisfy the international pet and skin trade, the wild populations seem to be stable. Therefore, there is a special interest in knowing how one of the biggest predators in Southeast Asia and successful generalists has adapted to a fragmented landscape driven by the increasing oil palm crops. The abundance of the Asian water monitor lizard in the area, and its tolerance and adaptability to live close to human settlements and crops is a key element that could add special knowledge to the understanding of parasites’ transmission dynamics within an anthropogenic landscape. On the other hand, their particular characteristics as reptiles (long life, periodic skin shedding), as well as the fact that they are scavengers, are important to assess the bioaccumulation process of different pollutants derived from different human activities but especially from the intensive use of agrochemicals in the oil palm production.

The adaptability of the species to live within wild areas and human settlements is an important issue to be assessed in this project in terms of disease transmission between wild and human habitats, as well as in understanding the price that this adaptability carries to the populations in terms of health.

Research questions:
  • What is the size of the salvator’s home range, and how does the landscape define it?
  • Which factors influence the abundance and dispersion of salvator populations in the Kinabatangan floodplain landscape?
  • How do the population dynamics of salvators in this type of landscape influence the presence and transmission of parasites and other pathogens?
  • How does the habitat used by the salvator influence the agrochemicals and heavy metals’ bioaccumulation inside the monitor lizard’s body?

To understand the home range size, habitat preferences and movement patterns, we used GPS/VHF devices (back-packs), which were deployed on the lizards over several months. Aerial photography and Geographical Information System tools were used to analyse the data provided by the devices. All the lizards trapped were measured and sampled. An integral sampling procedure was performed in order to describe the general health of the populations: diet, genetics and microbiological assessment. Toxicological and molecular analyses were also performed to discover how the oil palm plantations’ activities around the LKWS influence the population health of the species. Molecular sexing of individuals was undertaken at the Sabah Wildlife Department Wildlife Health, Genetic and Forensic Laboratory.

water monitor lizard (Varanus salvator)©DGFC
water monitor lizard (Varanus salvator)©DGFC