The endangered Bengal tiger could get a big boost from habitat upgrades.

A new study finds that improvements in the management of existing protected areas in South Asia could double the number of tigers currently existing in the region. The small improvements, detailed in a recent issue of the journal Biological Conservation, include better funding, increasing staff support, restoring tiger habitat, and stepping up enforcement activities that focus on preventing the poaching of tigers and their prey.

The researchers, including scientists from the Wildlife Conservation Society and other institutions, examined 157 reserves throughout the Indian subcontinent, which includes India, Bangladesh, Bhutan and Nepal. They found 21 of the protected areas, concentrated in a few regions in central India, and the Indian borders with Nepal and Bhutan, meet the criteria needed for large healthy tiger populations. Eighteen of the 21 areas currently contain Bengal tiger (Panthera tigris tigris) populations.

"We were happy to find that the most important reserves identified in the study already have made tiger conservation a priority," said the lead author Jai Ranganathan of the National Center for Ecological Analysis and Synthesis in California.

All together, the 21 protected areas have the capacity to support between 58 percent and 95 percent of the subcontinent’s potential tiger capacity, estimated to be between 3,500 to 6,500 tigers. Current estimates put the population of tigers somewhere between 1,500 and 4,000 animals in the four countries combined.

The remaining 129 protected areas do not have the potential to sustain high numbers of tigers, but nonetheless these reserves could be capable of containing tigers over the long term if the landscape surrounding the reserves are better managed to reduce negative impacts.

The tiger is endangered in all of its natural habitats, a range stretching from India down into Southeast Asia as far as the island of Sumatra, and in the Russian Far East, and is listed as endangered in the United States and internationally.

Though no truly accurate global numbers exist, conservationists estimate that 5,000 tigers remain in the wild. About 150 years ago, 100,000 tigers may have roamed throughout much of Asia, according to some estimates.