New Delhi, April 13, After waiting for 27 long years, India has finally got a sedating drug, and used it to rehabilitate four single-horned rhinos, paving the way for conservation of one of the most endangered species, found only in India and Nepal.

On Friday, in a historic conservation effort, foresters at Dudhwa National Park, Uttar Pradesh, successfully rehabilitated the rhinos for the second time here.

Officials, with the help of volunteers of WWF and Wildlife Trust of India (WTI), rehabilitated three female and one male rhino in a 13.5 sq km enclosed area of in the forest's Belraya Range, some 15 km from the present 24 sq km Sonaripur Range enclosure, where 34 adult rhinos thrive.

The rehabilitation programme was stuck since 1991, due to want of a sedating drug which is banned in India. The key drug -- M99 -- is used to immobilise large animals like rhinos.

"It was a very long wait, but we had to take some bold decisions as to ensure it was not delayed any more. This is historic event and key to conservation of Indian rhinos," Dudhwa National Park Director Sunil Choudhary told IANS on the phone.

The drug was important because rhinos, as a routine, are not tranquilised since they cannot be left in that state for longer than 60 minutes, Chaudhary added.

"We finally got the drug. We imported it from South Africa earlier this year and had been gearing up for this days since then," Mahaveer Kaujalagi, Deputy Director, Dudhwa National Park told IANS on the phone.

He added that the male rhino, aged around 10, and the three females aged 9 to 13 were carefully selected and have good breeding potential.

For monitoring purposes, an elephant squad consisting two elephants and seven to eight volunteers has been permanently stationed in the new enclosure has been ringed by solar-powered fencing, an official said.

The state forest department, in December 2016, had informed IANS that it sought to obtain a no-objection certificate (NOC) from the central government to acquire -- Etorphine (M99) and its antidote -- a drug produced in some African countries.

"The replication of the first rehabilitation case of Dudhwa was very important. Since there was no drug, we prepared everything at the backend including installation of the solar fensing in the area,"Koujalagi said, adding, "I am so excited that I am part of this historic event."

Considered one of the most successful rehabilitation programmes in India, rhinos were re-introduced in Dudhwa in 1985 after the region was stripped off its last free-ranging rhino by a hunting party in 1878.

There are around 2,768 rhinos in India, of which 2,505 are in Assam, as of 2016.

Abode to a highly diverse ecosystem at the heart of Terai region bordering Nepal, Dudhwa has several endangered animals, including tigers, elephants, Indian rhino, leopard, barasingha (swamp deer), sloth bear and others.

(Kushagra Dixit can be reached at