As 60 Minutes Wednesday reported a year ago, these creatures are threatened by, among other things, poachers, who sell rhino horns on the black market. Logan went on elephant-back with conservationists in search of the rhinos.
The great one-horned rhinos are 15-foot-long behemoths with a pre-historic pedigree. They're fast, strong and have razor-sharp teeth.
"At which point can the one-horned rhinoceros be taken off the endangered species list?" asks Logan.
"Well, I'd like to say within my lifetime. But I think it's gonna require, if not eternal vigilance, at least for the next 50 years," says biologist Eric Dinerstein of the World Wildlife Fund.
And he just might be right. A new official rhino census, the first in five years, shows that Nepal has lost nearly a third of its 600 rhinos. It's easier for poachers to kill them, because the Nepalese government has shifted soldiers who used to protect the rhinos to a new job: fighting a growing Maoist insurgency.
Broadcast: April 21, 2004
Scientists have named them "Rhinoceros Unicornis," an extraordinarily rare species of rhino that has a single horn, like the mythical unicorns.
These pre-historic creatures can be found in a remote corner of Nepal, the inspiration for the fictional paradise of Shangri-La.
But the existence of these rhinos is in danger for two reasons. First, because poachers wants the rhino's horn, which is worth a small fortune on the black market. And second, because humans have been taking over their natural habitat, the primeval jungles of southern Nepal.
Only a few hundred of these ancient mammals survive today. And, as Correspondent Lara Logan reports, getting to them required a trek into a land that time forgot.
The rhinos live in the grasslands and rivers of Nepal's Chitwan National Park, and the safest way to get close to the two-ton beasts is on the back of an even bigger animal: an elephant.
More than a dozen highly trained elephants were waiting for us at the base camp, deep inside the park.
There, we joined up with the scientists and park rangers whose mission is to save the rhinos by learning more about how they live. They hunt them down, and then shoot them with special darts filled with a powerful tranquilizer.
Our hunting party was lead by Dr. Tirtha Maskey, director of Nepal's national parks. He has worked for 30 years to save rhinos from extinction.
Our first challenge was figuring out how to climb aboard the elephants. Biologist Eric Dinerstein gave us a quick lesson, and he's been doing this since he first came to Nepal in 1975 to study rhinos. Cameraman Dennis O'Keefe rode the elephant just ahead of us, as our caravan headed off into the bush.
Earlier this morning, Nepalese trackers were out on elephants and spotted two rhinos about a half-mile away. So that's where we're going -- into the world's tallest grassland, through a small patch of forest along the river. We hope to find the rhinos on the other side.
These rhinos live in the lowlands of Chitwan Park, which is 75 miles southwest of Kathmandu, on Nepal's border with India. The great one-horned rhinos are 15-foot-long behemoths with a pre-historic pedigree. They're fast, strong, and have razor-sharp teeth. And for 35 million years, they've lived in a primeval jungle alongside hundreds of other wild creatures.