A baby mountain gorilla in the Sabyinyo Mountains of Rwanda. (Ivan Lieman/AFP/Getty Images)

As if we needed another argument against war, here goes: It’s bad for wild animals.

This is true even with low-level conflict, and it’s especially true if the conflict repeats or drags on, according to a new study published in Nature. In a wide-ranging examination of the net effect of such disruptions on African wildlife populations over more than six decades, researchers found the frequency of war — rather than the intensity — to be a key factor in declines of wildlife.

“It takes a relatively little amount of conflict, and a relatively low frequency of conflict, before the average population is declining,” said lead author Joshua Daskin, a conservation ecologist and postdoctoral fellow at Yale University. “All the socioeconomic things that come along with a war are probably making conservation quite difficult.”

The researchers’ conclusion might sound obvious, but there has been little previous examination of the overall impact of armed conflict on animals. The case-study work to date focused on specific conflicts’ consequences and actually found both positive and negative effects.

Those downsides are numerous. Land mines and bombs can kill fauna as well as human targets. Armies sometimes intentionally destroy critical habitat — by dumping herbicides on forests, for example, as the United States did during the Vietnam War — or finance their fight by selling ivory. Collapsed institutions mean less enforcement of laws protecting animals, and economic fallout can force desperate civilians to hunt wild animals for food.

On the other hand, wars can also cause human displacement, and “anything that causes people to vacate can be a beneficial thing for nonhuman wildlife,” said co-author Robert Pringle, an assistant professor of ecology and evolutionary biology at Princeton University. Poaching and habitat destruction might slow, and mining might stop. This is sometimes called the “refuge effect,” and it can be seen in the demilitarized zone dividing North Korea and South Korea.

Pringle and Daskin, who finished his PhD at Princeton last year, both do research in Mozambique’s Gorongosa National Park, where a 15-year civil war nearly decimated wildlife. They wanted to know more about the big picture — is war generally positive, negative or neutral for wildlife? Among other reasons, they note, the question is important because the vast majority of wars since 1950 have taken place in the world’s most biodiverse regions.

An elephant in Hwange National Park in Zimbabwe. (Martin Bureau/AFP/Getty Images)

The pair decided to focus on protected areas in Africa between 1946 and 2010. They mapped events  there using a standard definition — fights that killed at least one person in a broader battle that caused 25 human deaths in a year — and found conflicts in a depressing 71 percent of the areas during that time period. Then came the hardest part: finding reliable wildlife population data.

Daskin said he used published research as well as “gray literature” such as park management figures, government wildlife agency documents and reports from nongovernmental organizations. He looked only at populations of large herbivores, in part because they “have really outsize roles in maintaining these ecosystems,” but also because they’re counted more easily and therefore more frequently. In the end, Daskin had data for 253 wildlife populations and 36 species, including giraffes, warthogs and wildebeests.

Next, the authors looked at correlations between wildlife populations and variables that can influence them, like drought, human population density and the presence of mining, as well as two factors related to war: conflict frequency and conflict intensity.

When they crunched it all together, the biggest and only statistically significant predictor of wildlife declines was conflict frequency. While wildlife population trajectories stayed stable in peaceful times, they dropped with even a slight increase in conflict and were “almost invariably negative” in high-conflict zones, the authors found.

Pringle said they were somewhat surprised that conflict intensity wasn’t correlated with dips in wild animals. The numbers don’t suggest why, and Pringle said understanding these dynamics will take more research with larger data sets. But he and Daskin have some theories.

“Our interpretation is that conflict destabilizes everything. When people don’t feel secure, institutions start to break down, livelihoods start to be disrupted,” Pringle said. Yet intense conflict may provide a buffer for wildlife because “people evacuate. People don’t hang around and go set snares in the forest.”

Cinereous vultures on a rice paddy in South Korea near the demilitarized zone with North Korea. The area has become a nearly untouched nature refuge. (Jeon Heon-Kyun/European Pressphoto Agency)

The researchers emphasized that their findings were not limited to gloom. The only cases of extinction in the areas they studied took place in the Pian Upe Wildlife Reserve in Uganda, where giraffes and two species of antelope vanished between 1983 and 1995.

“War is awful for people. It’s bad for wildlife. But it’s not so cataclysmically bad that we should be giving up on anything,” Pringle said. “In fact, there are great opportunities for restoration.”

He and Daskin hope their findings can help governments and wildlife organizations better predict and mitigate the influence of conflict on wildlife. Both point to the place where they do work — Gorongosa National Park — as an example. It lost about 90 percent of its wildlife during the war that ended in 1992, but it’s now back to “about 80 percent of the prewar populations,” Daskin said.

“That’s been achieved not just by trucking in large numbers of animals from other protected areas, as has often been highlighted, but by creating the conditions in the local region for conservation to be possible,” Daskin said. “It’s an excellent case study in what can happen after the conflict.”