SEAVR 2019: 054‐055
ISSN: 2424‐8525
Date of publication: 25 April 2019
Hosted online by ecologyasia.com

Predation on a Bronzeback snake by a Palawan Water Monitor Lizard
Varanus palawanensis on Miniloc Island, Philippines
Bianca Kaye C. ONG & Emerson Y. SY
emersonsy@gmail.com (Sy)Observer: Bianca Kaye C. Ong.
Photograph by: Bianca Kaye C. Ong.
Subjects identified by: Emerson Y. Sy.
Location: Miniloc Island, Barangay Bebeladan, Municipality of El Nido, Palawan Province, Philippines.
Elevation: 1 metre asl.
Habitat: Beach area of a resort, approximately five metres away from the shore.
Date and time: 30 January 2019, 11:00 hrs.
Identity of subjects:i) Palawan Water Monitor, Varanus palawanensis (Reptilia: Squamata: Varanidae).
ii) Bronzeback snake, Dendrelaphis sp. (Reptilia: Squamata: Colubridae).
Description of record: A juvenile monitor lizard (estimated snout‐vent length of 46 cm) was observed biting a snake(estimated total length of 100 cm) near the tail while violently thrashing its head from side to side to reposition its
bite closer to the head of the snake (Fig. 1). The lizard eventually bit the head and swallowed the prey head first. It
took the lizard 30 minutes to completely consume the whole snake.

Fig. 1.

© Bianca Kaye C. Ong54

Remarks: The snake was identified as Dendrelaphis sp., possibly of the D. caudolineatus group, based on (i) dorsal
body colour is olive brown, (ii) nine supralabial scales, 5th and 6th in contact with eye, 7th triangular‐shaped, 9thlargest, (iii) head is longer than it is wide, and is distinct from the neck and (iv) reddish‐orange colour on the neckarea (van Rooijen & Vogel, 2012). The lizard was identified as Varanus palawanensis based on (i) head colour is
predominantly black, (ii) an off‐white temporal stripe, (iii) throat is off‐white with black spots, (iv) enlarged nuchal
scales and (v) dorsal colour is mainly black with some yellowish scales (Koch et al., 2010).
The Palawan Water Monitor is endemic to the Philippines and has been documented on the following islands:
Balabac, Busuanga, Calauit, Candaraman, Coron, Lagen, Malapina, Palawan, and Sibutu (Koch et al. 2010, Sy &Dichaves, unpubl. data). Water monitors are active hunters which feed on eggs (of sea turtles, crocodiles and birds),
fishes, frogs (including the invasive and poisonous Marine Toad, or Cane Toad, Rhinella marina), reptiles, birds,
small mammals, molluscs, arthropods (insects, crabs, spiders), carrion, and human food (Bennett 1998; Gaulke,1992). To our knowledge, this is the first record of V. palawanensis predating on a snake.
References:
Bennett, D. (1998). Monitor lizards: natural history, biology & husbandry. Edition Chimaira, Frankfurt am Main. 352
pp.
Gaulke, M. (1992). Taxonomy and biology of Philippine water monitors (Varanus salvator). Philippine Journal ofScience 121(4): 345‐381.
Koch, A., Gaulke, M. and Böhme, W. (2010). Unravelling the underestimated diversity of Philippine water monitor
lizards (Squamata: Varanus salvator complex), with the description of two new species and a new subspecies.
Zootaxa 2446:1‐54.
van Rooijen, J. and Vogel, G. (2012). A revision of the taxonomy of Dendrelaphis caudolineatus (Gray, 1834)(Serpentes: Colubridae). Zootaxa 3272:1‐25.

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