The bears have been radio-collared and are orphans. They were raised by wildlife experts from International Fund for Animal Welfare (IFAW), its partner the Wildlife Trust of India (WTI) and the Assam Forest Department.
"Unlike in the initial stages of their rehabilitation, the bears havent returned to the acclimatisation camp. We have been tracking them with the help of radio-collars fitted on their necks," said Bhaskar Choudhury, IFAW-WTI veterinarian in-charge of the project.
The bears, which are an endangered species, were rescued last year by the Assam Forest Department from local people who had kept them as pets.
Barely a few months old when they were rescued, the bear cubs were handed over to the lower Assam unit of IFAW-WTI Mobile Veterinary Services (MVS) at Kokrajhar for hand-raising and eventual rehabilitation.
In mid 2008, the bears were relocated to the release site in Doimari range, Manas National Park, near the Indo-Bhutan border, for a programme specifically termed "assisted release".