Abstract
The Asian water monitor lizard, Varanus salvator, is one of the largest predators in Southeast Asia which persists in human‐dominated landscapes and, as such, is a suitable model to understand the behavioral plasticity of generalists in anthropogenic landscapes. We used Local Convex Hull with adaptive algorithm to estimate the home range size of 14 GPS‐tagged individuals, followed by a MAXENT approach and community prey composition to understand the habitat preferences within the landscape. We estimated larger home ranges in forest than in oil palm plantations, as well as a larger diversity and abundance of mammals. Core home ranges were always linked to water bodies. However, the use of underproductive oil palm, freshwater swamp forest, and degraded forest by monitor lizards were higher than other kind of vegetation. This suitable habitat is proportionally larger in forest (73.7%) than in oil palm plantations (39.6%). Generalized estimation equation models showed that, while full home range size was negatively associated with the abundance of mammals, core areas depicted a positive association with mammal abundance, as well as with the proportion of suitable habitat within the home range. Besides having smaller home ranges in oil palm plantations, our findings suggest that limited suitable habitat availability forces the Asian water monitor lizard's population to establish only one or very few core areas. Contrastingly, under the protection of forest, they have more core areas, widely dispersed within larger home ranges. We conclude that regardless the plasticity of the species, human‐dominated landscapes are altering natural patterns of home range establishment in the monitor lizard's population, creating a potential ecological trap where conditions may not remain favorable for them in the long run. A deeper understanding of the ecological implications on the species and the prey community is advisable.
Highlights
Home range is defined as the area where an individual meets the necessary requirements to perform its ecological functions (Baker, 1978)
95) in forested areas ranged from 0.366 km2 to 1.292 km2 (0.879 ± 0.161), while in oil palm plantations, it varied from 0.066 km2 to 0.742 km2 (0.305 ± 0.095; t = -3.065; p = 0.009)
The present study describes how the Asian water monitor lizard persists in a highly fragmented landscape in Northern Borneo by efficiently reducing their home range when inhabiting oil palm plantations, using areas of high prey abundance, and suitable environmental features
Summary
Home range is defined as the area where an individual meets the necessary requirements to perform its ecological functions (Baker, 1978). The size and distribution of home range is determined by the existent environmental features on the landscape (Dyer et al 2001, Houle et al 2010, Cristescu et al 2016). Human-dominated landscapes usually increase localized food abundance, thereby promoting a reduction of the individuals’ home range (Saïd and Servanty 2005, Smith and Griffith 2009). Home range reduction can translate into a sedentary behaviour, with a more intensive use of resources in the area, including negative impacts on the dynamics of the prey community (Smith and Griffith 2009, Jessop et al 2012). Understanding the home range and habitat preferences of generalist carnivores can provide information about the species plasticity in human-dominated landscapes, and in regards to the distribution and structure of prey communities, with implications for landscape management
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