Global warming is putting the pika, a hamster-like mammal, in peril. High in the Colorado mountains, a National Geographic researcher is trying to find out why its numbers are falling. Video.

Over the past 30 years key species have declined by 40 percent both inside and outside the reserves, according to a new study that questions a central tenet of Kenya's wildlife conservation strategy.

See undersea worlds that stand to be lost—and that six Southeast Asian governments are trying to save with their new Coral Triangle initiative to protect coastal reefs. Video.

A new study finds that people naturally walk in circles when their sense of direction is lost. Researchers had people walk in the desert and through a forest. Video.

The recently explored Son Doong cave, filled with poisonous centipedes and towering stalagmites, beats out the previous world-record holder for the largest single cave passage ever found, British explorers report.

Stretching more than 2.7 miles long and soaring as high as 460 feet, a cavern in Southeast Asia is the biggest single cave passage yet found, British explorers say.

A favorite of divers in Australia, the blue groper grows to about three feet (one meter) long and can change its own sex. But its numbers are diving, and researchers are trying to throw the groper a lifeline. Video.

In the first goring death at Spain's running of the bulls since 1995, a 27-year-old was killed Friday after a bull became separated from the pack. Video.

Two years after most of Russia's geysers were lost in a landslide, a peculiar geyser has emerged on the Kamchatka Peninsula that spouts water every 6 to 20 minutes.Video.

About two thousand people took to the streets of Pamplona for the first of eight bull runs, finishing the course in a quick two-and-a-half minutes.Video.

Despite falling nearly ten stories from it and losing a child in 2008, the Combatas—like the other seven families of a Bolivian village—continue using a crucial river-spanning cable. Video.

In a Florida forest, worm "grunters" use an unusual technique to catch earthworms to sell for bait.Video.

A bug-eyed salamander and a colorful poison frog are among 12 species possibly new to science recently found in the mountains of Ecuador. Video.

To stimulate summer vacations at national parks, the U.S. National Park Service is waiving fees at 147 destinations on three weekends this summer.

The Air France crash investigation is now focused on the intertropical convergence zone, where trade winds converge, spurring giant storm clouds that can be tough to navigate, experts say.