The Uttarakhand park is home to about 200 of India’s 1,700-odd tigers and nine have died so far in the reserve over the past year, officials said.

The state government has sought the Wildlife Crime Control Bureau’s help to carry out an exhaustive probe. WCCB deputy director Nishant Verma and assistant director R.S. Thakur are leading the team that arrived from Delhi.

Speaking on the recent deaths, park officials said the first carcass — of a female tiger aged about two years — was found on May 27 near a canal in the reserve’s Dhela range.

The second carcass, of a male tiger about one-and-a-half years old, was found on May 29 in the Ampokhra range under the Terai west forest division.

The third carcass of a tiger, which may have died 10 days ago, was found in the Fato range of the Terai west division on June 1. This tiger, too, was a male, about two-and-a-half years old.

Corbett field director Samir Sinha, who said he suspected poachers were behind the recent deaths, has ordered patrolling to be stepped up in and around the park.

Officials said poachers might have poisoned the watering holes where the tigers come to drink. Saket Badola, the park’s deputy director, said the water bodies were being checked for traces of poison.

Wildlife officials have taken four Gujjar men into custody in connection with the recent tiger deaths but have got no leads from the forest dwellers yet.

The WCCB team visited parts of the western Terai fringe bordering Thela river and inspected the area where the last carcass was found. “We inspected the area and the bureau has activated its own network of informers to find out if these were acts of poachers. We hope to make a breakthrough soon,” Verma told reporters in Corbett.

The Opposition BJP has sought a full-time minister for the environment and forest department, now being handled by chief minister Vijay Bahuguna.

In Dehradun, Anil Baluni, the BJP state unit spokesperson and former vice-chairperson of the state forest and environment advisory committee, said the national park had “virtually become a graveyard” for tigers.

“We need to stop the menace of poaching and it requires a political will to do so. But the state government appears to be just too casual about it,” he said.

Sunita Chauhan, a wildlife activist in Nainital, said she was shocked that the “tragedy” of tiger deaths was “being repeated” at the Corbett national park, the country’s oldest. “Can’t anything be done?” she said. “Can’t vigil be stepped up?”