Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 January 2021 | 13(1): 17455–17469
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.6835.13.1.17455-17469
#6835 | Received 27 October 2020 | Final
received 28 December 2020 | Finally accepted 05 January 2021
Diversity and distribution of
snakes in Trashigang Territorial Forest Division,
eastern Bhutan
Bal Krishna Koirala 1,
Karma Jamtsho 2, Phuntsho
Wangdi 3, Dawa Tshering 4, Rinchen Wangdi 5 , Lam Norbu 6, Sonam Phuntsho 7, Sonam Lhendup
8 & Tshering Nidup
9
1,2,3,4,5,6 Trashigang Forest Division, Department of
Forests and Park Services, Ministry of Agriculture and Forests, Post box: 42001, Trashigang,
Bhutan.
7 Zhemgang Territorial Forest Division,
Department of Forests and Park Services , Ministry of Agriculture and Forests,
Post box 34001, Zhemgang,
Bhutan.
8 Gedu Territorial Forest Division, Department of Forests and Park Services,
Ministry of Agriculture and Forests Post box: 21007, Chhuka,
Bhutan.
9 Department of Environment &
Live Sciences, Sherubtse College, Royal University of
Bhutan, Trashigang, Post box: 42002, Bhutan.
1 bkgelephu@gmail.com
(corresponding author), 2 jamtshokarsel@gmail.com, 3 phunzorong@gmail.com,
4 bongapdawa@gmail.com,
5 pemayounten123@gmail.com,
6 lam.norbu@ymail.com, 7 soms09finso@gmail.com, 8 sonamlhendup20@gmail.com,
9 khangpa@gmail.com
Abstract: This paper presents the results
of a study conducted on the species composition of serpent fauna in Trashigang Territorial Forest Division (TTFD), Bhutan. The survey was conducted from August 2019 to
September 2020. The study aimed to
assess the diversity, conservation threats, and distribution of both venomous
and non-venomous snakes in different habitat types using time constrained
visual encounter survey technique. A
total of 34 species of snakes belonging to five families and 23 genera were
recorded. Of the total observed species,
nine were identified as venomous species.
These include four species of Elapidae, four
species of Viperidae, and one Colubridae. Geographically, snakes occurred throughout
the landscapes, although species composition and their geographical
distribution differed notably amongst various localities. We documented survival threats to local
snakes where deliberate killing and road mortality were found to be the most
common cause of death. The increasing
trend of diversity, species richness, and relative abundance of serpent fauna
was noticed as the radial distance increased from urban residential areas
towards less disturbed landscapes such as rural agricultural land and natural
forests indicating that the habitat mosaic plays an important role in the
structure and composition of the snake community. Considering the limited information currently
available on diversity and geographical distribution of the serpent fauna of
the region, the present study can be considered very significant.
Keywords: Elevation, relative abundance,
serpent fauna, species richness, venomous snakes.
Editor: S.R. Ganesh, Chennai Snake Park,
Chennai, India. Date of publication: 26 January 2021
(online & print)
Citation: Koirala, B.K., K. Jamtsho, P. Wangdi, D. Tshering, R. Wangdi, L. Norbu, S. Phuntsho, S. Lhendup & T. Nidup (2021). Diversity and distribution of
snakes in Trashigang Territorial Forest Division,
eastern Bhutan. Journal of
Threatened Taxa 13(1): 17455–17469. https://doi.org/10.11609/jott.6835.13.1.17455-17469
Copyright: © Koirala et al. 2021. 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: Ruford Small Grants for
Nature Conservation, United Kingdom.
Competing interests: The authors
declare no competing interests.
Author details: Mr. B.K. Koirala is forester by profession,
currently working as Forestry Officer under Department of Forests and Park
Services. His research interests include herpetology and conservation wildlife
biology, and wildlife photography. Mr.
K. Jamtsho is forester by profession and
currently working as Sr. Forester under Department of Forests and Park
Services. His research interests include conservation biology, herpetology and
entomology. Mr. P. Wangdi is forester by profession and working as
Sr. Ranger under Department of Forests and Park Services. His latest passions
include herpetology and conservation biology. Mr. D.
Tshering is forester by profession and working
as Forest Ranger under Department of Forests and Park Services. His latest
passions include herpetology and conservation biology. Mr. R. Wangdi is
forester by profession and working as Sr. Ranger under Department of Forests
and Park Services. His latest passions include herpetology, conservation
biology, and community forestry. Mr. L. Norbu is
forester by profession and working as Forestry Officer under Department of
Forests and Park Services. His latest passions include herpetology,
conservation biology, and working for the conservation of biodiversity. Mr. S. Phuntsho is forester by profession, currently
working as Forestry Officer, under Department of Forests and Park Services. His
research interests include herpetology, wildlife ecology, and GIS modelling. Mr. S. Lhendup
is forester by profession, currently working as Forest Ranger under Department
of Forests and Park Services. His research interests include herpetology,
conservation wildlife biology, and GIS modelling. Mr. T. Nidup is lecturer at Sherubtse College, Royal University of Bhutan. His research
interests include herpetology, entomology, and conservation wildlife biology.
Author contribution: BKK prepared the review design, proof reading and editing. SP
contributed literature review, paper drafting, review, and developed GIS maps.
TN contributed in the literature review collection, paper editing, and
proof reading. All authors contributed in the manuscript revision.
.
Acknowledgements: First of all I would like to
thank Rufford Small Grants for Nature Conservation,
United Kingdom, for funding this conservation Project. I would like to thank to
Ugyen Wangchuk Institute for Conservation and
Environmental Research (UWICER) (Bumthang) for issuance
research permit. My heartfelt thanks go to Mr. Karma Leki
(Chief Forestry Officer, Trashigang Forest Division)
for constructive comments and consistently supporting this project. We
sincerely thank Mr. Phurba Lhendup,
Dr. Om Katel, and Dr. Abhijit Das for their recommendations without which
this work would not have been successful. Likewise, we thank Tandin Wangdi (School Teacher, Trashiyangtse Lower Secondary School), Mr. Kinley Rabgay, Sangay Loday, Ugyen Dechen,
Tshering Dendup, Ugyen Wangchuk, Kezang Penzor, D.B. Rai, for their great contribution in field
work, and all the friends from field who had sincerely contributed and shared
information associated with this conservation project.
INTRODUCTION
Globally,
living snakes (Reptilia: Squamata: Serpentes) as of December 2020 comprise of 3,889 recognized
species belonging to 30 families distributed amongst 531 genera (Uetz et al. 2020).
In southern Asia, India alone is abode to 310 species of snakes belonging
to 16 families (Uetz et al. 2020), and 256 species
distributed amongst 18 families and 73 genera are known to occur in China (Wang
et al. 2020).
Until quite
recently, in Bhutan, there has remained a long gap in the knowledge of serpent
fauna, although many herpetological explorations already had gathered momentum
in neighboring states of India. For example, in the year 1908, Wall (1909)
examined 48 different species of snakes, which include a large part of his own
collection and a few specimens he referred belonged to Darjeeling Museum and
St. Joseph’s College. The type locality
of his collection comes from Darjeeling District, Indian state of West Bengal,
which shares similar topographic complexity and climatic conditions of
Himalayan region. The earliest record of
serpent fauna of Bhutan that is within its political boundary, however, dates
back to mid 1960s when a juvenile specimen of the King Cobra Ophiophagus hannah
(Cantor, 1836) and Buff-striped Keelback Amphiesma
stolatum (Linnaeus, 1758) were recorded in 1966
from Trashigang
and Samdrup
Jongkhar districts, respectively (Biswas 1976). After five years, a few more specimens of
Bhutanese serpents were collected in an expedition by the Natural history
Museum Basel in 1972, where 11 species of snakes belonging to four families
were added as new country records for Bhutan (Bauer & Günther 1992). Since then, Bhutan had remained a
herpetological terra incognita until 2000s, except for a few exclusive studies
by Bustard (1979, 1980a,b) on the status of crocodiles in Bhutan.
Subsequent
herpetological studies in Bhutan include Das & Palden
(2000), Mitra (2009), Wangyal
& Tenzin (2009), Wangyal (2011, 2012, 2013), and Mitra et al. (2012).
These studies conducted at different times and spaces altogether
resulted in up-to-date checklist of 49 species of snakes found in Bhutan. Koirala et al. (2016) reported 17 species of
snakes from Jigme Dorji National Park, western
Bhutan, but without any new country record.
Das et al. (2016) in the Royal Manas national
Park recorded 10 species of snakes, of which Boiga
siamensis Nutaphand,
1971 was reported as new record for Bhutan. Subsequently, Wangyal
& Gurung (2017) summarized all earlier herpetological reports and added new
distribution information that raised the number to 67 species. The recent report of Assamese Cat Snake Boiga quincunciata
(Wall, 1908) by Chaida et al. (2020), and addition of
15 new records by Wangyal et al. (2020) increased the
snake checklist of Bhutan to 85 recognized species.
Snakes are
of great conservation and ecological value (Mullin & Seigel 2009), and
associated population declines has been suggested to have negative implications
for the ecosystems in which snakes play significant roles (Reading et al.
2010). Despite snakes having occupied an
important place in ecology and ethnozoology, venomous snakes in particular,
also command medical attention owing to the propensity of their retaliatory
bites on people and the ensuing medical emergencies. It is important, therefore, to be able to
recognize local venomous snakes. Snakes
are poorly studied in Bhutan and substantial proportion of prior studies on
snakes in Bhutan exclude vital information on type locality, abundance, and
classification based on their medical importance. The baseline information obtained from this
current study would assist relevant authorities, conservationists, and Trashigang Territorial Forest Division (TTFD) to develop
and implement conservation action plan so that species of concern and their
critical habitats are protected. The aim of this study was to document the
diversity, richness, distribution, and also to explore the venomous and
non-venomous snakes in TTFD.
Materials and Methods
Study site
Tashigang Territorial Forest Division (Figure 1) is
located at 27.366 to 27.483 latitude and 91.366 to 92.116 longitude. It
encompasses two districts (Tashigang and Trashiyantse) of eastern Bhutan and it shares its
administrative border with Mongar and Pemagatshel, and towards the north and east it borders with
India. Geographically the division
covers an area of 2447.40km2.
The division spreads over 20 geogs (geog = sub-district) covering over 10,000 households under
two districts. Majority of the people in
these two districts sustain and generate their income through agricultural
practices and depend heavily on natural resources.
Monsoons
occur from May to September and annual rainfall ranges from 1,000mm to
2,000mm. The altitude ranges from
476–4,382m. The tropical and subtropical
zone of the study area experience a hot summer with moderate rainfall, whereas
in the warm temperate and cool temperate zones at higher altitudes, the
climatic conditions are characterized by warm summers and cold winters.
About 79 % and 70% of the total
area of Trashigang and Trashiyangtse
respectively is under forest cover (FRMD 2017).
The corresponding vegetation types across the landscape are
characterized by tropical and sub-tropical forests, warm and cool broadleaved forests,
mixed conifer, and alpine meadows that harbour rich repositories of
biodiversity. Drangmechuu
River, one of the major rivers of Bhutan, with its tributaries spread across
the landscape, flows through mountainous terrains towards south-west, and finally
enters Mongar District. Scrub vegetation, sub-tropical forest belt,
and rock outcrops are prominent geophysical features found along the rivers,
which provides ideal habitats for various snake species.
Methods
Taking into account the rugged
terrain with steep slopes and vast elevation range of the study area, the sites
were surveyed by following time constrained visual encounter method (Heyer et al. 1994; Rödel &
Ernest 2004) along with active search covering all potential habitats in TTFD
from August 2019 to September 2020.
Agricultural lands, open forest, grass lands, roads, and river banks
were searched using the standard visual encounter surveys (VES) method with
three hours’ time constrained (Doan 2003) by three observers in each survey
bout. Areas accessible by roads were
surveyed using a motor vehicle travelling at 10 to 20 km/h. Standardized road
searches were conducted at 18.00–21.00 h thrice a month, covering all potential
areas with the clearest ground visibility.
In total, 120 man-hours were spent to cover the entire study area
searching for nocturnal species.
Locality data along with habitat
parameters were collected for all individual specimens encountered,
irrespective of them being alive or dead.
Wherever possible, the digital photographs were taken for specimens
using Nikon COOLPIX P900 (83x optical zoom) digital camera, elevation and geo-
location of each individual sighted was recorded using a GPS (global
positioning system) Garmin eTrex. Species were identified using standard field
guide books Daniel (2002), Vasudevan & Sondhi
(2010), Ahmed et al. (2009), Whitaker & Captain (2004), and Das (2002,
2015).
RESULTS
Diversity
In total, 96-day field trips or
1,152 man-hours were spent searching for snakes in TTFD, of which 120 man-hours
covering a total distance of 400km were dedicated to standardized road survey
at night searching for nocturnal snakes.
A total of 34 species of snakes
belonging to five families and 23 genera were recorded in different habitats
and around the human habitations of TTFD (Table 1). The observations include eight singletons
(species with only one observation) and five doubletons (species with two
observations). Recorded families were Colubridae, Elapidae, Viperidae, Pareidae, and Typhlopidae. During the present survey, three species of
snakes could not be confirmed at species level, hence conferred to closely
related species (e.g., Amphiesma sp., Trachischium cf. fuscum,
and Trimeresurus cf. salazar).
A total of 217 sightings were
obtained during the entire study period.
The family Colubridae was found to be the most
diverse in terms of species richness, generic richness and abundance. The family Colubridae
accounted for 14 genera and 24 species, followed by the Elapidae
(four genera, four species). The third
most speciose family was Viperidae (three genera, four species), and Paeridae & Typhlopidae were
found to be the least diverse families, each being represented by one genus
with a single species (Figure 2).
Of the total observed species,
nine were identified as venomous. These
include four species of elapids, viz., King Cobra Ophiophagus
hannah (Cantor, 1836), Monocled
Cobra Naja kaouthia
(Lesson, 1831), MacClelland’s Coral Snake Sinomicrurus macclellandi
(Reinhardt, 1844), and Greater Black Krait Bungarus
niger (Wall, 1908), four species of viperids,
viz., Jerdon’s Pitviper Protobothrops jerdonii
(Günther, 1875), Kaulbacki’s Pitviper
Protobothrops kaulbacki
(Smith, 1940), Mountain Pitviper Ovophis
monticola (Günther, 1864), and Salazar’s Pitviper Trimeresurus cf.
salazar Mirza, Bhosale, Phansalkar,
Sawant, Gowande & Patel, 2020, one species of
dangerously venomous rear-fanged colubrid, viz., Red-necked Keelback Rhabdophis subminiatus (Schlegel,
1837).
Relative abundance
A total of 217 sightings were
recorded during the entire study period.
Relative abundance data indicated that snakes belonging to Colubridae were found to be the most common (n=143,
65.89%), followed by Elapidae (n=53, 24.42%), Viperide (n=16, 7.37%), Pareidae
(n=3, 1.38%), and species belonging to Typhlopidae
were observed as least common (n=2, 0.92%) of the total individuals recorded
(Figure 3). Colubrids
were most dominant in the data because of their high richness and comprised
70.58% of total species recorded.
At species level, the abundance
of snakes varied from 1–24 sightings.
Analyses of species composition and relative abundance revealed that N.
kaouthia (Image 1) was the most frequently
encountered species with 24 sightings and made up 11.05% of the snake community
at Trashigang Forest Division. This was followed by O. hannah (Image 2) with 18 sightings contributing
8.29%, Orthriophis cantoris (Boulenger, 1894) and Pseudoxenodon
macrops (Blyth, 1855) (Image 3) with 14
individuals contributing 6.45% each.
Other 17 commonly encountered species, altogether contributed
59.44%. Five doubletons species together
accounted 4.60%, and remaining eight singletons species, viz., Amphiesma sp., Hebius
parallelum (Boulenger,
1890), Dendrelaphis proarchos
(Wall, 1909), Dendrelaphis cyanochloris
(Wall, 1921), Lycodon septentrionalis
(Günther,1875), Lycodon gammiei
(Blanford, 1878), Ptyas
mucosa (Linnaeus, 1758), and Rhabdophis
subminiatus were least common and collectively
contributed to only 3.68% of the total abundance.
Distribution
Geographically, snakes in study
area occurred throughout the landscape up to 2,300m (Figure 4), although
species composition and their geographical distribution differed notably
amongst various localities (Figure 5).
The study showed that snakes are sparsely distributed towards the higher
elevation, however majority of them demonstrated uniform distribution pattern
along the river valleys particularly below 1,800m. Among the observed snakes,
species such as O. hannah, S. collaris, N. kaouthia,
O. albocinctus (Image 4), O.
monticola, O. porphyraceus, A.
prasina, P. korros
(Image 5), Boiga ochracea
(Image 6), O. cantoris, and T. tenuiceps
were most widely sighted species across the landscape. Whereas, P. kaulbacki,
Trimeresurus cf. salazar,
A. platyceps, Amphiesma
sp., D. cyanochloris, L. gammiei, Trachischium
cf. fuscum (Image 7), and P.
mucosa were recorded from a few specific localities. Range extension of these species, however, is
not limited to present study locations because the type locality of observed
species, shares similar climatic conditions and bio-geographic elements of
eastern Himalayan locations from where most of the snakes in Bhutan have been
reported.
The geo-physical features and
biogeographic elements within the study area and adjoining landscapes are
mainly forged by two major rivers. These
rivers originate from China and flow through mountainous landscape of eastern
Bhutan before entering the Indian state of Assam; Kurichu
River flows through mountainous terrains of adjoining district of Mongar and meets with the Drangmechu
River about 70km south-west of Trashigang. These two major rivers, with their
tributaries create continuous stretch of biologically rich valleys across the
landscape of eastern Bhutan. These
climatically suitable warm valleys with habitat mosaic presumably support more
ophidian faunal diversity and distribution than already recorded in the present
study.
Threats and conservation issues
Among the total sightings (n=140
specimens; 64.51%) were recorded live and (n=77 specimens; 35.48%) were found
dead. After close examination of all
dead specimens, cause of deaths was estimated to be of anthropogenic origin,
including road mortality and direct persecution. Virtually all kinds of snakes were killed
instantly in first encounter, the most frequently killed species were B.
niger, N. kaouthia,
O. hannah, A. prasina (Image 8), C. radiatus,
P. korros, O. cantoris,
and O. monticola. We observed a few cases of human-caused death
of forest dwelling species, although most of the dead snakes were recorded from
rural agricultural lands and in close proximity to urban residential
areas. Species such as O. hannah, P. korros,
C. radiatus, and O. cantoris were found to be most
vulnerable to human killing as 33–60 % of total sightings encountered were
recorded dead, wherein the cause of mortality was identified to be direct human
persecution.
Discussion
Straddling the two major
Indo-Malayan and Palaearctic biogeographic realms, Bhutan, a part of eastern
Himalaya, is one of the biologically richest areas on earth and encompasses an
incredible wealth of biodiversity. TTFD
is one of the important conservation areas in eastern Himalaya which
encompasses a wide range of habitats from sub-tropical to alpine ecosystems of
Bhutan. Considering the limited
information currently available on diversity, distribution and natural history
of the serpent fauna of the region, the present study can be considered very
significant.
As per IUCN Red List Category, 10
species belong to LC (Least Concern) category, two species DD (Data Deficient),
one species VU (Vulnerable), 18 are not assessed, and three species could not be identified at species
level thus its status is excluded. This
indicates that for about 59% of the species there are not sufficient data
available for evaluating their conservation status in this region.
Serpent fauna of Bhutan as of
April 2020 was represented by 70 recognized species (Chaida
et al.2020), and new records of 15 additional species by Wangyal
et al. (2020) elevate the number of snakes species in Bhutan to 85. The number of snake species found in this
research represented 40.47% of all snake species found in Bhutan. Of the eight families and 33 genera of snake
fauna found in the country, five families and 23 genera were recorded in
TTFD. This implies that TTFD is an
important repository for serpent fauna conservation.
Three species of venomous snakes,
viz., O. hannah, O. monticola
(Image 9), and N. kaouthia, were previously
reported by Biswas (1976) and Mitra (2009) from Trashigang
District, which are also recorded in present study. Nonetheless, our records of five more species
of venomous snakes, viz., P. jerdonii (Image
10), P. kaulbacki (Image 11), Trimeresurus cf. salazar
(Image 12), B. niger (Image 13), and S. macclellandi (Image 14) are recorded for the first time
from TTFD. This population was
previously called as T. albolabris till the
species Trimeresurus salazar
got described (Mirza et al. 2020). Discovery
of higher diversity of venomous snakes which is more than (52%) of total
venomous snakes found in Bhutan warrants better medical attention to this
problem.
Our records of 10 additional
species, viz., Pareas monticola
(Cantor, 1839) (Image 15) Trachischium cf. fuscum (Blyth, 1854), P. kaulbacki,
D. cyanochloris, D. proarchos (see Vogel & van Rooijen 2007, 2011), (Image 16), P. mucosa, R.
subminiatus, L. gammiei,
Indotyphlops braminus (Daudin, 1803), and A. platyceps
are the first records of these species for TTFD. Although Mitra
(2009) mentioned two species of Kukri snakes viz., Oligodon
juglandifer (Wall, 1909) and Oligodon
cyclurus (Cantor, 1939), and Boiga
multifasciata (Blyth, 1861) (Image 17) from present area but we did not detect
former two species in this present study but later were found around 78km away
from the previously recorded locality.
Our records of Trachischium tenuiceps (Blyth, 1854) (Image 18), L. septentrionalis, Oreocryptophis
porphyraceus (Cantor, 1839) (Image 19), and Boiga ochracea
(Theobald, 1868) extends the distribution range of these species by 74km from
the previously recorded locality, Kanglung, Trashigang District (Mitra 2009)
to Yangtse, Trashigangtse District in the north. The occurrence of L. gammiei and D. cyanochloris
in Bhutan (Wangyal, 2014) was reported without
locality data. We, however, confirmed
the presence of these two species from TTFD based on dead specimens recorded
from Khaling and Bartsham,
respectively. We could not find Pope’s Pitviper Trimeresurus popeiorum (Smith, 1937) in TTFD. Our record of T. popeiorum
(Image 20) from adjoining locality (Pemagatshel
District), however, suggests that the species probably also occurs in TTFD.
Information on habitats used by
snakes can be an important tool for conservation efforts (Seigel & Mullin
2009). Our study revealed that snakes in
Bhutan use a wide variety of habitats which forest habitat, grasslands, rural agricultural
farm land, and urban residential areas.
Modifications in each landscape showed different levels of
disturbance. The study showed that as
the distance from residential area increased, the abundance, richness, and
diversity of snakes also increased. This
result concurred with similar phenomenon reported by Janiawati
et al. (2015). The monotonic increase in
richness and diversity of snakes with the increase in redial distance from
urban residential area could be due to majority of snakes responding to
disturbance levels, availability of resources, vegetation cover, varied
habitats, and increased space. A more
varied habitat can accommodate more species because more resources can be
utilized (Janiawati et al. 2015). Reptiles use vegetation cover to protect
themselves from environmental changes or predators (Botejue
& Wattavidanage 2012). Highly modified landscapes contain few
remnant vegetation (McIntyre & Hobbs 1999), thus provide limited
resources. In contrary, increased
abundance of some of the Elapid species, viz., N. kaouthia
and B. niger in urban residential area
could be due to availability of preferred microhabitat and their ability to
withstand high degree of environmental changes resulted from landscape
modifications.
Overall, these data suggest that
species richness and diversity in of TTFD is relatively high, and that small
geographic localities can sustain a large number and diverse group of snakes
species. We suggest more comprehensive
surveys and intensive research, particularly in ecologically vulnerable areas
containing high biodiversity to facilitate snake monitoring efforts, assess
threats to snakes, foresee potential threats to vulnerable snake species (e.g.,
O. hannah), better understand the
distribution and ecology of medically significant species of snakes, rare and data-deficient species, and to
ultimately formulate effective conservation strategy for conservation of
serpent fauna of eastern Bhutan.
Human-caused mortality of snakes
was the most severe among the threats that we observed. Although there have been no records of live
snakes or their parts being traded in Bhutan, there are sufficient evidences
that they are killed indiscriminately because of fear of snakebite. People in Bhutan have very little knowledge about
snakes; as a result, many harmless species get victimized mainly due to belief
that all snakes are venomous. Road
mortality and direct human persecution are primary threats to snakes in the
region. Frequent forest fires may also
contribute to overall snake mortality in TTFD.
The recorded evidences of high mortality (35.48%) within short span of
time due to human persecution highlights how precarious human-dominated
landscapes are for snakes.
Historically, due to the rugged
terrains, cold climatic condition, and largely inaccessible landscape,
biological diversity of Eastern Himalaya remained largely unexplored. Tremendous effort, however, had been made in
recent decades and frequent addition of new records in the eastern Himalayas
demonstrates a serious need for further exploration in the region. Our results are based on surveys constrained
by time, and presumably do not represent actual diversity as there are still
some potential areas which remained unexplored.
Majority of conservation efforts in Bhutan are focused on conservation
of biodiversity in protected areas, however, many areas outside protected areas
are biologically rich and thus offers great opportunities to conserve at least
a portion of its diversity. We hope that
our findings may serve as a foundation for further studies in this and other
regions of Bhutan. Furthermore, we also
emphasize on more holistic, education-focused conservation strategy combined
with ecological research to address the snake-human negative interaction in the
region.
Table 1. List of snake species
documented in TTFD during August 2019–September 2020.
|
Families |
Scientific name |
Common name |
IUCN status |
|
Elapidae |
Bungarus niger |
Greater Black Krait |
Not assessed |
|
Naja kaouthia |
Monocled Cobra |
Least Concern |
|
|
Ophiphagus hannah |
King Cobra |
Vulnerable |
|
|
Sinomicrurus macclellandi |
Macclellandi’s Coral Snake |
Not assessed |
|
|
Viperidae |
Ovophis monticola |
Mountain Pit Viper |
Least Concern |
|
Protobothrops jerdonii |
Jerdon’s Pit Viper |
Least Concern |
|
|
Protobothrops kaulbacki |
Kaulback's Lance-headed Pit
Viper |
Data Deficient |
|
|
Trimeresurus cf. salazar |
|
|
|
|
Colubridae |
Ahaetulla prasina |
Short-nosed Vine Snake |
Least Concern |
|
Amphiesma sp. |
|
|
|
|
Amphiesma platyceps |
Himalayan Keelback |
Not assessed |
|
|
Boiga ochracea |
Tawny Cat Snake |
Not assessed |
|
|
Boiga multifasciata |
Many-banded Cat Snake |
Data Deficient |
|
|
Coelognathus radiatus |
Copper-headed Trinket |
Least Concern |
|
|
Dendrelaphis proarchos |
Assam Bronzeback |
Not assessed |
|
|
Dendrelaphis cyanochloris |
Wall's Bronzeback |
Least Concern |
|
|
Hebius parallelum |
Yunnan Keelback |
Not assessed |
|
|
Lycodon septentrionalis |
Large-toothed Wolf Snake |
Not assessed |
|
|
Lycodon gammiei |
Gammiei’s Wolf Snake |
Not assessed |
|
|
Oligodon albocinctus |
White-barred Kukri Snake |
Not assessed |
|
|
Oligodon taeniolatus |
Streaked Kukri Snake |
Least Concern |
|
|
Oreocryptophis porphyraceus |
Black-banded Trinket |
Not assessed |
|
|
Orthriophis cantoris |
Eastern Trinket |
Not assessed |
|
|
Pseudoxenodon macrops |
Large-eye False Cobra |
Least Concern |
|
|
Ptyas korros |
Indo-Chinese Rat Snake |
Not assessed |
|
|
Ptyas mocosa |
Indian Rat Snake |
Not assessed |
|
|
Ptyas nigromarginata |
Green Rat Snake |
Not assessed |
|
|
Rhadobphis himalayanus |
Orange-collared Keelback |
Not assessed |
|
|
Rhadobphis subminiatus |
Red-necked Keelback |
Least Concern |
|
|
Sibynophis collaris |
Collared Black Headed Snake |
Least Concern |
|
|
Trachischium tenuiceps |
Oriental Worm-eating Snake |
Not assessed |
|
|
Trachischium cf. fuscum |
|
|
|
|
Pareidae |
Pareas monticola |
Slug-eating Snake |
Not assessed |
|
Typhlopidae |
Indotyphlops braminus |
Common Blind Snake |
Not assessed |
Table 2. Locality records of
Snakes in Trashigang Forest Division. Localities data
indicate geogs (geog =
sub-district) within Trashigang Forest Division where
species were sighted.
|
Species name |
Localities |
Latitude (0N) |
Longitude (0E) |
Altitude (m) |
|
Ophiophugus hannah |
Thrimshing |
27.111 |
91.590 |
650–2,057 |
|
Barsam |
27.373 |
91.587 |
||
|
Radi |
27.363 |
91.723 |
||
|
Samkhar |
27.325 |
91.558 |
||
|
Kanglung |
27.283 |
91.522 |
||
|
Lumang |
27.138 |
91.495 |
||
|
Yangte |
27.612 |
91.499 |
||
|
Naja kaouthia |
Samkhar |
27.331 |
91.552 |
670–1,471 |
|
Shongphu |
27.359 |
91.644 |
||
|
Toetsho |
27.481 |
91.605 |
||
|
Khamdang |
27.436 |
91.574 |
||
|
Thrimshing |
27.122 |
91.609 |
||
|
Udzorong |
27.258 |
91.451 |
||
|
Bugarus niger |
Lumang |
27.147 |
91.501 |
700–1,400 |
|
Shongphu |
27.358 |
91.683 |
||
|
Khamdang |
27.455 |
91.576 |
||
|
Samkhar |
27.330 |
91.556 |
||
|
Sinomicrurus macclellandi |
Lumang |
27.122 |
91.548 |
1,300–1,400 |
|
Thrimshing |
27.127 |
91.634 |
||
|
Ovophis monticola |
Khaling |
27.209 |
91.596 |
1,700–2,300 |
|
Yangtse |
27.595 |
91.493 |
||
|
Udzorong |
27.235 |
91.444 |
||
|
Phogmey |
27.443 |
91.798 |
||
|
Kanglung |
27.282 |
91.521 |
||
|
Protobothrops kaulbacki |
Kangpara |
27.123 |
91.699 |
1,642 |
|
Protobothrops jerdonii |
Khaling |
27.205 |
91.703 |
1,800–2,000 |
|
Yangtse |
27.634 |
91.490 |
||
|
Trimeresurus cf. salazar |
Lumang |
27.138 |
91.496 |
995 |
|
Ahaetulla prasina |
Samkhar |
27.335 |
91.555 |
700–1,300 |
|
Shongphu |
27.360 |
91.665 |
||
|
Khamdang |
27.436 |
91.574 |
||
|
Udzorong |
27.258 |
91.451 |
||
|
Amphiesma platyceps |
Yangtse |
27.565 |
91.506 |
1,805 |
|
Amphiesma sp. |
Yangtse |
27.570 |
91.489 |
1,800 |
|
Boiga ochracea |
Jamkhar |
27.397 |
91.540 |
800–1,834 |
|
Yangyeer |
27.366 |
91.533 |
||
|
Samkhar |
27.332 |
91.541 |
||
|
Lumang |
27.138 |
91.495 |
||
|
Yangtse |
27.603 |
91.493 |
||
|
Boiga multifasciata |
Yangtse |
27.612 |
91.499 |
1,400–1,821 |
|
Kanglung |
27.274 |
91.541 |
||
|
Coelognathus radiatus |
Samkhar |
27.333 |
91.556 |
800–1,300 |
|
Udzorong |
27.258 |
91.451 |
||
|
Shongphu |
27.360 |
91.665 |
||
|
Dendrelaphis proarchus |
Samkhar |
27.337 |
91.559 |
1,000–1,200 |
|
Udzorong |
27.244 |
91.445 |
||
|
Dendrelaphis cyanochloris |
Bartsham |
27.361 |
91.576 |
1,400 |
|
Hebius parallelum |
Yangtse |
27.633 |
91.489 |
1,890 |
|
Lycodon septentrionalis |
Kanglung |
27.273 |
91.537 |
1,700–1,900 |
|
Yangtse |
27.585 |
91.494 |
||
|
Lycodon gammiei |
Khaling |
27.585 |
91.494 |
2,100 |
|
Oligodon albocinctus |
Kangpara |
27.207 |
91.597 |
700–1,821 |
|
Kanglung |
27.139 |
91.751 |
||
|
Khamgang |
27.273 |
91.537 |
||
|
Samkhar |
27.436 |
91.574 |
||
|
Yangtse |
27.351 |
91.593 |
||
|
Oligodon taeniolatus |
Khamdang |
27.576 |
91.501 |
750–1,800 |
|
Yangtse |
27.436 |
91.574 |
||
|
Yangtse |
27.612 |
91.499 |
||
|
Oreocryptophis porphyraceus |
Kanglung |
27.612 |
91.499 |
1,200–1,800 |
|
Thrishing |
27.282 |
91.522 |
||
|
Udzorong |
27.131 |
91.635 |
||
|
Yangtse |
27.259 |
91.453 |
||
|
Lumang |
27.576 |
91.501 |
||
|
Orthriophis cantoris |
Lumang |
27.138 |
91.576 |
1,300–2,205 |
|
Phogmey |
27.138 |
91.576 |
||
|
Samkhar |
27.443 |
91.798 |
||
|
Udzorong |
27.329 |
91.568 |
||
|
Pseudoxenodon macrops |
Khaling |
27.244 |
91.445 |
1,800–2,100 |
|
Kanglung |
27.209 |
91.596 |
||
|
Lumang |
27.272 |
91.530 |
||
|
Ptyas korros |
Udzorong |
27.138 |
91.572 |
750–1,800 |
|
Samkhar |
27.258 |
91.451 |
||
|
Kanglung |
27.314 |
91.537 |
||
|
Shongphu |
27.283 |
91.522 |
||
|
Ptyas mocosa |
Udzorong |
27.359 |
91.665 |
2,000 |
|
Ptyas nigromarginata |
Kanglung |
27.235 |
91.444 |
1,400–2,300 |
|
Yangtse |
27.287 |
91.525 |
||
|
Khaling |
27.577 |
91.501 |
||
|
Lumang |
27.211 |
91.585 |
||
|
Rhadobphis himalayanus |
Lumang |
27.121 |
91.529 |
1,500–1,700 |
|
Kanglung |
27.126 |
91.618 |
||
|
Rhadobphis subminiatus |
Thrimshing |
27.278 |
91.527 |
1,600 |
|
Sibynophis collaris |
Thrimshing |
27.129 |
91.630 |
650–1,870 |
|
Samkhar |
27.128 |
91.631 |
||
|
Kanglung |
27.312 |
91.538 |
||
|
Yangtse |
27.283 |
91.522 |
||
|
Trachischium tenuiceps |
Khaling |
27.602 |
91.503 |
900–2,300 |
|
Shongphu |
27.209 |
91.596 |
||
|
Yangtse |
27.356 |
91.651 |
||
|
Kanglung |
27.576 |
91.501 |
||
|
Trachischium cf. fuscum |
Lumang |
27.283 |
91.522 |
1,800–2,300 |
|
Pareas monticola |
Samkhar |
27.131 |
91.567 |
1,200–1,400 |
|
Lumang |
27.331 |
91.611 |
||
|
Indotyphlops braminus |
Samkhar |
27.100 |
91.466 |
700–900 |
For
figures & images - - click here
References
Ahmed, M.F.,
A. Das & S.K. Dutta (2009). Amphibians and Reptiles of
Northeast India: A
Photographic Guide. Guwahati, Assam, India, Aaranyak,
169pp.
Biswas, S. (1976). Reptiles from Bhutan with
description of a new species of Calotes Rafinesque.
Journal of the Bombay Natural History Society 72: 774–777.
Bustard, H.R.
(1979). Bhutan:
Crocodile Conservation Commercial Fanning. FAO:DP/BHU/78/003. FAO, Rome, 9pp.
Bustard, H.R.
(1980a). Status of
the Gharial (Gavialis gangeticus
Gmelin) in Bhutan. Journal of the Bombay
Natural History Society 77: 150.
Bustard, H.R.
(1980b). Extinction
of the gharial (Gavialis gangeticus)
in Bhutan. British Journal of
Herpetological 6: 68.
Bauer, A.M.
& R. Günther (1992). A preliminary report on the reptile fauna of the Kingdom of Bhutan with
the description of a new species of scincid lizard. Asian
Herpetological Research 4: 23–36.
Botejue, W.M.S. & J. Wattavidanage ( 2012). Herpetofaunal
diversity and distribution in Kalugala proposed
forest reserve, western province of Sri Lanka. Amphibian and Reptile
Conservation 5(2): 65–80.
Chaida, L., A. Das, U. Tshering & D. Wangdi (2020). Assamese Cat Snake Boiga quincunciata
(Wall, 1908) (Reptilia: Squamata: Colubridae)
- new country record for Bhutan. Journal of Threatened Taxa 12(5):
15664–15667. https://doi.org/10.11609/jott.5597.12.5.15664-15667
Daniel, J.C.
(2002). The Book
of Indian Reptiles and Amphibians. Bombay Natural History Society, Oxford
University Press, Mumbai, 238pp.
Das, A., P.
Sharma, H. Surendran, A. Nath, S. Ghosh, D. Dutta, J.
Mondol & Y. Wangdi
(2016). Additions to
the herpetofauna of Royal Manas National Park, with
six country records. Herpetology Notes 9: 261–278.
Das, I.
(2002). Photographic
Guide to Snakes and Other Reptiles of India. New Holland Publishers (UK)
Ltd., 144pp.
Das, I. (2015). A Field Guide
to the Reptiles of South-East Asia: Myanmar, Thailand, Laos, Cambodia,
Vietnam, Peninsular Malaysia, Singapore, Sumatra, Borneo, Java, Bali. Bloomsbury
Natural History, New Holland, 376pp.
Das, I. &
J. Palden (2000). A herpetological collection from
Bhutan, with new country records. Herpetogical
Review 31: 25–258.
Doan, T.M.
(2003). Which
methods are most effective for surveying rain forest herpetofauna? Journal of
Herpetology 37: 72–81.
FRMD (2017). Land
Use and Land Cover of Bhutan 2016, Maps and Statistics. Forest Resources
and Management Division. Department of Forests and Park Services, Ministry
of Agriculture and Forests, Thimphu Bhutan, 21pp.
Heyer, W.R., M.A. Donnelly, R.W. Mcdiarmid, L.C. Hayek & M.S. Foster (1994). Measuring and Monitoring
Biological Diversity: Standard Methods for Amphibians. Smithsonian
Institution Press, Washington.
Janiawati, I.A.A., M.D. Kusrini & A. Mardiastuti
(2015). Structure
and composition of reptile communities in human modified landscape in Gianyar Regency, Bali. Hayati
Journal of Biosciences 23: 85–91. https://doi.org/10.1016/j.hjb.2016.06.006
Koirala,
B.K., D.B. Gurung, P. Lhendup & S. Phuntsho (2016). Species diversity and spatial
distribution of snakes in Jigme Dorji National Park
and adjoining areas, western Bhutan. Journal of Threatened Taxa 8(12):
9461–9466. https://doi.org/10.11609/jott.2617.8.12.9461-9466
McIntyre, S.
& R. Hobbs (1999). A framework for conceptualizing human effects on landscapes and its
relevance to management and research models. Conservation Biology 13:
1282e92.
Mirza, Z.A.,
H. S. Bhosale, P.U. Phansalkar, M. Sawant, G.G. Gowande & H. Patel (2020). A new species of green pit viper
of the genus Trimeresurus Lacépède, 1804 (Reptilia, Serpentes, Viperidae) from western Arunachal Pradesh,
India. Zoosystematics and Evolution
96(1): 123–138. https://doi.org.10.3897/zse.96.48431
Mitra
A. (2009). New records of snakes from District Trashigang.
The Bioscan 4(1): 15–20.
Mitra, A., T. Nidup, Chaten, K.P. Bastola & Sonam
(2012). Snake
diversity at Sherubtse Natural Reserve Study Area
(SNRSA), Khaling
Kharungla Forest Management Unit (KKFMU). The
Research Journal of Sherubtse College 12(1): 1–5.
Mullin, S.J.
& R.A. Seigel (2009). Snakes: ecology and conservation. Cornell University Press,
Ithaca, New York, USA, 365pp.
Reading,
C.J., L.M. Luiselli, G.C. Akani, X. Bonnet, G. Amori, J.M. Ballouard, E. Filippi, G. Naulleau, D. Pearson
& L. Rugiero (2010). Are snake populations in
widespread decline? Biology Letters 23: 777–780.
Rödel, M.O. & R. Ernst (2004). Measuring and monitoring
amphibian diversity in tropical forests. An evaluation of methods with
recommendations for standardization. Ecotropica
10: 1–14.
Seigel, R.A.
& S.J. Mullin (2009). Snake conservation, present and
future, pp. 281–290. In: Mullin, S.J. & R.A. Seigel (eds.). Snakes,
Ecology and Conservation. Cornell University Press, xiii+362pp.
Uetz, P., P. Freed & J. Hošek (eds.) (2020). The Reptile Database, accessed
on December 31, available at http://www.reptile-database.org.
Vasudevan, K.
& S. Sondhi (2010). Amphibians and Reptiles of Uttarakhand,
India. Wildlife
Institute of India, Chandrabani 18, Dehradun,
Uttarakhand, India, 94pp.
Vogel, G. & J. van Rooijen (2007). A new species of Dendrelaphis (Serpentes: Colubridae) from Southeast Asia. Zootaxa
1394: 25–45.
Vogel, G. & J. van Rooijen (2011). Contributions to a Review of the Dendrelaphis pictus
(Gmelin, 1789) Complex (Serpentes:
Colubridae) — 3. The Indian Forms, with the
Description of a New Species from the Western Ghats. Journal of Herpetology
45(1): 100–110.
Wall, F. (1909). Notes on snakes from the neighbourhood of Darjeeling. Journal of
the Bombay Natural History Society 19: 337–357.
Wang, K., J.
Ren, H. Chen, Z. Lyu, X. Guo, K. Jiang, J. Chen, J.
Li, P. Guo, Y. Wang & J. Che (2020). The updated checklists of
amphibians and reptiles of China. Biodiversity Science 28(2): 189–218.
Wangyal, J.T. (2011). Snakes and lizards from Bumdeling Wildlife Sanctuary region of Bhutan. Review of herpetofaunal information and new country records. Herpetological
Review 42: 117–122.
Wangyal, J.T. (2012). New records of snakes and
lizards from Bhutan. Hamadryad 36(1):
25–31.
Wangyal, J.T. (2013). New records of reptiles and
amphibians from Bhutan. Journal of Threatened Taxa 5(13): 4774–4783. https://doi.org/10.11609/JoTT.o3539.4774-83
Wangyal, J. (2014). The status of herpetofauna of
Bhutan. The Journal of Bhutan Ecological Society 2(1): 20–39.
Wangyal, J.T. & D.B. Gurung (2017). The Current Status of
Herpetofauna in Bhutan, pp. 39–55. In: Gurung, D.B. & O. Katel (ed.). Introduction to the Biodiversity of Bhutan
in the Context of Climate Change and Economic Development. Centre for Rural
Development Studies. College of Natural Resources, Lobesa,
Punakha. Kuensel Corporation Limited, 200pp.
Wangyal, J.T. & K. Tenzin (2009). Snakes and lizards [sic]
diversity in Bumdeling Wildlife Sanctuary, Choetenkora,
Trashiyangtse. Thimphu,
Bhutan, Kuensel Corporation, 103pp.
Wangyal, J.T., D.S. Bower, Sherub, S. Tshewang, D. Wangdi, K. Rinchen, S. Phuntsho, C. Tashi, B.K. Koirala,
Gyeltshen, G.S. Bhandari, S. Jamtsho,
Y. Phuntsho, T.P. Koirala, B.B. Ghalley,
L. Chaida, J. Tenzin, R.B. Powrel,
R. Tshewang, O.N. Raika, S.
Jamtsho, Kinley, Gyeltshen,
S. Tashi, D. Nidup, N. Wangdi, Phuntsho, L. Norbu, K. Wangdi, T. Wangchuk, P.
Tobgay, T. Dorji & I.
Das (2020). New herpetofaunal records from the Kingdom of Bhutan obtained
through citizen science. Herpetological Review 51(4): 790–798.
Whitaker, R.
& A. Captain (2004). Snakes of India. The Field Guide. Draco Books, P.O. Box 21,
Chengalpattu, Tamil Nadu, India, 481pp.