Two tiger cubs and a tigress were found dead in two different forest ranges in the Nilgiris district late on Wednesday night and Thursday.
While the seven-year-old female tiger was found dead on a patta land in the Naduvattam range of forests, the two cubs were found dead in the Segur range of forests.
While cleaning the estate area falling under Mahaveer Plantations, workers found the carcass of the female tiger and informed forest officials.
"The tiger may have died a day ago," said Saravana Kumar, assistant conservator of forests, Nilgiris division.
"Injuries were found on the body of the tiger. Preliminary investigation suggested that the big cat could have died due to infighting," he added.
A postmortem was conducted by forest veterinarian Rajeshkumar in the presence of forest officials, representatives from NGOs and local bodies, as per the guidelines of the National Tiger Conservation Authority.