The Signals From Vidharba's Tigers
A research study with 15 radio-collared tigers shows how big cats use human-dominated landscapes.
Records kept tumbling between December 2019 and March 2020, when a sub-adult male tiger made new strides every day in Vidharba, the north-eastern region of Maharashtra. At the turn of the year, the striped cat had crossed the 1500 km mark. This was the longest walk or movement of a tiger recorded in the country. By the end of February, the cat had clocked over 2000 km moving across six districts and four wildlife sanctuaries.
For 396 days, (February 27, 2019 – March 28, 2020), scientists from the Wildlife Institute of India (WII) and Maharashtra Forest Department tracked and monitored the tiger’s movement by using a GPS fitted radio-collar on the animal. Born in Tipeshwar Wildlife Sanctuary, Yavatmal, in 2016, the big cat was radio-collared on February 27 by Bilal Habib and Parag Nigam, two senior wildlife scientists from WII.
Codenamed ‘Walker / T1C1’, the tiger moved out of Tipeshwar in June. Another dominant male most probably forced him out for lack of space. Tigers are solitary animals and each individual needs his or her own territory.
‘Walker’ became an internet sensation when several Indian forest officers began to post his record-breaking movements on social media. He was moving through canals, agricultural fields, villages, forests, industrial areas and roads. For months, the scientist on their toes could read through the GPS signals transmitted from the radio-collar that the cat was resting during day and walking at night, all for finding a suitable habitat and partner. More importantly as the tiger settled in Dnyanganga Wildlife Sanctuary, around 200 km from Tipeshwar as the crow flies, the cat did not get into any major conflict with humans except for isolated instances of cattle kills that made villagers jittery over a tiger in their backyard.
While ‘Walker’ hogged all the limelight, Habib, Nigam and the WII team were simultaneously tracking 14 other tigers in the same Vidharba landscape. Since 2015, WII was leading a long-term scientific study to understand how tigers disperse in Vidharbha, the north-eastern region of Maharashtra. This was also the first long-term study in India to delineate tiger corridors based on actual movement data of tigers by the Maharashtra Forest Department in collaboration with WII.
The study, Telemetry Based Tiger Corridors Of Vidharbha Landscape, Maharashtra, India, which came into the public domain in the last week of May states, “The Vidarbha Landscape is very important as it harbours a population of about 331 tigers and forms the connecting link between the central and southern Indian tiger populations. It plays a pivotal role in the exchange of individuals and thereby facilitates gene flow between these two populations increasing the viability of tiger populations in India. There are eight protected areas or wildlife divisions where these tigers live, but these refuges are scattered like islands in a sea of human-dominated landscape. Therefore, knowing the locations of tiger movement corridors and probable areas of human-tiger conflict is especially important for a wildlife manager.”
According to WII scientists, most Tiger Reserves are isolated patches of forest in a sea of human-dominated landscapes. In such a scenario, habitat connectivity is extremely essential to prevent species extinction by isolation of population and or restriction of gene flow. Habitat loss and fragmentation have been recognized as a key issue in wildlife conservation. In the face of habitat fragmentation, persistence of wildlife populations depends, at least in part, on their ability to move through these human-modified landscapes. The study categorically states that tiger conservation in India solely depends on the identification of such dispersal corridors and on mitigation of conflicts with humans along these contested spaces.
Three studies in tiger genetics published in 2017 draw alarming connections between the demolition of forest corridors and its effect on the reproductive progression of the big cat. If current trends of deforestation continue, then inbreeding, diseases and the lack of genetic variations will push the species towards extinction.
Lest we forget, on the night of 29 December, 2017, the large male tiger Bajirao was run over by a speeding vehicle on National Highway 6 near Bajargaon, close to Nagpur. Bajirao, a favourite among tourists, was the dominant male tiger from Bor Tiger Reserve, India’s smallest tiger reserve, with an estimated population of 10-12 tigers. Incidentally, Bor’s “critical tiger habitat" of 138 sq. km is smaller than Bajirao’s home range—a 150 sq. km area that spans swathes of forest and human-dominated land in the districts of Wardha and Nagpur. According to tourist safari guides, Bajirao was an infrequent visitor to Bor. That night, the tiger seems to have run out of luck outside the protective cover of the reserve. The high beams of passing vehicles probably blinded it.
Bajirao, Walker and other tigers in the study are among around one thousand tigers (35 per cent of India’s tiger population), which reside (most of the time) outside the confines of wildlife sanctuaries and tiger reserves. They are our ‘poor tigers’ as one high-ranking official put it, vulnerable to poaching or susceptible to conflict with humans. A point often missed in the fine print when celebrating India's tiger numbers once in every four years.
“Our study shows a high probability, as much as 56%, for tigers to go locally extinct from small reserves like Bor if the current population gets isolated from other reserves. Tigers need to remain connected with other subpopulations to maintain a healthy genetic variability. As the median number of tigers within most reserves are low for a viable population interlinking, forest corridors are vital for the future of tigers," says wildlife biologist Prachi Thatte, author of ‘Maintaining Tiger Connectivity And Minimizing Extinction Into The Next Century: Insights From Landscape Genetics And Spatially-explicit Simulations,’ published in 2017.
This new WII study puts the spotlight firmly back on India’s ‘poor tigers’ and how they are using a much wider swathe of the landscape outside wildlife sanctuaries for movement than earlier known. The extensive use of farmlands for movement is pushing their luck with human tolerance. It is to be seen how management interventions on these wildlife corridors secure their future. It will be also important to see how many other tiger states follow Maharashtra's example in identifying interlinking animal corridors to secure the tiger's future.
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