Herpetology Notes, volume 7: 447-450 (2014) (published online on 18 August 2014)
Display behaviour in response to a perceived threat by Indian
short-headed kukri snake Oligodon brevicaudus (Günther, 1862)
(Squamata: Colubridae)
Kadaba Shamanna Seshadri
Many snakes have evolved displays in response to
threats and are termed as ‘antipredatory’ behaviour (Mori
and Burghardt 2004). However, the term ‘antipredatory’
behaviour, has been deliberately avoided in this note
because, the behavioural responses may not necessarily
be towards a predator sensu stricto (predator - an animal
that naturally preys on others) but can also be towards
a threat perceived to be ‘merely’ harmful. Here, a new
display in response to a perceived threat (as harmful
and/or predatory) by Oligodon brevicaudus (Indian
short-headed kukri) is described and other displays
reported so far among snakes of the genus Oligodon are
discussed.
There are currently 75 known species in the genus
Oligodon distributed in South and South-East Asia
(David et al., 2012, Uetz 2012). Currently, 21 species
commonly known as ‘kukri’ snakes are reported from
India (David et al., 2011). While most of the species
found in the Western Ghats are docile in habit, there are
a few reports of display behaviour to a perceived threat
when handled or approached by humans (Whitaker
and Captain, 2004). Oligodon brevicaudus (length: 55
cm) is an uncommon, endemic, mostly nocturnal snake
found amongst leaf litter in forests of the Western Ghats
of India (Smith, 1943).
Being relatively uncommon, natural history
information about O. brevicaudus is limited. On 28th
of May 2011 at 1642 h., a single individual of O.
brevicaudus was encountered while it was crossing a
four meter wide tarmac road near Upper Kodayar inside
the Kalakad Mundanthurai Tiger Reserve (KMTR; 8°
31.952’ N and 77° 21.518’ E, 900km2). The road is
located at an elevation of 1500 m and passes through
mid-elevation evergreen forest (Ganesh et al., 1996).
The snake was motionless and lay like a stick when first
sighted on the road (Fig. 1.a). While photographing the
snake, anterior half of the snakes’ body coiled to form an
‘S’ shape (Fig. 1.b). A few more photographs were taken
and on approaching the snake again, the anterior half
of the body was tucked into a highly intense ‘S’ shape
and lifted off the ground. The neck of the snake was
slightly inflated and the ventral scales were iridescent
(Fig.1.b). The posterior half of the body formed a
loose coil. The snake neither twitched its tail, nor did
it attempt to strike. The head was held in mid-air for
about two minutes after which, the snake relaxed and
touched the ground but held the ‘S’ shape in the anterior
of its body (Fig.1.c). The snake was then ushered across
the road using a twig, to avoid it being killed by passing
vehicles. The snake was not handled or collected for
measurements and was identified based on photographs.
The total length of the snake was 394 mm as measured
from photograph using Image J ® software. The ventral
scales of this species are reported to be bright red in
colour (Smith, 1943), however, in the individual that
was observed, there was no red colouration.
Ashoka Trust for Research in Ecology and the Environment,
Royal Enclave, Srirampura, Bangalore- 560064, India
Present address: Department of Biological Sciences, National
University of Singapore 14, Science Drive 4, Singapore
117543
E-mail: [email protected]
Flattening the hood; forming a strike position; ‘S’
shaped coiling of anterior part and lifting it off the
ground and tail twitching are some of the common
response behaviour documented among snakes when
threatened (Rand and Ortleb, 1969). According to
the detailed terminology for identification of such
behaviour and classifying them provided by Mori and
Burghardt (2004), the behaviour of O. brevicaudus can
be classified as two forms of display.
448
Kadaba Shamanna Seshadri
Figure 1. Plate showing display behaviour in response to perceived threat by Oligodon brevicaudus. a-outstretched snake, banterior view showing snake in ‘Strike-Coil’ display and c-snake in dorsal view.
Display behaviour in response to a perceived threat by Oligodon brevicaudus
449
body (Fig 1.b-c) can be categorized as neutral—as it
does not lead to reduction of distance from the threat;
active-in-place—as there is body movement without
locomotion and; threatening—as it is essentially
aimed to deter the threat. Such display has in India so
far only been documented in the snakes of the genus
Coelognanthus (Mehta 2006; V. Deepak and Abhijit
Das, pers. comm.). O. brevicaudus has been observed in
the same study area on two other occasions; one during
dusk and another at night. On both instances, the snake
was found among leaf litter and quickly moved away.
The repertoire of responses to perceived threat among
snakes of the genus Oligodon is varied as documented
from other observations (see Appendix 1). In India,
there are anecdotal observations of O. albocinctus and
O. cyclurus showing displays which are similar to those
described in this note (Fig 2. a, b) and O. dorsalis is
reported to curl and hold up the brightly coloured
underside of the tail (Fig 2.c). There is also a report of
O. cyclurus from Bangkok where the snake displays its
bright red coloured hemipenis against the white coloured
ventral side of tail (Wüster and Cox, 1992). Both these
behaviours appear to be aposematic displays (Davis,
1948) where a bright colour is exhibited suddenly and is
known to deter a threat.
Figure 2. Three species of Oligodon from India displaying
varied responses to perceived threats. a-O. albocinctus;
b-O. cyclurus and c-O. dorsalis.( Image credit: Abhijit Das)
Firstly, the stick-like posture, where the snake lay
outstretched and motionless (Fig 1.a) can be classified as
neutral—as it does not reduce the distance between the
snake and the threat; static—as the snake is immobile
and cryptic—as there is little movement which is likely
to reduce the chance of sighting the snake. Secondly, the
‘S’ shaped coiling and lateral compression of anterior
Response to a perceived threat is an adaptation
especially in young snakes, attributed to their inability
in escaping due to limitations of developing physiology
and it has been suggested that juveniles expressed the
display more than adults (Mehta, 2006). However,
exhibition of such display, even in adults, may be due to
physiological conditions which do not allow for escape
(e.g. recent feeding event, high stress levels, lower
body temperature, breeding phase, moulting etc.). The
functional aspects of such complex display behaviour
can be better understood by carrying out systematically
designed experiments.
Acknowledgements. Field assistant Chian helped to record the
observation. Ashok Captain and V. Deepak identified the snake,
provided comments and encouraged the publication of this note
during and after the 5th Herpetology School conducted by Prof. S.
K. Dutta. Abhijit Das provided images, additional comments and
shared information about behaviour while preparing this note.
Dr. Vogel provided critical inputs on the MS as reviewer. I am
thankful to all of them.
References
Davis, D.D. (1948): Flash Display of Aposematic Colors in
Farancia and Other Snakes. Copeia (3): 208-211
450
Kadaba Shamanna Seshadri
David, P., Das, I., Vogel, G. (2011): On some taxonomic and
nomenclatural problems in Indian species of the genus Oligodon
Fitzinger, 1826 (Squamata: Colubridae). Zootaxa 2799: 1-14.
David, P., Nguyen, T. Q., Nguyen, T. T., Jiang, K., Chen, T., Teynié,
A., Ziegler, T. (2012): A new species of the genus Oligodon
Fitzinger, 1826 (Squamata: Colubridae) from northern Vietnam,
southern China and central Laos. Zootaxa, 3498: 45-62.
Ganesh, T., Ganesan, R., Soubadra, M., Davidar, P., Bawa, K.S.
(1996): Assessment of plant biodiversity at a mid-elevation
evergreen forest of Kalakad Mundanthurai Tiger Reserve,
Western Ghats, India. Current Science 71: 379-392.
Mehta, R.S. (2006): Meal size effects on antipredator behavior of
hatching trinket snakes, Elaphe helena. Ethology 116: 649-656.
Mori, A., Burghardt, G.M. (2004): Thermal effects on the
Antipredator Behaviour of Snakes: a review and proposed
terminology. Herpetological Journal 14:79-87.
Mori, A., Narumi, N., Kardong, K.V. (1992): Unusual Putative
Defensive Behavior in Oligodon formosanus (Serpentes:
Colubridae): Head-Slashing and Tail-Striking. Journal of
Herpetology 26 (2): 213-216.
Rand, A.S., Ortleb, E.P. (1969): Display in the Colubrid Snake
Pseustes poecilonotus shropshirei . Herpetologica 25 (1): 4648.
Smith, M.A. (1943): The Fauna of British India, Ceylon and
Burma, including the whole of the Indo-chinese subregion.
Reptilia and Amphibia. Vol. III, Serpentes. Taylor & Francis,
London, xii + 583.
Uetz, P. (2012): Oligodon. The Reptile Database. Available at:
http://www.reptile-database.org/db-info/SpeciesStat.html. Last
accessed on 8th May 8, 2012.
Whitaker, R., Captain, A. (2004): Snakes of India: The Field Guide.
Draco Books, India.
Wüster, W., Cox, M. J. (1992): Defensive Hemipenis Display in
the Kukri Snake Oligodon cyclurus. Journal of Herpetology 26
(2): 238-241.
Appendix
Classification ofof
responses
to perceived
threat reported
snakes
of the Oligodon
genus.
followsClassification
Mori and
Appendix
1.1.Classification
responses
to perceived
threatamong
reported
among
snakes of
the Classification
genus Oligodon.
follows
Burghardt (2004)
Mori and Burghardt (2004).
Response type
Species
Country
Type of display
O.affinis
India
Biting
Approach
Sideways striking
Neutral
India
Biting
Approach
Locomotive
Escape
Tail curl
Neutral
Active-in-place
Threatening
India
Head ‘S’ shape
Neutral
Active-in-place
Threatening
Bangkok
Tail up and hemipenis
extrusion
Neutral
Active-in-place
India
Tail curl
Neutral
India
Head ‘S’ shape
Neutral
O.dorsalis
India
Ventral scale display
O.formosanus
Taiwan
Head Butting-mouth open
O. albocinctus
O.cyclurus
Change of
Distance
Amount of
Movement
Apparent
function
observation
type
Reference
Locomotive
Escape
anecdotal
Whitaker and Captain, 2004
Active-in-place
Threatening
anecdotal
Whitaker and Captain, 2004 &
Abhijit Das, pers. comm.
Threatening
anecdotal
Wüster and Cox, 1992
Active-in-place
Threatening
anecdotal
Abhijit Das, pers. comm.
Active-in-place
Threatening
anecdotal
Neutral
Active-in-place
Threatening
Anecdotal
Abhijit Das, pers. comm.
Approach
Locomotive
Threatening
Systematic
experiment
Mori et al., 1992
David et al., 2012
Head butting-biting
Approach
Locomotive
Threatening
Tail strike
Neutral
Active-in-place
Threatening
Abhijit Das, pers. comm.
O. nagao
Laos
Tail curl
Neutral
Active-in-place
Threatening
anecdotal
O. octolineatus
Indonesia Tail curl
Neutral
Active-in-place
Threatening
anecdotal
Vogel, G., pers. comm.
O.taeniolatus
India
Body flattening
Neutral
Active-in-place
Threatening
anecdotal
Whitaker and Captain, 2004
Sideways striking
Neutral
Active-in-place
Threatening
O.travancoricus
India
Body flattening
Neutral
Active-in-place
Threatening
anecdotal
Deepak V, pers. comm.
Accepted by Mirco Solé