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INTRODUCTION
South-east Asian landscapes are undergoing rapid
anthropogenic change, posing threats to the region’s
unique biodiversity (Hughes, 2017). To date, most
ecological research in the region has been conducted in
protected areas or in patches of contiguous habitat (Martin
et al., 2012); despite protected areas only representing a
small portion of the total global land area (Juffe-Bignoli
et al., 2014). To better understand how snakes can
persist in human-dominated landscapes, we need a more
comprehensive understanding of their space use.
The Malayan krait (Bungarus candidus) is distributed
across much of south-east Asia and thought to dwell primarily
in forests and plantations (Chan-ard et al., 2015; Wogan et
al., 2012). Two studies have assessed the spatial ecology
and habitat use of B. candidus by radio-tracking. One radio-
tracked a single individual for 22-days (Mohammadi et al.,
2014), the other tracked an individual that only survived 14
days, before being captured and killed in a sh trap within
1 km of our study site (Crane et al., 2016). The objective of
our study was to investigate the ecology of a B. candidus
living within a highly-disturbed landscape, where the risk
for human-snake conict exists. We report our observations
on the movements, habitat preference, and shelter site use
of an individual B. candidus from an agricultural habitat in
Thailand.
METHODS
We captured a B. candidus at approximately 21:30 h on 8
July 2016, as it crossed a dirt path, dividing a Eucalyptus
plantation (Eucalyptus camaldulensis) and a cassava eld,
outside the boundary of the Sakaerat Biosphere Reserve’s
protected Core Area (14.51º N, 101.95º E; WGS84; Fig.
1A). The individual was male, likely a juvenile, weighing
113.5 g and measuring 77.0 cm snout to vent length (SVL)
and 97.6 cm total length. We transported the individual to
our eld laboratory where we anesthetised and surgically
implanted the specimen with a 1.8 g radio transmitter
(Holohil Systems model SD-2, Carp, Ontario, Canada). We
followed the surgical implantation methods described by
Reinert and Cundall (1982), which are believed to not cause
physiological or behavioural changes in snakes (Reinert
& Cundall, 1982). Later that day at dusk, we released the
B. candidus at its site of capture.
To receive the transmitter’s signal and locate the snake,
we used an R410 ATS radio receiver connected to a Telonics
RA-23K VHF antenna. On the days that we did track the
snake, we tracked it for some hours during daylight and at
night-time. In total, we located the snake 21 times during
daylight tracks and 13 times at night. During daylight
tracking (07:00 h to 19:00 h), we used triangulation to
approach the snake, attempting to identify its shelter site
while minimising disturbance. We recorded the location
of the snake using Universal Transverse Mercator (UTM)
WGS 84 projection on a Garmin 64S GPS device. While
at each site, we recorded the habitats the snake used, the
habitats surrounding the snake’s location and attempted to
identify the specic shelter site being used. During night-
time tracking (19:00 h to 07:00 h), we estimated the snake’s
position using wide-arcing triangulations at a minimum
distance of 10 m from the snake to limit disturbance while
it was potentially active. Therefore, we were unable to
accurately identify specic shelter sites or cover used at
night.
Working in R (R Core Team, 2017) with the software
packages adehabitat’ (Calenge, 2006), ‘rgdal’ (Bivand et al.,
2017), and using all observed locations, we calculated the
home range as 100% and 95% minimum convex polygons
(MCP). These were displayed using QGIS (Quantum
GIS Development Team, 2017). We opted to use MCPs
The movements and habitat preferences of a Malayan krait
(Bungarus candidus) in an agrarian landscape
TYLER K. KNIERIM¹, BENJAMIN M. MARSHALL¹, LUCY HAYES², SURACHIT
WAENGSOTHORN³, PONGTHEP SUWANWAREE¹ & COLIN T. STRINE¹*
¹Suranaree University of Technology, Nakhon Ratchasima, Thailand
²Sakaerat Conservation and Snake Education Team, Thailand
³Sakaerat Environmental Research Station, Nakhon Ratchasima, Thailand
*Corresponding author Email: Colin_Strine@sut.ac.th
SHORT NOTE The Herpetological Bulletin 143, 2018: 30-33
ABSTRACT - Little is known about how south-east Asian snakes respond to the conversion of natural areas to human-
dominated land uses. We radio-tracked a Bungarus candidus (Malayan krait) in an agricultural zone of the Sakaerat
Biosphere Reserve in Thailand for 68 days. The snake exhibited nocturnal activity and remained within a 3.23 ha 100%
minimum convex polygon (MCP) home range during this period. Using Duncan’s Index of Preference, we found the snake
preferred less disturbed habitats such as agricultural eld margins (0.90), and to a lesser extent, a Eucalyptus plantation
(0.75).
30 Herpetological Bulletin 143 (2018)
to measure the home range of our snake instead of more
sophisticated estimation methods due to the short tracking
duration of our single individual and our limited number of
locations. Similar studies on related species have also used
MCPs (Mohammadi et al., 2014; Barve et al., 2013; Croak
et al., 2013). This allows comparisons with our data.
Habitat preference was based on daytime shelter site
locations and estimated using the Duncan’s Index which we
log normalised between 0-1 (Duncan, 1983). We dened the
study area used in our habitat analysis as the region within
a 265 m buffer combined with the 95% MCP home range
to eliminate bias from areas unused by the B. candidus. We
derived the width of the buffer from the distance between
the nearest edge of the 95% MCP to the furthest outlining
observation of the snake. The buffer’s width is an estimate of
the longest distance the snake could have moved away from
its 95% MCP core home range area before returning, i.e. a
generous estimation of the area available. We classied 12
habitat types within the study area: roads, highway, human
settlement, cassava eld, maize eld, rice paddy eld,
fallow eld, eucalyptus plantation, mixed fruit orchard,
eld margin, pond, and dry dipterocarp forest (DDF; Fig.
1). The DDF was within the protected Core Zone, all other
habitats were in the reserve’s unprotected transitional and
buffer zones.
RESULTS
We radio-tracked the B. candidus for 68 days (15 July -
21 September 2016) and obtained 34 conrmed locations,
until we were unable to obtain a signal due to transmitter
failure, or less likely, the individual abruptly leaving the
study area. By listening to uctuations in the signal, we
determined that the B. candidus was moving during four of
the 13 night tracks and one of the 21 day tracks. The sole
day time movement occurred at 16:37 h, when the snake
appeared to be moving beneath rocks at the location of its
previously used shelter site. The ambient temperature was
27.1º C and there was 100% cloud cover, following light
rains during the movement observation.
The 100% MCP home range size was 3.23 ha and the
95% was 1.80 ha (Fig. 1). We identied the specic shelter
site used by the B. candidus on eight of the 19 relocations.
The snake sheltered in animal burrows during ve tracks,
termite mounds during two tracks, and beneath rocks during
two tracks. We were unable to identify the specic shelter
site during 11 tracks because of dense vegetation.
The Duncan’s Index revealed a strong preference for
eld margins (0.90), the Eucalyptus plantation (0.75), and
to a lesser extent, a maize eld (0.22). The preference for
maize results from a single shelter site location in which the
Figure 1. The study area and the 12 habitats located within it. Also displayed are the locations that the B. candidus was located as
well as the 95% and 100% MCP areas. The map scale corresponds to the 47N UTM region (m), with each grid square equating to
100 m2.
Herpetological Bulletin 143 (2018) 31
The movements of a Malayan krait (Bungarus candidus) in an agrarian landscape
snake was in a weedy patch of the eld, several meters from
the eld’s densely vegetated margin. All other habitat types
show no preference and absolute avoidance.
All identiable shelter sites used by the B. candidus during
day tracks (animal burrows and termite mounds) were
located on eld margins or within the Eucalyptus plantation.
At one of its shelter sites, the individual sheltered in an
animal burrow complex located within 1 m of the four-
lane highway at the eastern edge of its 100 % MCP home
range. However, we located most shelter sites along a
single margin, approximately 3 m wide, and characterised
by sparse mature trees, unmanaged herbaceous vegetation,
and a dry irrigation ditch running lengthwise through the
site. This margin was primarily bordered by maize elds
on either side.
We did not observe the B. candidus using the DDF, rice
elds, fallow elds, orchards, or human settlements (Fig. 1).
However, several of the locations within the eld margin
brought the snake within 10 m of the nearest household.
Movements during night tracks showed a similar pattern,
suggesting a preference to move along vegetated eld
margins. The snake was either on or within several meters
of a eld margin during tracks in which it was moving. The
snake made use of a narrow eld margin, approximately
1 m in width, to move between the adjoining main eld
margin and the Eucalyptus plantation.
DISCUSSION
Our juvenile male individual had a smaller 100% MCP
home range (3.23 ha) by the end of our 68 day tracking
period than the adult male radio-tracked by Mohammadi
et al. (2014), (12.30 ha) from their 22 day tracking period.
Both snakes were tracked at the apex of the second rainy
season between June-September. Our study also conrms
nocturnal activity in B. candidus which was not reported
by either Mohammadi et al. (2014), nor Crane et al. (2016).
Additionally, our observations highlight the potential
importance of certain landscape features in agricultural
landscapes for B. candidus. We suspect that both
undisturbed raised eld margins and irrigation ditches serve
as essential shelter sites and movement corridors for B.
candidus. Choosai et al. (2009) found that dikes and termite
mounds hosted higher soil macrofaunal biodiversity than
the surrounding elds in north-east Thailand’s agricultural
rice systems. At our study site, agricultural elds undergo
at least two crop rotations per year, subjecting the soil to
frequent disturbances. Eucalyptus plantations, which are
harvested on a 3-5-year cycle, and eld margins, that are
left undisturbed long enough to accumulate animal burrows
and termite mounds, likely provide a stable source of shelter
for B. candidus. Discovering when kraits are active and
whether preference for eld margins and irrigation ditches
continues throughout the year for other individuals will
aid in identifying areas where B. candidus and humans are
most likely to encounter each other.
We suggest future research on B. candidus in agrarian
landscapes to focus on determining activity periods and
assessing microhabitat features, such as the availability of
shelter sites between margins and adjacent anthropogenic
habitats. Identication of specic habitat features will
aid the conservation of B. candidus in anthropogenic
landscapes by providing land managers with explicit
features to maintain. Combatting human-snake conicts
in anthropogenic landscapes is critical to the survival of
snakes (Whitaker & Shine, 2000) and further research into
the movement patterns of this medically important species
may provide insight into how this could be achieved. We
also suggest incorporating more individuals from varying
age classes to investigate whether spatial and activity
patterns differ across age classes.
ACKNOWLEDGEMENTS
We thank Suranaree University of Technology for
facilitating this project. We would like to sincerely thank
the Thailand Institute of Science and Technological
Research (TISTR) and The National Research Council
of Thailand (NRCT) for funding this project. We are also
grateful to the Sakaerat Environmental Research Station for
providing ongoing accommodation and logistical support
for our herpetological research. Our research methods were
carried out with the approval of Suranaree University of
Technology’s animal use and ethics committee.
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The movements of a Malayan krait (Bungarus candidus) in an agrarian landscape
Herpetological Bulletin 143 (2018) 33
