Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 July 2020 | 12(10): 16347–16351
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
doi: https://doi.org/10.11609/jott.3378.12.10.16347-16351
#3378 | Received 27 February 2017 | Final
received 21 June 2020 | Finally accepted 30 June 2020
A threat assessment of
Three-striped Palm Squirrel Funambulus palmarum (Mammalia: Rodentia: Sciuridae)
from roadkills in Sigur
Plateau, Mudumalai Tiger Reserve, Tamil Nadu, India
Arockianathan Samson 1, Balasundaram Ramakrishnan 2 & Jabamalainathan Leonaprincy
3
1 Vulture Programme, Bombay Natural
History Society, Mumbai, Maharashtra 400001, India.
2 Mammalogy and Forest Ecology, 3
Herpetology and Tribal Medicine Lab,
Department of Zoology and
Wildlife Biology, Government Arts College, Udhgamandalam,
Nilgiris, Tamil Nadu 643002, India.
1 kingvulture1786@gmail.com
(corresponding author), 2 bio.bramki@gmail.com, 3 leonaprincymsc@gmail.com
Editor: Anonymity
requested. Date of publication:
26 July 2020 (online & print)
Citation: Samson, A., B. Ramakrishnan
& J. Leonaprincy (2020). A threat assessment of
Three-striped Palm Squirrel Funambulus palmarum (Mammalia: Rodentia: Sciuridae)
from roadkills in Sigur
Plateau, Mudumalai Tiger Reserve, Tamil Nadu, India. Journal of Threatened Taxa 12(10): 16347–16351. https://doi.org/10.11609/jott.3378.12.10.16347-16351
Copyright: © Samson et al. 2020. 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: None.
Competing interests: The authors
declare no competing interests.
Acknowledgements: Our whole hearted thanks to the
Principal Chief Conservator of Forests and Chief Wildlife Warden of Tamil Nadu
state for giving us necessary permission to carry out the field work. Our
special thanks are due to the District Forest Officer, Nilgiri
North Forest Division for providing permission and all logistic supports to
carry out the field work. This observation record is part of the long term
study on the project entitled “Conservation strategies for securing critically
endangered White-rumped Vulture Gyps bengalensis and Long-billed Vulture Gyps indicus species in
the Tamil Nadu part of the Nilgiri Biosphere Reserve”
funded by the Raptor Research & Conservation Foundation (RRCF). We thank
our field assistant Mr. R. Bomman, B. Vishnu, K.
Manikandan and P. Prabhu for taking lot of pain in
collecting field data in the forests amidst elephants. Special thank to Ravi. P Naturalist for the support and
encouragement in the field work.
Abstract: This study was undertaken to assess the threat from road kills for
three-striped palm squirrels in the tropical forest of Sigur
plateau, Mudumalai Tiger Reserve, Tamil Nadu, and
Southern India from January 2014 to December 2016. Road kills were recorded along the
Udhagamandalam to Masinagudi state highway passing
through Mudumalai Tiger Reserve (40 km). Four visits
per month were carried out mostly on weekends (Saturday or Sunday). A total of 497 three-striped palm squirrel
kills were recorded, with an overall rate of 0.09/km of the roadway. Habitat
wise 387 kills were observed in the thorn forest and 110 in dry deciduous
forest habitats. Season wise 176 kills were recorded in winter, 156 in summer,
83 post-monsoon, and 82 during the monsoon.
The study distinguished the ongoing major threat on the three-striped
palm squirrel in the present scenario.
Keywords: Deciduous forest, ecology,
habitat loss, mortality, vehicle movements.
The Three-striped Palm Squirrel Funambulus palmarum
is a small rodent of the Sciuridae family, with four
subspecies native to India and Sri Lanka.
F. palmarum is endemic to southern
India and Sri Lanka (Thorington & Hoffmann 2005; Nameer & Molur 2008), where
it is widely distributed from sea level to 2,000m (Nameer
& Molur 2014).
Squirrels can reach head-body length of 12–15 cm and tail length of
14–15 cm (Menon 2014), and they
have short fur that is yellowish-brown or brown on the back and creamy white on
the belly (Menon 2014). Three white
stripes on the back stretch from the head to tail. F. palmarum
has dark round eyes, small triangular ears, long front teeth, and a bushy tail
(Figure 1a; Prater 1971; Menon 2014; Pradhan & Talmale
2012). It is an omnivore with a diet
based largely on fruit and nuts that also includes eggs, small birds, larvae,
and insects (Prasad et al. 1966; Malhi & Kaur
1994; Malhi & Khushrupinder
1995). Squirrels mate throughout the
year and build nests in treetops using grass and branches. Pregnancy lasts 34 to 45 days and produces
1–5 offspring; young are fully weaned at 10 weeks and reach sexual maturity at
nine months. Animals can survive up to
four years in the wild and >5 years in captivity (Weigl
2005). This study was undertaken to
assess the threat to Three-striped Palm Squirrels from roadkills
in the tropical forest of Sigur Plateau, Tamil Nadu
in southern India.
Study Area
Sigur Plateau is located in Mudumalai Tiger Reserve.
It is a connective junction of Western and Eastern Ghats and harbors a
diverse range of wildlife that includes Asian Elephant Elephas maximus,
Tiger Panthera tigris,
Leopard Panthera pardus,
Gaur Bos gaurus, Chital Axis axis, Sambar Rusa unicolor,
and other mammals (Ramakrishnan & Saravanamuthu
2012), as well as birds such as Endangered and Critically Endangered vultures
including the Long-billed Vulture Gyps indicus, White-rumped Vulture Gyps bengalensis,
Red-headed Vulture Sacrogyps calvus,
and Egyptian Vulture Neophran percnopterus (Ramakrishnan et al. 2014; Samson et al.
2014, 2015). The corridor between the
Western and Eastern Ghats is used by elephants, tiger, gaur, and other
herbivores for seasonal migrations influenced by the southwest and northeast
monsoons. The major streams of Sigur Plateau are the Moyar
River, the Sigur River, the Avarahalla
River, the Kedarhalla River, and the Gundattihalla River, which crisscross the Moyar Valley and drain into the Bhavanisagar
Reservoir. Villages located within the Sigur Plateau are home to local communities and more
recently to several tourist facilities that subsist mainly on the attractions
of the diverse wildlife in the area surrounding Mudumalai
Tiger Reserve.
Methods
Roadkills were recorded along the
Udhagamandalam–Masinagudi state highway passing
through Mudumalai Tiger Reserve (40km) (Figure
1). The local habitats are classified as
dry thorn forest and dry deciduous forest (Gokula
& Vijayan 1996; Ramakrishnan & Saravanamuthu
2012). Four visits per month were carried
out between January 2014 and December 2016, mostly on weekends (Saturday or
Sunday) by an observer and driver on a motorbike traveling at 10–15 km/h;
observation times alternated between morning (06.00–08.00 h) and evening
(16.00–18.00 h). Intermittent roadkills were also observed by forest officials and
drivers, which when verified were included in the totals. For each kill the information recorded
included the location, surrounding area (forest, human habitation, plantation),
habitat type, and state & sex of dead animals, which when possible were
removed from the road to avoid recounting.
Results
A total of 497 individual
Three-striped Palm Squirrels (Figure 1; Image 1) were recorded as roadkill
victims in 144 visits covering 5,760km, for an encounter rate (ER) of 0.09
individuals/km/month. Most kills were
recorded as fresh (n=307). Males (n=220)
were more frequently observed than females (n=145), although many were unidentified
(n=132; Figure 1).
Three-hundred-and-eighty-seven kills were observed over 33km of road in
thorn forest habitats (ER=0.08 individuals/km/month), and 110 in dry deciduous
forest (7km; ER=0.11 individuals/km/month) (Table 2). More roadkills were
recorded in forest habitats (n=354; ER=0.078 individuals/km/month) followed by
human habitation (n=89; ER=0.08 individuals/km/month), and plantations (n=54;
ER=0.57 individuals/km/month). The
roadkill results show significant variation R2=0.995 year by year
2014 (n=148; 12.33±1.25; ER=0.08 individuals /km/month), 2015 (n=165; 13.75±1.55;
ER=0.08 individuals/km/month), and 2016 (n=184; 15.33±1.58; ER=0.10
individuals/km/month) (Figure 2).
Month-wise analyses of the roadkills show that
May (n=75; 25±1.15) had more number of roadkills
followed by December (n=61; 20.33±1.76), April (n=48; 16±1.15), November (n=47;
15.66±1.45) March (n=42; 14±1.15), and January (n=41; 13.66±1.45) (Figure 2);
and significant variations were observed between month-wise data and the
year-wise data (F=11.12 p= 0.005). The
season-wise data revealed that winter (December–March) (n=176; 14.66±1.19; ER=
0.09 individuals/km/month) and summer (pre-monsoon) (April–June) (n=156;
17.33±2.12; ER= 0.11 individuals/km/month) seasons recorded more kills compared
to post-monsoon (October–November) (n=83; 9.11 ± 0.78; ER= 0.09
individuals/km/month) and monsoon seasons (July–September) (n=82; 13.83±1.07;
ER= 0.06 individuals/km/month) (Figure 3; Table 1).
Discussion
This study targeted a single
species affected by linear construction like road networks. In fragmented habitats, linking route ways
enhance the movements of small mammals (Coffman et al. 2001). Medium and large-sized mammals are
particularly at risk, especially when the emergence of young coincides with
high traffic volumes (Oxley et al. 1974).
The present study shows that males are frequently killed rather than
females. Linear construction appears to
affect the movement of males and females (Davis-Born & Wolff 2000). Various species show seasonal peaks in
accident rates often with a higher percentage of males being killed (Davies et
al. 1987; Rotar & Adamic 19975; van Langevelde & Jaarsma 1997;
Mead 1997; Reeve & Huijser 1999). This suggests that breeding or dispersal behavior may be partly responsible (Moshe & Mayer
1998). Three-striped Palm Squirrel live in
diverse habitats but mainly occur in tropical forests and around human
habitation (Molur et al. 2005). The present study was carried out in two
different vegetation structures in Sigur
Plateau. Thorn forest had more roadkills compared to dry deciduous forest which indicated
that Three-striped Palm Squirrels utilized thorn forest vegetation more. A considerable amount of roadkills
was observed in human habitation as well as plantations. Three-striped Palm Squirrels are easily tamed
by humans and easily adapt to human habitation, plantations , and gardens (Molur et al. 2005).
Sunbathing is one of the key
activities for striped squirrel at dawn and dusk (Mendez-Carvajal et al.
2016). Samson et al. (2016) recorded
that most fresh roadkills of Three-striped Palm
Squirrel are observed at dawn and dusk in the present study also corroborate
the previous study indicating that Three-striped Palm Squirrel use the road
surface for sunbathing, it seemed to be the reason for the high death rate. Some incidences may have occurred related to
eating the insect on the roads. The road
and road allowances attract prey populations, in particular, small mammals and
carrion, but also insects and worms that are washed out of the soil onto roads
(Tabor 1974). According to the
literature, individuals from this genus prefer insects as protein sources more
than fruits and nuts when fruits and vegetation are in the same proportions (Prater 1971; Barnett & Prakash 1975; Tiwari 1990;
Balasubramanian 1995; Parasara et al. 1997).
Winter and summer seasons
recorded Three-striped Palm Squirrel roadkills
because of very high traffic on the state highway passing through the Nilgiri North Forest Division at one end connected to the
Interstate highway NH 67 at Theppakadu and Ooty on other end.
Generally, winter and summer are the best seasons to visit
Udhagamandalam and that is a reason for high vehicular traffic intensity
resulting in the high number of roadkills. Similarly, significant number of roadkills were also found in Mudumalai
Tiger Reserve due to local vehicular movement as well as wildlife safaris
(Samson et al. 2016)
According to the literature,
habitat loss and degradation due to agro-industry
farming, small-scale logging, human encroachments, invasive alien species, and
hunting for local consumption purposes are minor threats to the Three-striped
Palm Squirrel population (IUCN Red List Data 2016). The present study explored the current major
threat in the present scenario. An
urgent long-term study is needed to better understand the impact of roads on the ecology of the Three-striped
Palm Squirrel.
Table 1. Season-wise roadkills of Three-striped Palm Squirrel in Sigur Plateau in Mudumalai Tiger
Reserve.
Seasons |
Totals |
M±SE |
ER |
Winter (December–March) |
176 |
14.66±1.19 |
0.10 |
Summer (April–June) |
156 |
17.33±2.12 |
0.11 |
Monsoon (July–September) |
82 |
9.11±0.78 |
0.06 |
Post Monsoon (October–November) |
83 |
13.83±1.07 |
0.09 |
Table 2. Habitat-wise roadkills of Three-striped Palm Squirrel in Sigur Plateau in Mudumalai Tiger
Reserve.
Vegetation |
Km |
Total km |
Totals |
M±SE |
ER |
Thorn Forest |
33 |
4752 |
387 |
32.25±3.28 |
0.08 |
Dry Deciduous Forest |
7 |
1008 |
110 |
9.16±1.09 |
0.11 |
For
figures & image - - click here
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