Isolated Tigers

http://animalzoon.blogspot.in/

The tiger Shere Khan was lord in Rudyard Kipling's Jungle Book, but his modern-day descendants are king no more: The big cats have seen their central Indian forests dwindle and fracture.

The remaining tigers are only surviving by moving through critical—but unprotected—corridors of land that link distant populations, a new study says.

Using hair and fecal samples, Sandeep Sharma, of the Smithsonian Conservation Biology Institute, and team studied genes from 273 individual tigers that live in four distinct locations within India's 17,375-square-mile (45,000-square-kilometer) Satpura-Maikal region.

Tigers once roamed across Asia from Turkey to the Russian Far East, but have vanished from over 93 percent of that range. (See tiger pictures.)

The 20th century was especially tough on the now-endangered beasts, when three subspecies became extinct, leaving six—all of which are at risk. (See a National Geographic magazine interactive of big cats in danger.)

At a glance the region's tigers seem to live in four populations, each occupying its own territory in what's called a designated tiger conservation landscape, or TCL. Those are Kanha-Phen, Pachmari-Satpura-Bori, Melghat, and Pench.

But the genetic study suggests otherwise: Corridors of woods and undeveloped land up to 125 miles (200 kilometers) long actually link Kanha and Pench into a single genetic unit, and Satpura-Melghat into a second.

That means the four populations of tigers are breeding as two much larger populations—and keeping their genetic diversity alive in the process.

Corridors also aid tiger survival on the ground, Sharma said, making the cats more likely to withstand many types of threats. (Related:"Tigers Making a Comeback in Parts of Asia.")