Dietary notes and foraging ecology of south-east Asian water monitors (Varanus salvator) in Sabah,northern Borneo, Malaysia

摘要

The South-east Asian water monitor (Varanus salvator) is one of the largest and most widely distributed lizard species in the world occurring from Sri Lanka to the Moluccas （Koch et al.,2007; Somaweera & Somaweera, 2009; Koch & B?hme,2010). Despite its widespread distribution, and being considered an apex predator in many of the ecosystems it inhabits, particularly east of the Sunda shelf where large carnivorous mammals are generally absent (Sweet & Pianka, 2007),little is known about the functional ecology of water monitors. Typically regarded as generalist carnivores, they have been observed feeding on a huge variety of prey ranging from invertebrates, crustaceans and vertebrates including frogs, snakes, birds, fish, squirrels, deer, crocodiles, rats and tortoises (Gadow, 1901; Smith, 1932; Losos & Greene,1988; Gaulke, 1991), to carrion, human refuse, fermented coconut and even human corpses (Uyeda, 2009; Guawardenam, 2016; Koch & Arida, 2017). From such records it can be deduced that water monitors provide integral ecosystem services through regulation of prey populations and carrion removal which is important in disease dynamics and nutrient cycling (Wilson & Wolkovich,2011; Moleon et al., 2015; Twining et al., 2017). However, the effects of land-use change on ecological role of the species remains unclear, as wild-living water monitors are typically highly mobile and alert making direct observations difficult.