(REUTERS) - A man who suffered a heart attack and died outside his rural Northern California home had his corpse dragged away and eaten by a black bear that was sheltering nearby, medical officials said on Friday.

The 65-year-old man, identified as Marion Williams, had walked from his trailer in Humboldt County to a water source about 91m away on October 8 when he suffered cardiac arrest, said Humboldt County Deputy Coroner Roy Horton.

A bear that was bedding just metres from the water source apparently saw or smelled the body and dragged Williams away, he said.

"The bear saw the opportunity for a food source and took advantage of it," Horton said, adding that the bear stripped Williams out of his clothes and necklace, feeding on him for several days.

"The bear did eat most of this guy," he said. "He was about 85 per cent consumed."

Friends became concerned about Horton on October 11 and called the sheriff's department. They also visited his property and could smell the decaying body, Horton said.

Horton stressed that the bear was acting naturally after finding the man's lifeless body, and said black bears are normally timid and non-aggressive.

Wildlife officials in California report there has been no known fatal maulings by black bears.