Wolfsnakes, genus Lycodon Fitzinger, 1826, are known to prey upon rodents and frogs (Fritts, 1993), and they may even endanger the survival of bird species (Khamcha and Gale, 2020). However, their biggest impact as a predator is most likely on the broad variety of lizards they consume, including house geckos, skinks, and agamids (Fritts, 1993; Pauwels et al., 2005; Vogel et al., 2009; Zhang and Wang, 2014). Lycodon aulicus (Linnaeus, 1758) in particular is known to feed on common house geckos (Daniel, 2002; Jackson and Fritts, 2004) and, consequently, it may frequently be seen in and around residential buildings where these prey species are most commonly encountered (Shroff, 2016).

Behavioural information about L. aulicus is rather scarce, although a few studies on some populations and its distribution have been carried out (Ganesh and Vogel, 2018; Deshmuk et al., 2020; Ganesh et al., 2020). The species is chiefly nocturnal and known to be partly arboreal, sometimes utilizing tall trees (Harrington et al., 2018), but is most frequently observed in crevices or depressions, under objects, or moving near human settlements. These are generally shy and alert snakes, but they may exhibit more aggressive behaviour than other wolfsnakes (Harris et al., 2010). Several specimens encountered on the campus of the College of Natural Resources, Punakha, Bhutan, coiled up when provoked and tried to escape. Repeated attempts to bite while being handled have been observed by the first author.

Hemidactylus frenatus Duméril & Bibron, 1836 is a common house gecko that occurs throughout most of tropical Asia eastwards into the western Pacific, with introduced populations in parts of Africa, the Americas, and many islands of the Indian and Pacific Oceans (Kraus, 2009). These moderate-sized geckos (maximum snout-to-vent length 65 mm) were identified using identification keys in Smith (1943), Vyas (2005), Giri and Bauer (2008), and Lajmi et al. (2016). In this article, we report the observation of Lycodon aulicus preying upon Hemidactylus frenatus and provide a description of how the attack happened in a sequence of photos with textual commentary.

The second author’s neighbour sought his help to remove a snake found in her ceiling on 11 November 2018 at Burichhu, Tsirang District, Bhutan (27.0823°N, 90.0762°E, elevation 470 m). The atmospheric tempera-ture at the time was ca. 14°C while the room tempera-ture was slightly higher at ca. 17°C (NCHM, 2017). We suspect that the usually nocturnal snake became active during the warm morning and took the opportunity en-ter the warmer, two-storied traditional Bhutanese house to hunt. Both prey availability and warmth could have attracted the snake, which scaled the building’s walls, as also reported by Ganesh et al. (2020). A common wolfsnake (total length ca. 800 mm) was found on one of the ceiling joists, holding a common house gecko in its jaws (Fig. 1). The series of behaviours by the snake associated with predation on the gecko during the fol-lowing several minutes were observed and are reported in detail as follows:

The snake was first encountered strongly biting the central body of the gecko with two coils compressing the anterior part of the body, likely making it difficult for the gecko to inflate its lungs to breathe (Fig. 1). Upon detection of our presence the snake released the gecko (presumably to allow it to react to the disturbance), which dropped to the floor of the home. Unlike normal house gecko behaviour, the seriously

Herpetology Notes, volume 14: 749-753 (2021) (published online on 10 May 2021)

Predation by the wolfsnake Lycodon aulicus (Linnaeus, 1758) on the house gecko Hemidactylus frenatus Duméril & Bibron,

1836 in Tsirang District, Kingdom of Bhutan

Jigme Tshelthrim Wangyal1,*, Pema Khandu2, and Gyeltshen Gyeltshen3

1 University of New England, Armidale, New South Wales 2350, Australia. Present address: Jigme Khesar Strict Nature Reserve, Haa 15001, Bhutan.

2 Wangbama Central School, Genekha, Thimphu, Bhutan.3 Mendrelgang Primary School, Tsirang, Bhutan.* Corresponding author. E-mail: jigmewangyal@gmail.com

© 2021 by Herpetology Notes. Open Access by CC BY-NC-ND 4.0.

Jigme Tshelthrim Wangyal et al.750

injured and stunned gecko moved to some degree, with the snake continuing to observe it. Since the human observers kept their distance, the snake began pursuing the gecko by moving along some furnishings (Fig. 2A) and on the ground (Fig. 2B). Shortly thereafter, once the snake reached the gecko at a safe distance from human observers, it suddenly struck at the gecko’s head (Fig. 2C). Once the snake had captured the lizard by its head, in a position much easier to manipulate, the process of constriction began until the gecko became motionless (after ca. 3 min; Fig. 3A–F). Once the gecko had ceased all movements, the snake took only approximately 30 s to swallow it, assisted by a series of concertina-like muscular waves (peristalsis) along the anterior portion of the body (Fig. 3G–L). The entire predation event lasted approximately 21 min, between 07:30–08:00 h.

Whereas there have been several reports that wolfsnakes eat lizards, and geckos in particular (Fritts, 1993; Daniel, 2002; Jackson and Fritts, 2004) and whereas many people may have observed a wolfsnake

pursuing, subduing, and swallowing prey, to the best of our knowledge there has never been a pictorial report of an encounter between L. aulicus and H. frenatus with complete, pictorial documentation of the encounter. Beyond a simple predator-prey interaction, the detail of our photographs could be informative in terms of functional morphology, as the movement of the snake during swallowing and subsequent peristalsis can be seen. Lastly, with a rather small body of herpetological literature for Bhutan, we hope that publication of this observation may encourage others to make and report on similar encounters from the country.

Acknowledgements. First and foremost, we are grateful to Aaron Bauer (Villanova University, Pennsylvania, USA for providing a pre-peer review, confirming the identification of the gecko, providing technical input, and correcting our text. Our field colleagues who helped us and still support us in our research are also gratefully acknowledged. We are also thankful to Sonam Dorji, Chencho Bidha, and Sonam Tshering for their help in the field, and to Ap Tashi, the homeowner, and Nima Lepcha, the tenant, for granting permission to enter their properties to take photos and rescue the snake.

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Figure 2. After it initially dropped the gecko following the appearance of human observers, the snake pursued it along the fur-nishings (A) and on the ground (B), at 07:48 h. Upon reaching the gecko, the snake re-engaged by launching a sudden strike (C) at 07:49 h.

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Figure 3. The images in this panel show in detail the series of movements on the part of Lycodon aulicus as it subdues, constricts, and immobilizes (A–F) and swallows (G–L) a house gecko. Note the concertina-like peristaltic movement in the later images.

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Accepted by Lukas Hartmann