(Airs Sunday, March 7) Around the globe, unique and fascinating species face extinction. Follow the plight of these creatures and the dedicated conservationists who fight for them.

For some of the loneliest animals on the planet, captive breeding programs and human intervention may the only hope.

For decades, Hardy Jones has been working to expose and stop the trade in dolphins used for food and entertainment. In some cases, Jones's footage has helped stop dolphin captures.

In 1956, the Columbus Zoo in Ohio became the home of the first gorilla to be born and raised in captivity.

While Snowflake may be gone, his legacy remains. In his time at the zoo, he fathered 21 gorillas, who have in turn given birth to 10 grandchildren, says Carme Mate, a primatologist in Barcelona who observed Snowflake for years.

For nearly 40 years an albino gorilla named Snowflake was adored by people around the world.

Carol Buckley spent more than 20 years performing with her elephant, Tarra, in zoos and circuses before deciding the animals deserved a different life.

On the streets of Bangkok and other large cities in Thailand, unemployed and homeless Asian elephants are becoming a common -- and controversial -- sight.

As early as 1796, traders began shipping Asian elephants to Europe and North America. By the 19th century, Asian elephants were a staple of zoos and traveling circuses.

NATURE explores the unusual problems created as the struggle to give Asian elephants a home is fought worldwide.