Highways the Death Door of Wild Life: A Comprehensive Study in Indian Thar Desert

: Highways play a crucial role in economic development of any country. Besides this, highways are also one of the causal agents of wild life destruction. The present investigation was based on the study of mortality rate in some selected wild animal groups in road accidents viz., Mammals, Birds and Reptiles on the national and state highways passing through the Indian Thar Desert, and the survey of biodiversity of roadside fauna and flora. The survey was also focused on the effects of highways on the population density and biodiversity of the area. Among the selected animal groups Mongoose, Squirrel, Wild Boar, Hedgehog, Chinkara, Desert fox, Nilgai, Greater Coucal (Crow Pheasant), Sparrow, Partridge, Babbler, White eared and Red Vented Bulbul, Peacock, Desert Monitor , Garden Lizzard, Skinks, Cobra, Vipers etc. were found killed in the road accidents. Maximum mortality rate in the road accidents during the survey was observed in Mongoose, Greater Coucal and Desert monitor ( Varanus ) throughout the study period. It was experienced that unavailability of safe passes across the highways, negligence driving and over speed of the vehicles were the major causes of wild life destruction on the highways. Maximum mortality rate of wild animals was found in July to November in each calendar year and minimum was during the month December to February. By the present investigation it was suggested that making transverse tunnels across the highways at regular interval, warning signboards about the wild life abundance regions, awareness among the drivers for wildlife protection and covering the road sides with net fencing in wild life abundant areas may reduce some degree of wildlife destruction in road accidents.


INTRODUCTION
The road transportation infrastructure comprises the express ways, national and state highways, district road and local roads within cities, towns and villages. There are two types of highways in India, the National highways which are constructed and operating by the National Highway Authority of India (NHAI) and the State highways which are operating by Public Works Department (PWD) of concerned state governments.
As per ministry of Road transport and Highways, India has 144,955 km of national highways as on 31 Dec. 2022. [1] It constitutes about 3% of the total road network of India, and 40% of total road traffic load bears. National highways are passed through many national parks, sanctuaries, biodiversity hot spots and other bio-reserves. On these national highways and express ways, thousands of the goods truck, buses, four wheelers and two wheelers vehicles are passing round the clock. Road Transportation infrastructure is an important criterion for development of any country. In India, road transportation imparts 4.7% of the total GDP. On the contrary, these highways are also a major cause of wildlife destruction. When the wild animals crossing these roads in search of water, food, shelter, mates etc., they accidently got injuries or died by hitting speedy vehicles. Total 52 National highways passing through the Rajasthan having total length of 10,706.34 km, out of which national highway number NH-11, NH-25, NH-125, NH-62, NH-65 are passing through the region of Thar Desert. [1] More "importantly" the Desert National park which is famous for critically endangered great Indian Bustard is situated in this region.
Apart from the national highways there are 170 state highways having the total length of 15517 km as on 31.03.2019 and among these SH-16, SH-19, SH-20, Sh-28, 28B, SH-31, SH-36, SH-38, SH-40, SH-58, SH-61, SH-62, SH-63, SH-64, SH-65, Sh-66, Sh-68, Sh-69 are passing through the Indian Thar Desert. [2] The area covered by these highways are rich in Biodiversity. Many wild animals are residing or habitat in forest land, Gauchar Bhumi and farmland boundaries at flank of these highways e.g. Nilgai (Boselaphus tragocamelus), Indian gazelle (Gazella gazella), blackbuck (Antelope cervicapra), desert fox (Vulpes vulpes), wild boar (Sus scrofa cristatus), Desert cat (Felis silvestris ornata), Jungle cat (Felis chaus affinis) Mongoose (Herpestes edwardsi), Hedgehog (Paraechinus aethiopicus), Indian Crested Porcupine (Hystrix indica), critically endangered Great Indian bustard (Ardeotis nigriceps), migratory bird Demoiselle crane (Anthropoides virgo), Peacock (Pavo cristatus), Greater coucal (Centropus sinensis), Sparrow (Passer domesticus); reptiles (Varanus griseus), Garden Lizard Calotes versicolor), Spiny tailed lizard (Uromastyx hardwickii), Toad headed lizard (Bufoniceps laungwalaensis) Cobra (Naja naja), Red sand boa (Eryx johnii), Saw-Scaled Vipers (Echis carinatus) ect. are common animals found in this region. [3,4] These wild animals are important genetic resources of the country and deeply integrated in ecosystem stability of this harsh region, but Dozens of killed animals by road accidents can be seen every day on these highways which drastically disturb the food chain and food web of the area. These accidents took place by the heavy as well as light vehicles passed on these highways. Reduction in biodiversity and animal population by these accidents may deteriorate or make unstable the ecosystem. Hence the present investigation was done to know the mortality rate of wild animals by road accidents on highways and impact of these highways on Fauna and Flora of the region.

MATERIAL AND METHODS
For study of the present work, the following methods have been followed.
1) The Random field survey was carried out by direct observation and the quadrate methods for the study of biodiversity and the population density. 2) Study area -National and State highway passing through the Thar Desert of India (Jodhpur, Bikaner, Jaisalmer and Barmer), national highway NH-11 (From Bikaner to Jaisalmer) and State highways-SH-61 (From Jodhpur to Phalodi) were surveyed randomly (Fig. 1).
3) The data were collected in the calendar year 2019-2022 in three replicas in each month. The dead animals including Reptiles, Aves and Mammals were counted and recorded at every 10 kilometer.    Table 2.

Mortality rate of wild animal's on the National Highways
The mortality of wild animals in road accidents on the studied National highways was recorded throughout the calendar year. The present study revealed that the number of Mammalian wild fauna killed in road accidents was highest in July to September month (4-7 animals/10km) of the year while the minimum death was recorded during March to June (1-2.33 animals/10km). Likewise, birds found dead on the roads was maximum in August to November (3.33-5 animals/10km), whereas minimum destruction was found in the months of December to February (1-2 animals/10km). On the other hand, Reptilian crushed on the roads were found highest in July to September (5-7 animals/10km) month whereas, minimum reptiles were found dead during the month of December to March (0-3 animals/10km). It may be due to their minimum activities or goes into hibernation during the winter season. This finding is support the work of Cloudsley-Thompson (1999). [9] The mortality data are documented in (Table 3). There are two peaks of total mortality of wild animals on the highways are seen, one small peak in the months of March-April and another high peak observed during July-September ( Figure 2). This was due to their highest population density achieved by the breading during the favorable rainy season and maximum activities for feeding and mating around the roadside habitats.

Mortality rate of wild animal's on the State Highways
The knockdown of wild animals by speedy vehicles on the State highways was calculated throughout the year of 2019-2022. The study showed that the number of Mammalian wild fauna killed in road accidents found highest in July to September month (3-7 animals/10km), while the minimum death was recorded in November to February (0.66-2 animals/10km). Likewise, birds were found dead on the road was maximum in August to October (5-6.33 animals/10km) whereas, minimum destruction was found in the months of December to February (1-2 animals/10km). On the other hand, Reptilian wild animal crushed on the roads were found highest in July to September (7-9 animals/10km) month of the year, whereas minimum number was found in the month of December to February (0-1.33 animals/10km), it may be due to the minimum activities of animals during the winter season. The data are documented in Table 4. Similarly, there were total number of wild animal killed in road accidents on the State highways showed two peaks, one low peak in the months of March-April and another high peak during August-September of the year. This was most probably due to their favorable condition for breeding and other activities (Figure 3).

DISCUSSION
The destruction rates of wild animals on state and national highways were found more or less similar. The seasonal variation in the number of wild animals hitting accidently by vehicles may vary due to the maximum and minimum activities and population variation of animals in different seasons. During our survey it was found that in the biodiversity rich area of Thar Desert few animals  and birds had been found most frequently killed in road accidents e.g. in Group Mammalia: Mongoose, Wild boars, Squirrel, Desert Fox, Chinkara were found most frequently killed. The reasons were different in each animal; in case of Mongoose they often cross the road in a patch of two to three members due to which they are vulnerable to road accidents, in case of wild boars they are often crush in the night due to the low sight and in case of Desert Fox and Chinkara they are vulnerable to accidents due to the sudden appearance before the vehicles, in case of the squirrel they became confused by speedy vehicles and often move back due to which they gripped by vehicles. In Group Reptilia: Desert Monitor and Sand Boa were killed most frequently in road accidents. The reasons were slow movement of these animals on the road and the bigotry attitude of humans about these animals due to which they intentionally crush them during road crossing. In Group Aves: Greater Coucal and Grey Francolin were found most frequently killed in road accident. The reasons are different in both; in case of Greater Coucal they often flew at lower site and often sudden dive on the roads from the flanking trees to cross the road while in case of Grey Francolin they often cross the road in line of one behind one hence are prone to accident. Apart From this many birds which have high and speedy flight were also found killed in road accidents e.g. Hawks, Sun bird, Ring Dove, Shrike etc. Besides this some of the rare and endangered animals were also found killed in road accidents in present study e.g. Jungle cat and Indian Grey Wolf which are the rare animals of the Thar Desert. Some of the glimpse of dead animals are shown in Plate 1 & 2.