By Laura Zuckerman
SALMON, Idaho (Reuters) - Yellowstone National Park rangers are investigating whether a grizzly bear killed a hiker whose body was found Friday on a popular park trail, officials said on Saturday.
The hiker was identified as a 60-year-old man from Michigan's Upper Peninsula, but his name was being withheld pending notification of family members.
Yellowstone spokesman Al Nash said rangers reported finding signs of grizzly activity at the scene. But he added that an autopsy would likely reveal whether the man was the victim of an animal attack, another kind of accident or died of natural causes.
Rangers have not ruled out that the man's remains may have been scavenged by bears after he perished by some other means.
"Bears are opportunistic eaters, so they will utilize almost any food source they may come upon," he said.
It was not immediately clear if there were signs of a struggle at the scene.
"There are still several unanswered questions," Nash said.
As a precaution, park officials shut down the trail where a pair of hikers found the body on Friday afternoon. A path north of the site and sections of another hiking route, all areas favored by grizzlies, also were closed for safety reasons.
Aerial surveys on Saturday revealed no sign of grizzlies in the vicinity, Nash said, adding the park had received no reports of aggressive animals on those trails in recent days.
In July, a female grizzly in Yellowstone attacked and killed a hiker it perceived as a threat to its two cubs. It was the first fatal bear mauling at the park since 1986.
Bear managers opted not to capture or kill that grizzly because it had been acting in a purely defensive -- as opposed to predatory -- manner and had no previous history of conflicts with humans.
But the park euthanized a 4-year-old male grizzly early this month after the 258-pound animal charged a man sitting on a hiking trail near Yellowstone Lake.
It was the last of a string of incidents in which that bear showed aggression toward people in its search for food at campgrounds and other developed areas, officials said.
The greater Yellowstone region, spanning parts of Wyoming, Idaho and Montana, is home to at least 600 grizzlies -- outsized, hump-shouldered bears protected under the U.S. Endangered Species Act.
(Editing by Steve Gorman and Peter Bohan)