WE had been looking for a group of mountain gorillas for about 90 minutes, walking, sometimes climbing, through a thick jungle undergrowth of the Virunga volcanic forest here in Rwanda.
Here, where Dian Fossey did her research on mountain gorillas, the subject of the movie ``Gorillas in the Mist,'' my wife, Betty, and I were getting closer to seeing our first great ape.
Gorillas in zoos are lowland gorillas - brownish, short-haired, and not as big or as strong as the black, long-haired mountain species. Now we could see where the mountain giants had trampled down bushes and snapped bamboo. And as we got closer, we could even smell them.
Suddenly, one of our guides stopped and pointed to a large silver-back (male) sitting on the path only a dozen yards or so ahead of us. Before I could think, he charged.
What do you do when a 450-pound gorilla charges you on a narrow path bordered by prickly bushes? The guides had stepped off the path; but Betty and I were dead center in his way as he rushed toward us.
With little choice we leaped backward into the thorny brush, as he sped by, stepping on my foot as he passed. Then he turned, stared at us, and calmly walked up to where I was cowering in the bushes, warily scribbling notes. Betty had recovered enough aplomb to resume snapping photos.
He sat down within an arm's length of me. Now what? I wondered, more than a little shaken. I had heard you should never look gorillas in the eye; it is supposed to anger them. With covert glances, I marveled at his massive body, wondering how strong he was ... and how easily he could swing at me with his log-like arm.
``No problem,'' called Sylvester, one of our three guides.
No problem? OK. Sure. No problem. Then I remembered our guides had told us to always stay lower than the gorilla's head. That was easy; I was still on the ground, oblivious to the thorns. Then the silver-back calmly lumbered off on all fours. We had done the right thing, instinctively, said Greg Cummings, director of the United Kingdom office of the Dian Fossey Gorilla Fund. ``If you get charged, never run. A silver-back wants to know that you know he's in charge.''
Other gorilla ``etiquette,'' Mr. Cummings says, includes avoiding eye contact with them - ``It's akin to calling insults'' -
and avoiding physical contact. Stay seated or stooped when moving near them, he advises. And no flash photos, our Rwandan guides added.
For a delightful hour, our guides, Sylvester Bararwiha, Sylvester Serushago, and Sharan-Birikano, led us through the bamboo forest, close behind the four silver-back males, three females, and two youngsters. We got close to the gorillas many times, often within a few feet, without disturbing them.
One silver-back walked right by Betty as she was looking in the other direction, taking a photo of another gorilla. ``To turn around when you're expecting a person, and see a gorilla walking by within a few inches ... he was upright, so he was my height. It shocked me,'' she said.
One of the youngsters, a 3-1/2-year-old, approached the guides several times to play, but they shooed it away. One time the mother of this curious youngster came down the path near us, grabbed the young one by an arm, flipped it onto her back, then walked off.
``Kosa,'' the one who had charged us, showed off a bit, pulling down bamboo stalks to demonstrate his strength, only to be outdone by an even larger silver-back, who pulled down a bigger bamboo branch with ease.
``The strongest is the one who gets the female,'' Serushago said. Some males weigh up to 250 kilos (625 lbs.), he said.
Tourists can have only an hour's visit with the mountain gorillas, and no physical contact is allowed, so that the gorillas won't grow attached to humans and become more domestic than wild. But researchers have been visiting them since the 1950s, and tourists since the mid-'80s, so some groups of gorillas have become almost blase about homo sapiens.
Some of the interaction with humans has not been good. Kosa, for example, has only one arm, the result of being caught in a snare set for antelopes when he was young. Poachers once hunted these mountain gorillas for sale to zoos; but none has survived more than a year in captivity, for reasons which remain unclear. Ms. Fossey brought such worldwide attention to the gorillas that the Rwandan government finally mounted an effective antipoaching program.
But the biggest threat to the mountain gorillas in recent times has been a three-year civil war between rebels of the minority Tutsi ethnic group and the Hutu-dominated government. They signed a peace pact in August, and tourist visits to the gorillas have been picking up again since then.
We had to pass more than a dozen government military roadblocks before reaching the park. We were stopped at only one, near Zaire (we stayed the night before in Gisenyi, near the border), but were quickly waved through after showing our passports.
Some fighting during the war took place in the park, and at least one gorilla was shot by soldiers, apparently by accident. No one knows how many other gorillas may have been killed because three of the park's volcanoes were supposedly mined by rebels and are still considered off limits to visitors.
And there's another problem: People are encroaching on the gorillas' habitat, having already cut a swath up to 250 meters (820 feet) into the bamboo forest in some places, according to Dieter Steklis, who until August was director of the Karisoke Research Center. The Center, located in the park, was started in 1967 by Fossey, who was murdered here in 1985.
Mountain gorillas, already considered critically ``endangered,'' may perish ``if we can't preserve the ecosystem,'' says Dr. Steklis, a professor of anthropology at Rutgers University in the United States.
According to the most recent census in 1989, there were about 650 mountain gorillas, about half of them in the volcanoes of the Virunga Mountains here, which run on both sides of the Zaire-Rwanda border and up into Uganda. The other half live in the Impenetrable Forest of Uganda. Uganda has begun a tourist program, but the gorillas there are less accustomed to people and are more shy; visitors are not always sure of seeing them, Cummings says.