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36ОРИГИНАЛЬНЫЕ СТАТЬИ RESEARCH ARTICLES
AN INVENTORY OF ROADKILLS OF NOCTURNAL MAMMALS IN COONOOR GHAT HIGHWAY NH 67, THE NILGIRIS, WESTERN GHATS,
INDIA
A. Samson*, J. Leona Princy
Department of Zoology and Wildlife Biology, Government Arts Collage, India e-mail: *kingvulture1786@gmail.com
Received: 24.11.2022. Revised: 09.01.2023. Accepted: 02.02.2023.
This study was conducted on a 30 km stretch of the Coonoor Ghat National Highway 67 (Coonoor - Burliar - Kallar - Mettupalayam) over a one-year period from October 2016 to September 2017 to assess the impact of vehicular traffic on nocturnal mammals. During twice monthly surveys (24 in total) an observer and driver rode a motorbike at 10-15 km/h, hand recorded roadkills observed on either side of the road. A total of 118 roadkill were observed from three orders and seven families, with Carnivora recorded most often. Of 11 roadkill species recorded, six were arboreal and five were terrestrial. Eighty-six per cent of roadkill were terrestrial species, with major victims being the Greater Bandicoot Rat (n = 56) and House Rat (n = 25). The largest number of roadkill was observed in human habitations (n = 66), as oppose to forest area (n = 52). Seasonal data showed the highest amount of roadkill in winter (December - March; n = 39) and summer (April - June; n = 32).
Key words: highway, India, nocturnal mammals, roadkill, traffic https://dx.doi.org/10.24412/cl-31646-2686-7117-2023-32-68-76
Introduction
Animal mortality on roads due to collisions with vehicular traffic (wildlife roadkill) is among the most direct and visible negative impacts of roads. Studies have shown that demographic effects of roadkill on wildlife populations may be as serious and significant as those due to direct habitat loss in Massachusetts (USA) suburban highway (Forman et al., 2003). Fragmentation of habitat by roads and the frequent passage of vehicles on them act as physical barriers for species dispersal across a range of taxa (Carr & Fahrig, 2001; Laurance, 2004; Goosem, 2007). Animal abundance and population structure is often affected by road mortalities resulting from frequent vehicular movement (Fahrig & Rytwinski, 2009). These negative effects of roads are not limited to the road itself, but often extend to nearby areas (Forman & Deblinger, 2000; Trombulak & Frissell, 2000; Eigenbrod et al., 2009). Road mortalities are primarily influenced by habitat variability along the road corridor (Inbar & Mayer, 1999; Seshadri et al., 2009). Vehicular movements at night are considered to substantially increase mortality in nocturnal animals like amphibians (Mazerolle, 2004). The possible synergistic effects of the aforementioned factors could increase negative impacts on populations.
Vehicular densities on Indian roads have increased from 0.3 to 30 million in the last 50 years, and many roads pass through protected areas and non-protected areas (Raman, 2009; Seshadri et al., 2009). The Western Ghats of India, a global biodiversity hot spot, is known for high endemism of flora and fauna. There are few scientific studies in India on the impact of these roads inside PA's (Gokula, 1997; Kumara et al., 2000; Vijayakumar et al., 2001; Chhangani, 2004a,b; Rao & Girish, 2007; Seshadri et al., 2009; Baskaran & Boominathan, 2010; Pragatheesh, 2011; Seshadri & Ganesh, 2011; Samson et al., 2016, 2020). Information on wildlife roadkills outside protected areas in India is scarce (Santhoshkumar et al., 2016, 2017; Santhoshkumar & Kannan, 2017; Jeganathan et al., 2018), although some studies have reported specific taxa including amphibians (Vijayakumar et al., 2001; Seshadri, 2009; Santhoshkumar et al., 2017), reptiles (Vijayakumar et al., 2001; Nagar et al., 2013; Chittaragi & Hosseti, 2014; Santhoshkumar et al., 2016, 2017; Santhoshkumar, Kannan, 2017), birds (Chhangani, 2004a,b; Siva & Neelanarayanan, 2020) and mammals (Chhangani, 2004a,b; Pragatheesh, 2011; Samson et al., 2020).
Ecotone regions are biogeographically important for two reasons. Firstly, they are generally species-rich (Kark et al., 2006). Secondly, they sometimes exhibit complex mosaic patterns in geography or vegetation. The present study investigated an ecotone region containing the Coonoor Ghat Highway NH 67 in the Nilgiris, which is highly utilized for tourist purposes as well as transportation, to assess roadkill of nocturnal mammals from October 2016 to September 2017.
Material and Methods
Study area
The Nilgiri district is one of the smallest in Tamil Nadu, with an area of 2549 km2 located between 11.166667° N and 11.5° N latitude, and 76.416667° E and 77° E longitude. The district has 152 km of interstate highways, 143 km of major state roads, 757 km of district roads and 250 km of panchayat roads. The district is on a mountainous plateau formed at the junction of the Eastern Ghats and Western Ghats. The elevation ranges between 300 and 2700 m above m.s.l. The maximum temperature ranges between 21 °C and 25 °C in summer, while during winter the minimum temperature ranges between 10 °C and 12 °C. The major vegetation of the Nilgiris consists of montane shola, grasslands and plantations of exotic species such as wattle (Acacia spp.), blue gum (Eucalyptus spp.) and pine (Pinus spp.). Most of the roads in the district bisect heavily forested mountains and have several sharp hairpin bends. Coonoor Ghat, also known as Kallar Ghat, on National Highway 67 (Coonoor - Burliar - Kallar - Mettupalayam) is 34 km (Fig. 1) long and passes through the valley of the Kallar and Coonoorrivers.
Methods
The study was conducted over one-year period, from October 2016 to September 2017 on a 30 km stretch of the Coonoor Ghat National Highway 67
running from Coonoor to Burliar, Kallar and Mettupalayam (Fig. 1). Surveys were done twice a month for a total of 24 visits by an observer and driver riding a motorbike at 10-15 km/h during the early morning hours (06.00-09.00) and late evening hours (16.00-18.00) on alternate days to record the nocturnal mammals' number of roadkills observed. Habitats were divided into two categories: human habitation (12 km) and forest (18 km). On observing a roadkill, the species was identified using a field guide (Menon, 2014), and noted along with the status of the carcass (fresh/old), which was then removed to avoid recounting.
Fig. 1. Coonoor Ghat National Highway NH 67 (30km), Nilgiris, Western Ghats, India.
Statistical Analysis
The mean and standard error were calculated for the analysis of the roadkill per visit. The encounter rate was also calculated, taking into consideration the number of roadkills per km. T test was performed to understand the differences between the roadkills in the two habitats. Pearson's correlation coefficient test was performed to assess the relationship of habitat-specific roadkills. The Kruskall-Wallis test was carried out to analyze the differences between the seasons. Statistical analysis was carried out with the help of the Graph Pad Prism 5 Statistical Software.
Results
A total of 118 kills were observed over a 24-day period and a total distance covered of 720 km, for an overall mean of 4.91 ± 0.33 kills/day and an overall ER of 0.16/km/day. Kills were recorded from three orders and seven families; Carnivora was the most common order, followed by Rodentia and Lagomorpha (Fig. 2, Table). Among families the Viverridae, Felidae and Muridae were represented by two species each, and Herpestidae, Leoporidae, Sciuridae and Hystricidae by one species
■ Carnivora
■ Lagomorpha
■ Rodentia
Fig. 2. Order distribution of roadkills of nocturnal mammals.
Table. Roadkills by Order, Family and Species
S.No Order Family Common Name Scientific Name IUCN Status Total ER/Km
1 Small Indian Civet Viverricula indica LC 3 0.004
2 Viverridae Asian Palm Civet Paradoxurus hermaphroditus LC 4 0.006
3 Carnivora Brown Palm Civet Paradoxurus jerdoni LC 1 0.001
4 Felidae Jungle Cat Felis chaus LC 2 0.003
5 Leopard Cat Prionailurus bengalensis LC 3 0.004
6 Herpestidae Indian Grey Mongoose Herpestes edwardsi LC 6 0.008
7 Lagomorpha Leporidae Indian Hare Lepus nigricollis LC 12 0.017
8 Sciuridae Indian Giant Flying Squirrel Petaurista philippensis LC 4 0.006
9 Rodentia Muridae Greater Bandicoot Rat Bandicota indica LC 58 0.081
10 House Rat Rattus rattus LC 26 0.036
11 Hystricidae Indian Crested Porcupine Hystrix indica LC 2 0.003
Total 118 0.164
each (Table). Of 11 roadkill species recorded, six were arboreal and five terrestrials. Overall, 86% of roadkills (n = 101) were of terrestrial species and 14% (n = 17) of arboreal species. During the survey, 89 roadkill carcasses were recorded to be fresh.
The Greater Bandicoot Rat (N = 56) and House Rat (n = 25) were the major victims, while The Brown Palm Civet (n = 1), Jungle Cat (n = 2), Indian Crested Porcupine (n = 2) and Leopard Cat (n = 3) were the least recorded species (Table). Based on IUCN criteria, all 11 recorded species were under the 'Least Concern' category (IUCN, 2020). With regard to habitat, the largest number of roadkills were observed in human habitations (n = 66), and there was no statistically significant difference among month-wise roadkills in these habitats. Pearson correlation shows a negative correlation between the roadkills of the two habitat types (r = -186, P = 0.586). Month-wise analyses of roadkills showed that April (n = 13) had the most kills, followed by May (n = 12), September, October, December and January with 11 kills each (Fig. 3). Season-wise data revealed that winter (December - March; n = 39) and summer (pre-monsoon, April - June; n = 32) had higher kills compared to monsoon (October - November; n = 26) and post-monsoon seasons (July - September; n = 21) (Fig. 3; Table).
0,25
0,20
0,15
£ ОС
0,10
y = -0,0029x + 0,1828 R2 = 0,1001
• ER/km
-Линейная (ER/km)
0,05
0,00
0123456789 10 11 12 Months October 2016 to September 2017
Fig. 3. Roadkills of nocturnal mammals by month.
Discussion
The present study examined the effect of vehicular traffic on nocturnal mammals in a region that was not surveyed by previous studies of the Nilgiris (Baskaran & Boominathan, 2010; Samson et al., 2014, 2016, 2017, 2020). We found both terrestrial and arboreal mammals among the victims of vehicular traffic, most likely owing to their crossing the road to reach forest fragments (Seiler et al., 2004; Samson et al., 2014). The most affected species were observed to be the Greater Bandicoot Rat and Field Rat, and most roadkills were observed in the human habitation stretch of the highway. Since these are both nocturnal species, their movement would take place in the late evening and night, when most deaths occurred
(Baskaran & Boominathan, 2010; Samson et al., 2016). The roads offer plenty of food to these rodents, including rubbish thrown by car passengers, contributing to the likelihood of roadkills (Samson et al., 2016). The study of Hatti & Mubeen (2019) which covered the roadkills on the route from Kalaburagi to Chincholi, Karnataka, reported that most of the mammalian species killed on the road were nocturnal (Jungle Cat, Small Indian Civet, Asian Palm Civet, Indian Grey Mongoose, Indian Hare, Porcupine). Our study also found the Jungle Cat, Leopard Cat, Brown Palm Civet, Asian Palm Civet, Small Indian Civet, Indian Grey Mangoose, and Indian Crested Porcupine as roadkills at nighttime. This indicates that these species are quite vulnerable to becoming roadkills at night. Most of the roadkills were observed in forest areas. Mortality was high in areas where there was thick vegetation on either side of the road (Selvan et al., 2012) and there was a tendency of mammals to be killed in dense forests (Clevenger & Kociolek, 2006).
The winter and summer seasons recorded the highest number of roadkills. A similar observation was made in a study involving Three-stripe Palm Squirrel in Mudumalai Tiger Reserve (Samson et al., 2020). Furthermore, the reason behind the heavy traffic on this highway is that it connects Mettupalayam and Udhagamandalam, a famous tourist post in Tamil Nadu, India.
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ИНВЕНТАРИЗАЦИЯ ГИБЕЛИ НОЧНЫХ МЛЕКОПИТАЮЩИХ НА НАЦИОНАЛЬНОЙ МАГИСТРАЛИ КУНУР ГАТ 67, НИЛГИРИС, ЗАПАДНЫЕ ГАТЫ, ИНДИЯ
Арокианатан Самсон*, Джабалаинатан Леона Принси
Кафедра зоологии и биологии дикой природы Государственного художественного
колледжа, Утхагамандалам, Индия e-mail: *kingvulture1786@gmail.com
Исследование проводилось на 30-километровом участке национальной автомагистрали Кунур Гат 67 (Кунур - Бурлиар - Каллар - Меттупалаям) с октября 2016 г. по сентябрь 2017 г. для оценки воздействия автомобильного движения на ночных млекопитающих. Во время исследования два раза в месяц (всего 24 раза) наблюдатель и водитель ехали на мотоцикле со скоростью 10-15 км/ч, вручную фиксировали дорожно-транспортные происшествия с участием ночных млекопитающих, наблюдаемые по обе стороны дороги. Всего было замечено 118 дорожно-транспортных происшествий с участием животных из трех отрядов и семи семей, причем чаще всего регистрировались Carnivora. Из 11 зарегистрированных видов, погибших на дорогах, шесть были древесными и пять - наземными. 86% погибших на дорогах животных были наземными видами, при этом основными жертвами стали большая бандикутская крыса (n = 56) и домашняя крыса (n = 25). Наибольшее количество дорожно-транспортных происшествий наблюдалось в жилых районах (n = 66), в отличие от лесной
зоны (п = 52). Сезонные данные показали, что наибольшее количество погибших на дорогах животных встречается зимой (декабрь - март; п = 39) и летом (апрель - июнь; п = 32). Ключевые слова: дорожное движение, дорожно-транспортное происшествие, Индия, ночные млекопитающие, шоссе
