Mr Sarkar's effort to save the World Heritage Site has been rewarded with the prestigious Hem Chand Mahindra Wildlife Foundation and Saevus Wildlife Warriors Awards 2013.
Despite the park being a very difficult area under siege of insurgents that make the condition of the staff working there severely challenging, Mr Sarkar served the Park for over 30 years at great personal risk, a top Assam Forest Department official in Manas said.
The pan India award, a tribute to the lesser known heroes in the forests, was presented at a function attended by several dignitaries at Ranthambore National Park on May 23, Manas Tiger Reserve Deputy Director Sonali Ghosh, IFS, said today.
Observing that there were many Park staff in Manas who served through the insurgency hit 1980s and 90s trying to protect its fast decimating wildlife, she said, recognition of the staff will go a long way in boosting their morale and motivating them to carry forward their good work.
Speaking about Mr Sarkar, Ghosh said he was earlier a small time hunter but was motivated to join as a game-watcher and serve wildlife by the then Park Director Srikantha Sharma.
Fondly called 'Sanil Sarkar' by his colleagues, he is a recruit of the classic old school forest management system whereby semi-literate young boys showing signs of courage were picked up by government officials to work in remote forest locations, she said.
Though Mr Sarkar does not remember his actual age, it is believed that as a young 14-year-old he impressed the Park Director when he swam the 22 km length of Beki river from Mathanguri to Bansbari in Manas area, Mr Ghosh added.
Since his enrolment as a game-watcher in 1986, Mr Sarkar has been an asset to the Park serving in difficult areas such as Kapurpora, Sidajhar, Rabang and now Bura Burijhar camps of Bansbari Range of MNP.
"Sunil is reticent about the days of insurgency, but he has served in various chowkis trying to protect wildlife - sometimes standing as a lone guard over his turf", Mr Ghosh said.
The wildlife, including elephants and sambars used to gather around the chowki (forest guard post), she said.
"The old timers used to give the animals salt from their rations and it was never sufficient. For months, he would have no communication with his family - that was the fate of most of the staff there - as communication systems failed", said the Deputy Director.
"Once the chowki he was in along with two other colleagues was burnt down by insurgents. He has faced militants and seen colleagues and park elephants being killed during his tenure", Mr Ghosh said.
The territory of the 950 sq km MNP in Barpeta district has very difficult areas as they are still under siege of militants causing the Environment Ministry report on tiger reserve to give the besieged areas special consideration, she said.
A part of Manas is still inaccessible due to armed insurgency - a school teacher was recently killed and kidnappings are routine, Mr Ghosh added.
"After initial glorious years under then Field Director Deb Roy, Manas through the late 1980s and the 90s was under siege by insurgents. All the Parks' rhinos were wiped out, elephants, tigers and other wildlife slaughtered ruthlessly", the Indian Forest Service official said.
The insurgency years saw the killing of six forest staff of various ranks, including a Ranger, and several domestic elephants besides, destruction of 28 camps and beats and two range offices, she said.
Manas has recovered now but continues to be very vulnerable to poaching and insurgency persists, she added.