SEAVR 2023: 025‐026
ISSN: 2424‐8525
Date of publication: 10 August 2023
Hosted online by ecologyasia.com

Predation by Philippine Rat Snake Coelognathus philippinus on Common House
Gecko Hemidactylus frenatus on Palawan Island, Philippines
Wilhelm Joshua S. TAN & Emerson Y. SY
wstan@alum.up.edu.ph (Tan), emersonsy@gmail.com (Sy)Observer: Wilhelm Joshua S. Tan.
Photograph by: Wilhelm Joshua S. Tan.
Subjects identified by: Wilhelm Joshua S. Tan, Emerson Y. Sy.
Location: Palawan Island, Barangay Maningning, Puerto Princesa City, Palawan Province, Philippines.
Elevation: 18 metres ASL.
Habitat: Hotel garden adjacent to an empty lot in a highly urbanized area.
Date and time: 15 April 2022, 18:39 hrs.
Identity of subjects:(i) Philippine Rat Snake, Coelognathus philippinus (Reptilia: Squamata (Serpentes): Colubridae).
(ii) Common House Gecko, Hemidactylus frenatus (Reptilia: Squamata (Sauria): Gekkonidae).
Description of record:
A juvenile Philippine Rat Snake was observed
slithering on the ground in the garden of ahotel; a nuptial flight of termites washappening at that time. The termites had
congregated near a light bulb close to theground, and frogs and geckos started to feedon them.
Later, the snake was observed biting theposterior part of the gecko’s body (Fig. 1). The
snake did not release its bite to reorient thegecko head first, but instead started toswallow its prey from the posterior end. It
took approximately seven minutes before thegecko was completely swallowed.
Remarks:
The snake was identified as a juvenile
Coelognathus philippinus based on (i) a seriesof black‐edged white bars on the side of its
body, (ii) a black postocular stripe, and (iii) a
black diagonal stripe starting from theposterior temporal scale (Taylor, 1922;Weinell et al., 2019).
The gecko was identified as Hemidactylus
frenatus based on (i) its size, (ii) its head not
distinctly broader than its body, and (iii) its
greyish‐brown dorsal colour (Brown & Alcala,1978).

Fig. 1.

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W.J.S. Tan

Coelognathus philippinus is an endemic colubrid snake occurring on the islands of Balabac, Bongao, Busuanga,Calauit, Culion, Palawan, Sanga‐Sanga, Sibutu, and Tawi‐Tawi (Sy, 2023). It was once hypothesized that it mainly
fed on birds and small rodents, and not reptiles or amphibians (Taylor, 1922), however a failed attempt to predate
upon a Tokay Gecko (Gekko gecko) was reported some years ago on Palawan Island (Huang et al, 2008).
Hemidactylus frenatus is a gekkonid lizard found throughout the Philippines and commonly observed in disturbed
habitats and inside houses (Taylor, 1922). The Common House Gecko prey could have been feeding on termites
near the ground when the snake attacked it. This is the first report of a successful predation on a gecko by thePhilippine Rat Snake.
References:Brown, W.C. & Alcala, A.C. (1978). Philippine lizards of the family Gekkonidae. Silliman University Press,Dumaguete City, Philippines. v + 146 pp.
Huang, S.C., Chen, M.Y. and Norval, G. (2008). An attack of a tokay gecko (Gekko gecko) on a Palawan ratsnake(Coelognathus philippinus) on Palawan Island, Philippines. Sauria 30 (3): 53‐54.
Sy, E.Y. (Ed.). 2023. Checklist of reptiles of the Philippines, version 2023‐2. Reptile & Amphibian Database
Philippines. Available at:https://www.researchgate.net/publication/362324825_Checklist_of_reptiles_of_the_Philippines
Taylor, E. H. (1922). The lizards of the Philippine Islands. Department of Agriculture and Natural Resources andBureau of Science, Manila. 269 pp. + 22 plates.
Taylor, E. H. (1922). The snakes of the Philippine Islands. Department of Agriculture and Natural Resources andBureau of Science, Manila. 312 pp. + 37 plates.
Weinell, J.L. Hooper, E., Leviton, A.L., Brown, R.M. (2019). Illustrated key to the snakes of the Philippines.
Proceedings of the California Academy of Sciences, series 4, 66(1): 1‐49.

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