Valmik Thapar, a tenacious conservationist who wrote eloquently about tigers in India and worked to protect them against the impact of poachers, the loss of habitat and government policies that he abhorred, died on May 31 at his home in New Delhi. He was 72 or 73.

His family said in a statement that the cause was cancer. He was born in 1952, though the specific date is unclear.

Mr. Thapar was a big man with a loud, hyperarticulate and uncompromising style, which he channeled in service of tigers. He believed that they deserved nothing less than “inviolate protected areas” in which to live without human encroachment.

“He was not an institutional person, but he was an institution unto himself because of his knowledge, sensitivity and ability to communicate,” Ravi Singh, the chief executive and secretary general of the World Wildlife Fund-India, said in an interview.

Ullas Karanth, the former India program director of the Wildlife Conservation Society, which operates four zoos and an aquarium in New York City, said in email that Mr. Thapar had “used his deep political and media connections to widely publicize the ‘tiger crisis.’”

The tiger population in India, home to most of the world’s wild tigers, fell from about 40,000 in the 1950s to 1,411 in 2006. But conservation efforts have led to its substantial growth, to 3,682 in 2022. In the Ranthambhore Tiger Reserve, in the northwestern state of Rajasthan, where Mr. Thapar first fell in love with the animals, the number rose from about 15 in 2006 to about 70 in 2022, Mr. Singh said.

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