See what towns made the list of the world's dirtiest cities, and witness the grim toll that pollution is taking on people and the environment from Peru to China.
Images of the elusive Chinese mountain cat might help experts better understand the animal while increasing public awareness of its plight, researchers say.
A female shorebird was recently found to have flown 7,145 miles (11,500 kilometers) nonstop from Alaska to New Zealand, without taking a break for food or drink.
Salmon surrogates have created young that are 100 percent trout, researchers say. The technique could be used to produce species that are endangered or even extinct.
Tiger paw prints found in unprotected forests in western India suggest the animals are reclaiming their old territory, but some experts doubt the evidence.
Two-thirds of the world's polar bears will vanish in less than five decades as sea ice melts due to a warming climate, a suite of U.S. government studies concludes.
The Mekong catfish travels more than 600 miles (1,000 kilometers) upriver to spawn—a discovery that means a planned dam on the river might spell disaster for the species.
