Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 February 2026 | 18(2): 28433–28435
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.10034.18.2.28433-28435
#10034 | Received 02 July 2025 | Final received 19 November 2025 |
Finally accepted 03 January 2026
Hump-nosed Pit Viper Hypnale hypnale
feeding on an Allapalli Skink Eutropis
allapallensis in Karwar, India
Nonita Rana 1 ,
Karthy Shivapushanam
2 , S.J.D. Frank 3 & Govindan Veeraswami Gopi 4
1–4 Wildlife Institute of India, Chandrabani, Dehradun, Uttarakhand 248001, India.
1 nonitarana04@gmail.com, 2 karthysp08@gmail.com,
3 frank.sadrack@gmail.com, 4 gopigv@wii.gov.in
(corresponding author)
Editor: S.R. Ganesh, Kalinga
Foundation, Agumbe, India. Date of
publication: 26
February 2026 (online & print)
Citation: Rana,
N., K. Shivapushanam, S.J.D. Frank & G.V. Gopi (2026). Hump-nosed
Pit Viper Hypnale hypnale
feeding on an Allapalli Skink Eutropis
allapallensis in Karwar, India. Journal of Threatened Taxa 18(2): 28433–28435. https://doi.org/10.11609/jott.10034.18.2.28433-28435
Copyright: © Rana et al. 2026. Creative Commons Attribution 4.0 International License.
JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: Wildlife Institute of India.
Competing interests: The authors declare no competing interests.
Acknowledgements: We gratefully thank the director and dean, Wildlife Institute of India for their support during this study. We extend our sincere thanks to the PCCF (HoFF), PCCF (WL) & CWLW, APCCF (WL)
Karnataka Forest Department for the permission to carry out the field survey. We thank the field director of Kali Tiger
Reserve, deputy conservators
of forests of Karwar and Yellapur Forest Division for the permission and logistical support during the field work. We are thankful to Mr. Bilal, Mr. Parashuram, and Mr. Surya (Karnataka Forest Department) and researchers Mr. Avinash Yadav, Mr. P.K. Tousif, and Mr. Rounak Patra.
Snakes are known to possess
characteristically unique feeding systems (Moon et al. 2019) and documenting
their food habits is vital to understanding their natural history, ecosystem
functions, and evolutionary history (Kalki &
Weiss 2020). Pit-vipers belong to the subfamily Crotalinae
of the Viperidae family and are characterised by
presence of infrared radiation sensing loreal pits, that are located below the
mid-line connecting the eye and nostril (Alencar et
al. 2018). Here, we report our observation on a case of the hunting and feeding
of Hump-nosed Pit Viper based on wild, in situ observation from India.
Field surveys reported here, were
undertaken with due approvals and accompaniment of the Karnataka Forest
Department. The case reported was video-recorded using point and shoot digital
cameras (Nikon P900 & Canon SX 70 HS). The images are given here as
vouchers and the video recording is available on YouTube <https://youtu.be/ZrpJmW3967U>
(Video 1).
Hump-nosed Pit Viper Hypnale hypnale, a
common species known to inhabit evergreen, moist, and dry deciduous forests,
and human modified areas such as plantations in the Western Ghats – Sri Lanka
biodiversity hotspot (Gunawardene et al. 2007). It is
a fairly small-sized (< 0.6 m), terrestrial species, with a flat, triangular
head that is broader than the neck, and back covered with alternating black/
brown specks and large dark triangular spots on each side. It is known to feed
on small mammals like rodents and lizards, geckos, skinks, & frogs (Wall 1906,
1919, 1921; Smith 1943; Das 2002; Whitaker & Captain 2004; Das & DeSilva
2005; Maduwage et al. 2009). Young ones
lure skinks within striking range by enticing them with colourful
tail tips (Henry 1925; Smith 1943; Daniel 2002). Despite being known to science
for over two centuries, and being a common species to the region, there seems
to be a lacuna in the knowledge of its ecology, with only a few ecological
studies available on its fine-scale distribution and abundance (Ganesh et al.
2010; Sawant et al. 2010a,b).
Soon after the first rains in
Karwar forests, Uttara Kannada District, Karnataka, on the night of 23 May
2024, at around 2200 h, we observed a small snake coiled in the leaf litter.
Its pointed snout, distinctive yellow-white line separating the top and sides
of the head, and large triangular spots on the sides helped us identify it as a
Hump-nosed Pit Viper H. hypnale. The snake was
about 25 cm long. It straightened its vertebrae, angled its head out and
started to flick its tongue. The pit viper seemingly sensed its prey, an Allapalli Skink Eutropis
allapallensis (Schmidt, 1926) of 10–12cm
in length, which was foraging on the nearby rocks. The skink was identified by
its dorso-lateral lines that run along the length of
the body, fronto-parietal scale which is united, and
keels on body scales (Image 1) (Deuti et al. 2020).
It was surprising that the diurnal skink was seen moving on leaf litter at
night; but ants were seen close by, suggesting the sleeping skink could have
been disturbed by ants, causing the lizard to move out. The snake, stealthily
observing the movements of the skink, bit it quickly when the skink ventured
too close to the snake. While trying to dodge the attack, the skink slipped and
fell down (approximately 25 cm) and eventually after getting bitten, the
immobile skink was deduced to be dead out of the effects of venom in 40 s. The
viper may have traced its prey using its chemosensory tongue, thermo-sensory
labial pits between the nasal cavity, and its vision to identify the prey that
had slipped down. By this time, the dead skink had already attracted the
attention of the ants on the forest floor. Upon finding the skink, the snake
thoroughly examined it from head to tail by flicking its tongue (approximately
147 times) at the dead skink. This thorough examination continued for over two
minutes when the snake finally moved back to the head of the skink and started
to swallow the skink slowly, using its fangs to hold the prey ventrally between
the jaws. The prey was then pushed into the stomach by the movement of the
jaws. While the snake was about to ingest the hind limbs of the skink, it gave
a jerk reaction in response to the disturbing ant bite on its head. The feeding
(from examining the dead prey to entirely swallowing it) lasted for 6 m 40 s
and was achieved over 44 jaw-walks. The peristaltic movement took over the
swallowing process after the hind limbs were consumed (Image 2). After fully
consuming the skink, the viper continued resting on the rock.
Hump-nosed Pit Vipers have been
observed to feed on skinks, frogs, and agamids in the wild in India (Wall 1906,
1919, 1921; Smith 1943; Daniel 2002; Das 2002; Whitaker & Captain 2004; Das
& DeSilva 2005; Maduwage et al. 2009). Henry
(1925) observed a captive Hypnale sp.
of Sri Lankan origin feeding on another conspecific individual. Wall (1919) reported
the Rock Agama Psammophilus drosalis in the gut of a young one of this snake from Nilgiris, attesting
that diurnal lizard as prey had earlier been reported. Literature
from India, usually reported mice / small mammal in the gut of this
snake (Inger et al. 1984; Wall 1919). Henry (1925), Daniel (2002) specifically
mentioned skinks as being enticed by caudal luring exhibited by baby Hump-nosed
Pit Vipers, another explicit indication associating a diurnal prey, with this
nocturnal species (also see Smith 1943). Maduwage et
al. (2009) recorded skinks and shrews in their gut content in Sri Lankan
populations of H. hypnale.
Though the snake species itself
is common in the Western Ghats, its behaviours are
rarely documented in the wild (Inger et al. 1984; Wall 1919; Daniel 2002; Das
2002; Whitaker & Captain 2004; Ganesh et al. 2010; Sawant et al. 2010a,b). Our feeding observation reported, agrees with
published information on Hypnale as summarised here, and also with the more voluminous body of
scholarship generally on viper feedings. Many terrestrial vipers are known to
rapidly release their prey once bitten (Cundall 2002). Swallowing action of the
pit viper, in engulfing the skink was very similar to what is called pterygoid
walk (Carrasco et al. 2023). To the best of our knowledge, this record is the
first live recorded field observation of a Hump-nosed Pit Viper hunting and
feeding on a skink, in the wild.
For
images - - click here for full PDF
References
Alencar, L.R., M. Martins & H.W.
Greene (2018). Evolutionary
history of vipers. Encyclopedia of Life Sciences - eLS
1–10. https://doi.org/10.1002/9780470015902.a0027455
Carrasco, P.
A., L. Prystupczuk, C. Koch, G.A. González, G.C. Leynaud & F.G. Grazziotin
(2023). Patterns of
morphological variation and ecological correlates in the skull of vipers (Serpentes: Viperidae). Journal of Morphology 284(8):
e21617. https://doi.org/10.1002/jmor.21617
Cundall,
D. (2002). Envenomation strategies, head
form, and feeding ecology in vipers, pp. 149–162. In: Gordon, W., G.W. Schuett, M. Hoggren, M.E. Douglas
& H.W. Greene (eds.) Biology of the Vipers. Eagle Mountain Pub Lc, 580 pp.
Daniel, J.C.
(2002). The Book of
Indian Reptiles and Amphibians. Oxford University Press, Mumbai, 238 pp.
Das, I.
(2002). A
Photographic Guide to Snakes and other Reptiles of India. New Holland Publications,
London, 144 pp.
Das, I. &
A. De Silva (2005). A Photographic Guide to Snakes and other Reptiles of Sri Lanka. New Holland Publications,
London, 144 pp.
Deuti, K., S. Raha,
P. Bag, S. Debnath, A.N. Srikanthan & K. Chandra
(2020). Skinks of
India. Zoological
Survey of India, Kolkata, 383 pp.
Gunawardene, N.R., A.E. Daniels, I.A.U.N. Gunatilleke, C.V.S. Gunatilleke,
P.V. Karunakaran, K.G. Nayak, S. Prasad, P. Puyravaud, B.R. Ramesh, K.A. Subramanian & G. Vasanthy (2007). A brief overview of the Western
Ghats-Sri Lanka biodiversity hotspot. Current Science 93(11):
1567–1572.
Henry, G.M.
(1925). Notes on Ancistrodon hypnale,
the hump-nosed viper. Spolia Zeylanica 13:
257–258.
Inger, R.F.,
H.B. Shaffer, M. Koshy & R. Bakde (1984). A report on a collection of
amphibians and reptiles from the Ponmudi, Kerala,
South India. Journal of the Bombay Natural History Society 81(3):
551–570.
Kalki, Y. & M. Weiss (2020). Understanding the food habits of
the green vine snake (Ahaetulla nasuta):
a crowdsourced approach. Herpetology Notes 13: 835–843.
Maduwage, K., A. Silva, K. Manamendra-Arachchi & R. Pethiyagoda
(2009). A taxonomic
revision of the South Asian hump-nosed pit vipers (Squamata: Viperidae: Hypnale). Zootaxa 2232(1):
1–28. https://doi.org/10.11646/zootaxa.2232.1.1
Moon, B.R.,
D.A. Penning, M. Segall & A. Herrel
(2019). Feeding in
snakes: form, function, and evolution of the feeding system. pp. 527–74.
In: Bels V.& I.Q. Whishaw (eds.). Feeding in
Vertebrates: Evolution, Morphology, Behavior, Biomechanics. Springer,
865pp.
Sawant, N.S.,
T.D. Jadhav & S.K. Shyama (2010a). Distribution and abundance of
pit vipers (Reptilia: Viperidae) along the Western
Ghats of Goa, India. Journal of Threatened Taxa 2(10): 1199–1204. https://doi.org/10.11609/JoTT.o2489.1199-204
Sawant, N.S.,
T.D. Jadhav & S.K. Shyama (2010b). Habitat suitability, threats and
conservation strategies of Hump-nosed Pit Viper Hypnale
hypnale Merrem (Reptilia: Viperidae) found in Western Ghats, Goa, India. Journal
of Threatened Taxa 2(11): 1261–1267. https://doi.org/10.11609/JoTT.o2490.1261-7
Smith, M. A.
(1943). Fauna of
British India, including Ceylon and Burma. Vol- III Serpentes, Taylor and Francis, London, 583
pp.
Wall, F.
(1906). The poisonous
snakes of India and how to recognize them, Part II. Journal of the Bombay
Natural History Society 17: 299–334.
Wall, F.
(1919). Notes on a
collection of snakes made in the Nilgiri hills and
adjacent Wynaad. Journal of the Bombay Natural
History Society 26: 552–584.
Wall, F.
(1921). Ophidia Taprobanica or the Snakes of Ceylon. Colombo Mus. (H.R. Cottle,
govt. printer), Colombo. xxii, 581 pp.
Whitaker, R
& A. Captain (2004). Snakes of India – The Field Guide. Westland Publications &
Draco books, India, 480 pp.