A dead swan pulled from a Scottish harbor has tested positive for the deadly H5N1 strain of avian influenza. Experts stress that birds, not humans, are at risk.

Scientists have found that umbilical cord blood may be a new source of organ-growing stem cells. But experts disagree about the future of this potentially life-saving resource.

Caribbean coral reefs weakened by bleaching are now dying from disease at an alarming rate, according to scientists who monitor the ocean ecosystems.

In a medical first, doctors create working bladders from patients' own cells and successfully implant them in children and teens.

In eastern Antarctica seabirds such as Adélie penguins are giving birth later, because shrinking sea ice is diminishing their food supply, scientists say.

Scientists say the U.S. is prepared for a slow-growing flu virus in the event of an oubreak, but perhaps not one that spreads more quickly. Also: news on a preliminary bird-blu vaccine.

A proposal to erect 700 miles of immigrant-stopping fence along the U.S.-Mexico border could pose disastrous threats to endangered wildlife.

A deep-seated reason for hope? In the lowest reaches of the sea, out of reach of fishing fleets, creatures are actually increasing in number.

The Bush Administration has announced new fuel economy standards for SUVs that it says will save millions of gallons of gas a year. But some observers say that's just a drop in the bucket.

The air over Antarctica has warmed dramatically over the past 30 years, according to a new study—so dramatically that scientists are hard pressed to explain the spike in temperature.

Approach of the Category Four storm—the nation's second major cyclone in ten days—prompted evacuations and suspension of mining and energy operations.

The South Pacific nation of Kiribati has designated an enormous swath of atolls, coral reefs, and deep ocean to become the world's third-largest marine reserve.

Despite common perceptions of England as a grey and damp destination, the island nation may be facing one of the worst droughts in a century, experts say.

"Car-free day" events in cities across the U.S. are giving urban dwellers a taste of life with fewer—and in some cases no—cars.

Global warming strikes again? Snowmelt is swelling rivers earlier and earlier, scientists say. The premature gush could cause havoc for reservoirs and animals.