yellowstone national park

BILLINGS, Mon. - The return of grey wolves has dramatically altered the landscape in portions of Yellowstone National Park, as new trees take root in areas where the predators have curbed the size of foraging elk herds, according to scientists in a new study.

State wildlife officials say they plan to allow bison back into the Gardiner Basin north of Yellowstone National Park this winter.

In this Feb. 14, 2011 photo, a government horseback rider hazes bison to move them from one location to another, just inside Yellowstone National Park near Gardiner, Mont.

Authorities were investigating whether a grizzly bear found dead outside Yellowstone National Park was killed illegally, they said on Tuesday.

A grizzly bear that fatally mauled a hiker in Yellowstone National Park was killed after DNA evidence linked the animal to the scene of a second hiker's death a month later, a park official said Monday.

A hiker killed by a mother grizzly bear this summer in Yellowstone National Park may have unwittingly helped provoke the attack by running from the animal, a report released on Tuesday said.

A man calling 911 from Yellowstone National Park can be heard telling rangers that he believes a grizzly bear is attacking a hiker and he can hear the man screaming for help.

A Yellowstone National Park spokesman says two more grizzly bears have been captured as part of an investigation into last month's mauling death of a Michigan man.

The Michigan man found dead last week, killed by a grizzly bear while hiking through Yellowstone National Park, died while visiting a place he loved, his family told ABC News.

Investigators have been searching a swath of Yellowstone National Park by air and foot as they try to determine whether a man whose body was found on a backcountry trail was the victim of a grizzly bear attack.