Crouching in the sun-dappled undergrowth atop the Virunga Mountains in eastern Zaire, Ndungutse, a 180-kg mountain gorilla, munches quietly on a fistful of leaves. Nearby a dozen family members swing from vines and forage lazily for food. In the still morning air, the huge silverback male and his group seem blissfuly unaware that just a few kilometers away, some 750,000 Rwandan refugees are camped on the boundary of the Virunga National Park, Africa's oldest game reserve and one of two remaining habitats for mountain gorillas in the world. Until recently, local conservationists hoped the great apes' illusion would persist. "We thought that we had emerged from [the refugee crisis] pretty well," Annette Lanjouw, coordinator of the International Gorilla Conservation Program, said last week. "Now it looks like we spoke too soon."

In the past two months, four adult gorillas, including two of Ndungutse's brothers, have been killed, three of them shot point-blank in the heart with an automatic rifle. Four others were slain earlier this year in neighboring Uganda. The killings are the first in more than a decade and have had a profound effect on the Virungas' 300 remaining animals. The loss not only further reduces a severely diminished gene pool, but by scattering at least 40 of the victims' traumatized relatives into the deep bush and away from human visitors, it threatens a fledgling tourism program that conservationists believe is the best hope for preserving the species. And the risk of more deaths is not going away. "This is a critical time for the mountain-gorilla population," says IGCP Rwanda director Katie Frohardt. "As tensions mount in the region in coming months, the threat to the animals can only grow."

The recent victims were all among the so-called habituated groups, those who after years of conditioning by game wardens, researchers and tourists learned to trust human visitors. One of the first to die was Rugabo, a massive silverback known for his gentle strength and willingness to countenance streams of camera-clicking onlookers. That trust, of course, proved his undoing. "These animals wouldn't have realized until the last moment what was going to happen," says Bruce Davidson, a British filmmaker who has worked in Zaire for eight years and was filming in the park when the gorillas were shot.

Just why these gorillas were slain remains a mystery. In Rugabo's case, an infant was removed from the group and recovered later, but in the other incidents there was no evidence that the adults were shot for their young, their meat or, as is common with other primate species in Africa, for their feet and hands, which are sold as fetishes. Local authorities say well-armed Hutu militia moving back and forth into neighboring Rwanda, which is on the park's eastern border, might have chanced upon the animals and shot them out of fright or for drunken sport. Trigger-happy poachers, either Rwandan or Zairian, who encountered the animals while hunting for smaller game, could also have been responsible. Though such activity has been going on for years, the difference now, says IGCP's Lanjouw, is the sharp increase in the number of weapons in the region after the arrival of the defeated Rwandan army. "In the past," she explains, "poachers would enter the park with snares and spears. Now they are going in with AK-47s."

The proliferation of weapons has had an alarming impact on other park species as well. Thousands of hippopotamus carcasses now litter the banks of the sleepy Ruchiru River north of Goma. Conservationists estimate that as many as half the original population of 25,000 has been machine-gunned in the past 12 months, mostly by undisciplined Zairian soldiers taking advantage of the prevailing lawlessness. Elephants, antelope and buffalo are also routinely killed, and chimpanzees living near one of the largest refugee camps are under threat. "You don't even count any more," says Popol Verhoestraete, a local conservationist.

But the gorillas, because of their small numbers, are the most endangered--and not just because of gun-wielding killers. In the space of 12 months, refugees have cut down the equivalent of 3,300 hectares of forest for cooking fuel. Though the United Nations has begun supplementing the camps' firewood, 700 metric tons are still being carried out of the park each day, further encroaching on the gorillas' habitat. Moreover, half the park's bamboo forest, a staple in the gorilla diet, has been cut, mainly for baskets and mats in the camps.

In coming months, security throughout the region is likely to deteriorate further. The Zairian government has given the refugees until the end of the year to depart. Since few seem willing to do so voluntarily, authorities are threatening to resume the use of force, which will in turn drive more people into the deep forest where the gorillas live. In response to the crisis, the IGCP this month began funding dawn-to-dusk guards for habituated groups of animals in both Rwanda and Zaire. The organization is also bringing in bulletproof vests for the game wardens, who concede that they are terrified of the growing numbers of heavily armed men in their reserve.

Such measures, however, may not be enough. Zaire's refugee crisis and the accompanying insecurity are clearly beyond the capabilities of local authorities to manage. And many refugees believe they have more pressing concerns than the welfare of a handful of lesser primates. "Everything is always blamed on us," says Jean Baptiste Sibomana, president of the Kibumba refugee camp on the park boundary. "It is too hard." That is surely true, but with time, the refugees may well recover from Rwanda's terrible civil war. The world's last mountain gorillas, sadly, may not.