In 1996, when war broke out in what is now the Democratic Republic of Congo, just 31 northern white rhinos remained in Garamba National Park, the last stronghold of this endangered species. Armed militias reached the park less than a year later, and half of the park’s elephants, two-thirds of its buffalos and three-quarters of its hippos disappeared in three short months.
Poaching of northern white rhinos also resumed, despite conservationists’ best efforts. Today, after a succession of armed clashes, only three northern white rhinos survive — all transplants from a zoo in the Czech Republic, and all confined to a single Kenyan conservancy.
That the rhinos’ habitat included a part of Africa plagued by human conflict was “desperately unfortunate,” said Kes Hillman-Smith, a Nairobi-based conservationist and author of “Garamba: Conservation in Peace and War.” “The endless wars there have taken their toll on all the wildlife in the region.”
Many case studies have demonstrated that war can affect the survival of local populations, sometimes threatening entire species. But the research is mixed: In some cases, conflict actually seems to aid animals.
Now researchers have published a quantitative study of war’s consequences for African animals — the first multi-decade, continentwide analysis. The findings, published in Nature, are both surprising and encouraging. Compared to all other measured factors, conflict is the most consistent predictor of species declines. Yet the northern white rhino is the exception.
War rarely leads to extinction, a finding that underscores the importance of post-conflict restoration efforts. “We show that war is bad, but not as bad as you might assume,” said Robert Pringle, an ecologist at Princeton University and lead author of the new study.
“There are really two alternative hypotheses you can imagine,” he added. “One is that war is just a disaster for everything, including environments. And the other is that pretty much anything that causes people to clear out from an area can be beneficial for wildlife.”
Indeed, Dr. Pringle noted, the Demilitarized Zone between North Korea and South Korea offers respite for rare species such as red-crowned cranes and Asiatic black bears.
Teaming up with Dr. Pringle, Joshua Daskin, a conservation ecologist at Yale University, undertook a laborious search of 500 scientific studies, government white papers, nonprofit reports and park management documents. He sought out comparable wildlife counts, irrespective of the presence of conflict, from 1946 to 2010.
The researchers then calculated various animal population trajectories over time and compared them with known conflicts. Their final list encompassed 253 populations of 36 species of herbivorous mammals — including elephants, giraffes, zebras, hippos and wildebeests — in 126 protected areas throughout Africa.
The scientists found that it takes relatively little conflict — just one event every two to five decades — to push animal populations to lower levels. “Even with the onset of what could be a fairly minor conflict from a human perspective, we see the average wildlife population declining,” Dr. Daskin said.
Conflict frequency, in fact, was the most significant variable predicting wildlife trends among 10 other factors the researchers analyzed, including drought, the number of people living near a protected area and the degree of corruption found in a country. The more frequent the conflict, the greater the impact.
“This continentwide assessment confirms what many case studies have hinted at — war is a major driver of wildlife population declines across Africa,” said Kaitlyn Gaynor, a doctoral candidate at the University of California, Berkeley, who has studied armed conflict’s influence on wildlife.
The losses are likely the result of a combination of factors, said Dr. Hillman-Smith, who spent 22 years in Garamba conserving the park and its northern white rhinos.
In times of war, poached bushmeat may feed troops, local people and refugees, while valuable assets like ivory and rhino horn may be used to fund the struggle. Arms and ammunition also tend to become more widely available, Dr. Hillman-Smith said, and a general breakdown of law and order makes poaching easier.
Conservation organizations, she added, also tend to pull out when the shooting starts. “The greatest losses in Garamba happened in the absence of international support and when active patrolling was stopped,” she said. “While warfare needs to be taken into account as a conservation factor, it should not be seen as a reason not to invest or to pull out too soon.”
Yet all is not lost during war, even when conservationists are forced to flee. Animals sometimes become scarcer and more difficult for hunters to find, Dr. Daskin said, and the populations persist at lower levels.
That conflict is detrimental to wildlife but rarely causes extinctions is the most important message of the paper, according to Edd Hammill, an ecologist at Utah State University, who was not involved in the research.
The finding suggests that rapid intervention by conservationists can be critical for ensuring the survival and recovery of remnant populations, he said. Indeed, in the 1980s post-conflict conservation in Garamba doubled both the northern white rhino and elephant populations in just eight years.
Renewed fighting, politics and other factors ultimately prevented the northern white rhino’s recovery in the wild. But Dr. Daskin points to Mozambique’s Gorongosa National Park as a hopeful alternative.
Following 15 years of devastating civil war, Gorongosa lost more than 90 percent of its animals. The elephant population declined to 200 from 2,000, while wildebeest and zebras numbered fewer than 50 each, down from several thousand.
As herbivores disappeared, trees encroached into the park’s formerly open grasslands, and predators became virtually nonexistent.
After peace was declared, the Mozambique government partnered with the Carr Foundation to restore the park. Rangers — including people who were previously pitted against one another in the civil war — were recruited and trained to reduce poaching and look after the animals.
Those living around the park received assistance for farming, education and health care. Several hundred also found jobs in the park.
Gorongosa now bills itself as “Africa’s greatest wildlife restoration story,” with more than 500 elephants, 60 lions and tens of thousands of antelopes.
The lesson? “Within a decadal time scale, it is possible to rehabilitate even a severely degraded ecosystem into something that is once again a natural wonder of the world,” Dr. Pringle said.