During a survey conducted in 2010, only 130 bisons were spotted in the core area of the Trishna sanctuary spread over more than 164 sq km. But this year the number has risen to 145, a forest official said.
The 30 sq km Bison reserve was established in Trishna sanctuary a few years ago with funds from the Centre to preserve and protect the endangered species of Bison, locally known as Gaba or Gaur, he said.
Grass has been cultivated in major habitats of bison in the Trishna core area as well as the National Park area, the official said.
Recently plantation of one species of Bamboo, locally known as Kaillai, which is a favourite food of Bison has been started to meet the need of food during the lean period, the official said.