National

Biologist George Schaller is the first to survey wildlife in Tibet's remote Chang Tang reserve in the winter. Schaller spoke with Alex Chadwick about some surprising findings from his 1,000-mile journey.

Snow leopards are among the world's most endangered big cats, with only several thousand left. In Mongolia's southern Gobi desert, the snow leopard is a sign of a healthy ecosytem. But poaching remains one of the area's more lucrative businesses.

Snow leopards are among the world's most endangered big cats, with only several thousand left. In Mongolia's southern Gobi desert, the snow leopard is a sign of a healthy ecosytem. But poaching remains one of the area's more lucrative businesses.

A settlement once home to hundreds has been unearthed near England's Stonehenge. Archaeologists think the builders of the huge stone circle may have lived in the village. It dates to the same time period.

A settlement once home to hundreds has been unearthed near England's Stonehenge. Archaeologists think the builders of the huge stone circle may have lived in the village. It dates to the same time period.

The Asian tsunami of 2004 killed more than 170,000 people in the Indonesian province of Aceh alone, washing away tens of thousands of homes, schools and businesses. Two years later, reconstruction is under way, but serious challenges in housing and infrastructure remain.

The Asian tsunami of 2004 killed more than 170,000 people in the Indonesian province of Aceh alone, washing away tens of thousands of homes, schools and businesses. Two years later, reconstruction is under way, but serious challenges in housing and infrastructure remain.

It took them two years, but Colin Angus and Julie Wafaei are the first people to circumnavigate the globe completely by self-propulsion. That means they rowed across the Atlantic -- no sails. And biked and hiked across Siberia.

It took them two years, but Colin Angus and Julie Wafaei are the first people to circumnavigate the globe completely by self-propulsion. That means they rowed across the Atlantic -- no sails. And biked and hiked across Siberia.

In literature, albatrosses represent weighty, inescapable burdens. But in real life, the huge seabirds use wind energy to cruise around the planet's oceans. Photographer Frans Lanting and writer Carl Safina report from one of the world's largest albatross colonies.