The Three-striped Palm Squirrel, Funambulus palmarum, is a small Rodent of the Sciuridae family, with four subspecies native to India and Sri Lanka. Funambulus palmarum is endemic to southern India and Sri Lanka, where it is widely distributed from sea level to 2000 m. Squirrels can reach head-body length of 12–15 cm and tail length of 14–15 cm, and they have short fur that is yellowish-brown or brown on the back and creamy white on the belly. Three white stripes on the back stretch from the head to tail. Funambulus palmarum has dark round eyes, small triangular ears, long front teeth, and a bushy tail. It is an omnivore with a diet based largely on fruit and nuts that also includes eggs, small Birds, larvae, and Insects. 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 over 5 years in captivity.
In a paper published in the Journal of Threatened Taxa on 26 July 2020, Arockianathan Samson of the Vulture Programme of the Bombay Natural History Society, Balasundaram Ramakrishnan of Mammalogy and Forest Ecology, and Jabamalainathan Leonaprincy at the Herpetology and Tribal Medicine Lab of the departments of Zoology and Wildlife Biology at the Government Arts College, Udhgamandalam, present the results of a study which 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.
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, as well as Birds such as Endangered and Critically Endangered Vultures including the Long-billed Vulture, Gyps indicus, Whiterumped Vulture, Gyps bengalensis, Red-headed Vulture, Sacrogyps calvus, and Egyptian Vulture, Neophran percnopterus. 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.
Roadkills were recorded along the Udhagamandalam–Masinagudi state highway passing through Mudumalai Tiger Reserve (40km). The local habitats are classified as dry thorn forest and dry deciduous forest. 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 per hour; observation times alternated between morning (6.00–8.00 am) and evening (4.00–6.00 pm). 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.
A total of 497 individual Three-striped Palm Squirrels were recorded as roadkill victims in 144 visits covering 5760km, for an encounter rate of 0.09 individuals/km/month. Most kills were recorded as fresh (307). Males (220) were more frequently observed than females (145), although many were unidentified (132). Three-hundred-andeighty-seven kills were observed over 33 km of road in thorn forest habitats (an encounter rate of 0.08 individuals/km/month), and 110 in dry deciduous forest (7 km; an encounter rate of 0.11 individuals/km/month). More roadkills were recorded in forest habitats (354; an encounter rate of 0.078 individuals/km/month) followed by Human habitation (89; an encounter rate of 0.08 individuals/km/month), and plantations (54;an encounter rate of 0.57 individuals/km/month). The roadkill results show significant variation year by year 2014 (148; 12.33 ± 1.25; an encounter rate of 0.08 individuals /km/ month), 2015 (165; 13.75 ± 1.55; an encounter rate of 0.08 individuals/ km/month), and 2016 (184; 15.33 ± 1.58; an encounter rate of 0.10 individuals/km/month). Month-wise analyses of the roadkills show that May (75; 25 ± 1.15) had more number of roadkills followed by December (61; 20.33 ± 1.76), April (48; 16 ± 1.15), November (47; 15.66 ± 1.45) March (42; 14 ± 1.15), and January (41; 13.66 ± 1.45); and significant variations were observed between month-wise data and the year-wise data. The season-wise data revealed that winter (December–March) (176; 14.66 ± 1.19; an encounter rate of 0.09 individuals/km/month) and summer (premonsoon) (April–June) (156; 17.33 ± 2.12; an encounter rate of 0.11 individuals/km/month) seasons recorded more kills compared to post-monsoon (October–November) (83; 9.11 ± 0.78; an encounter rate of 0.09 individuals/km/month) and monsoon seasons (July–September) (82; 13.83 ± 1.07; an encounter rate of 0.06 individuals/km/month),
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. Medium and large-sized Mammals are particularly at risk, especially when the emergence of young coincides with high traffic volumes. Samson et al.'s study shows that males are frequently killed rather than females. Linear construction appears to affect the movement of males and females. Various species show seasonal peaks in accident rates often with a higher percentage of males being killed. This suggests that breeding or dispersal behavior may be partly responsible. Three-striped Palm Squirrel live in diverse habitats but mainly occur in tropical forests and around human habitation. 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 utilised 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.
Sunbathing is one of the key activities for Striped Squirrel at dawn and dusk. A previous study 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. 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.
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.
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. 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.
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