Date Published: April 10, 2019
Publisher: Public Library of Science
Author(s): Lalit Kumar Sharma, Tanoy Mukherjee, Phakir Chandra Saren, Kailash Chandra, Govindhaswamy Umapathy.
Different Biogeographic provinces and environmental factors are known to influence the dispersibility of long-ranging carnivores over the landscape. However, lack of empirical data on long-ranging carnivores may lead to erroneous decisions in formulating management plans. The Indian Grey wolf (Canis lupus pallipes) is known to be distributed in the vast areas of the Indian subcontinent. However, the actual population estimates are available only for Gujarat, Karnataka, Rajasthan and Bihar. Whereas, its distribution, population and habitat ecology is poorly known from the eastern region. Hence, this article aimed to evaluate the habitat suitability along with landscape connectivity for the species over the two major biogeographic provinces of India, i.e., Lower Gangetic Plains (7b) and Chhota Nagpur Plateau (6b). The present model with significantly higher Area under the curve (AUC) value of 0.981, indicates its accuracy in predicting the suitable habitats and identifying biological corridors by using environmental, topological and anthropogenic variables. Precipitation of the driest quarter and the precipitation of seasonality were the two best performing variables in our model, capable of explaining about 26% and 22.4% variation in the data respectively. Out of the total area i.e. 4,16,665 Km2, about 18,237 Km2 (4.37%) was found to be highly suitable area and about 3,16,803 Km2 (76.03%) areas as least suitable. The corridor analysis indicated that the habitat connectivity was highest in the border line area of the two biotic provinces located in the south-eastern zone via districts of Purba Singhbhum and Paschim Singhbhum of Jharkhand state and Bankura and West Midnapore districts of West Bengal state. Among the Protected Areas (PAs), natural corridors exist connecting the Simlipal National Park (NP)-Satkosia Wildlife Santuray (WLS), Dalma ranges of Chotta Nagpur plateau along with Badrama WLS, Khulasuni WLS and Debrigarh WLS. Differential management through landscape level planning may be helpful in securing the future of the species in the landscape.
India is home to two subspecies of the wolf, i.e. Tibetan Wolf (Canis lupus chanco, Gray, 1863), and Indian Grey Wolf (Canis lupus pallipes Sykes, 1831) [1,2]. The Tibetan Wolf is distributed in the Himalayan landscape in the elevation range of 3000–4000 m with sub-alpine and alpine conditions. On the contrary, the Indian Grey Wolf is one of the top carnivores in the much of the plans and peninsular region of the country with the varied type of habitats with warm and dry conditions, it occupies grassland, scrublands of semi-arid regions and agro-forestry landscape [3,4,5]. It has been stated that the primary factor behind the establishment of its niche in semi-arid and arid conditions is evolution during the dry period of the Pleistocene . Among the two sub-species, the Indian Grey Wolf is more abundant and presently distributed in isolated grassland ecosystems of Rajasthan in West to West Bengal in East, and from Haryana in North to Karnataka in southern region of the country . Whereas, the Tibetian Wolf is relatively less in number with very confined distribution in the relatively narrow niche in the higher himalayas.
The present study was conducted in two biogeographic provinces namely Chotta Nagpur plateau (CNP) (6b) and Lower Gangetic planes (LGP) (7b) covering much of the Indian Grey Wolf eastern range. These two biotic provinces are part of the Deccan peninsula and Gangetic planes bio-geographic zones respectively, and their classification in based on climatic conduction, soil as well as uniqueness in biodiversity  (Fig 1). The LGP cover most of the Bihar, whole of the West Bengal (excluding the Purulia district and the mountain-ous parts of Darjeeling district), eastern region of Orissa and north-eastern portion of Jharkhand States of India. Whereas, the CNP forms the north-eastern edge of the Indian peninsula and the entire plateau can be subdivided into several small plateaux or sub plateaux. It embraces the districts of four states: Bihar, West Bengal, Madhya Pradesh, and Orissa. The study landscape together (CNP and LGP) holds a large network of Protected Areas viz., six National Parks and 36 wildlife sanctuaries which in totality account for about 3.47% (14,476.61 Km2) of the total area of Chotta Nagpur Plateau and Lower Gangetic Plains . The entire landscape is almost featureless plain except for few mountainous ranges of Malda-West Dinajpur tract, Chotanagpur plateau, and duars of Jalpaiguri (S2 Fig). The mean temperature ranges from 23–380 C with average annual rainfall of 100–150 cm. The vegetation is broadly characterised by dry deciduous forests, tropical and subtropical dry broadleaf forests . The dominated land use type in both the biotic province is agriculture, constituting about 62.10% and 79.23% in CNP and LGP respectively followed by settlements, orchards and water bodies. Increased agricultural and other anthropogenic pressure results in fragmentation and increased disturbance in both the provinces. Recent trends in disturbance profiles also indicating impact of anthropogenic pressure, around 29.11% in CNP and 32.77% in LGP of the total vegetated areas are categorised to be in highest disturbance state . Moreover among the vegetated areas the highly fragmented forest area have increased to about 3.33% and 8.07% in CNP and LGP respectively . The other most prominent large mammalian species present in the study landscape includes viz., Panthera tigris, Elephas maximus, Tetracerus quadricornis, Antilope cervicapra, Cuon alpinus and Melursus ursinus.
A total of n = 126 spatially independent presence locations of the Indian Grey Wolf were recorded during two field surveys carried out in the year 2015–16. Out of which n = 32 presence locations were collected from the questionnaire surveys and secondary sources, i.e., old records of Zoological Survey of India, Kolkata, interview forest staff and GBIF database. A total of 360 ground truth points were used for accuracy assessment equally divided in to forest cover classes. The overall accuracy and the Kappa coefficient of the classified forest cover image was found to be 88.61% and 86.30% respectively where SE of kappa was 0.020 (S1 Table) (S1 Fig).
The Indian grey wolf is one of the top carnivore species distributed in the open grasslands of peninsular India. Till date, much of the studies on the species have been conducted in its western and southern ranges, whereas, no reliable information is available in its eastern range except a short study by . Furthermore, no attempt has been made to map its eastern range which is pro-vital for its conservation and management planning. The Indian grey wolf is threatened throughout its range due to its involvement in livestock depredation. The large tract of semi-arid eco-region is largely rainfed where the agriculture is mostly animal dependent and the economy of the local communities is based on animal husbandry. The increase in livestock depredation incidences by wolves is leading to the development of antagonistic behaviour among the locals towards the species which will be detrimental for its long-term survival [20, 58]. Hence, through the present model, we identified and mapped the habitats suitable for the species and much of the highly suitable habitats are falling in areas compost of dry scrub vegetation, open forest and agroforestry landscape . The higher AUC value of 0.981 indicates that the selected variables in the present model were very good predictors of mapping suitable habitat of the species (S3 Fig). The negative association of the precipitation of the driest quarter and seasonality indicates that the suitable habitats for the species are located in areas with relatively drier conditions with the low amount of precipitation. The present results corroborate with the findings of the other studies highlighting that the wolf is a top carnivore reported to be distributed in areas with hot and semi-dry environmental conditions [3, 4, 5, 10].
Although the two biotic provinces Chotta Nagpur Plateau and Lower Gangetic Plans represents two bio-geographic zones, i.e. Gangatic plans and Deccan Plateau but the border areas of these two provinces possess noteworthy commonality in terms of faunal species composition, topography, and climate as well as forest types. The present study has highlighted that the border area of the two provinces provides habitat which is supporting the remnant population of wolves in this landscape. The study could be also able to map the possible biological corridors through which the species may be using as movement corridors and utilizing the habitats.