The savanna isn’t the same after Mozambique’s civil war

(Credit: RTP/Flickr)

Animals have returned to Gorongosa National Park after Mozambique’s civil war, but the savanna community doesn’t quite look like it used to, researchers report.

When civil war broke out more than 40 years ago, it largely spelled doom for animals in the park, a 1,500-square-mile reserve on the floor of the southern end of the Great African Rift Valley, in the heart of the country. As the decades-long fighting spilled over into the reserve, many of the creatures became casualties of the conflict.

“More than 90% of the large mammals in the park were wiped out.”

Throughout the war and even for some time after, food insecurity drove people to kill the animals to feed themselves. The hunting and poaching hit large mammals the hardest.

“More than 90% of the large mammals in the park were wiped out,” says Kaitlyn Gaynor, a postdoctoral researcher at the University of California, Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS). After the war, a massive recovery effort was launched to repair and restore the park in the hopes that the animals would make a comeback.

With the park now three decades post-war, it appears the animal populations have recovered. While ecologists have reintroduced some animals, most have simply rebounded from remnant post-war populations thanks to ongoing conservation efforts.

But for all the growing abundance in animals in the park, questions about the ecological consequences of the war remained.

“How similar is this new system to pre-war conditions, or to African savannas that haven’t seen this major shock?” These were the questions the researchers sought to address, using an array of 60 camera traps to document the comings and goings of the animals of Gorongosa.

The results appear in the journal Animal Conservation.

A new normal for Gorongosa Park

“There are few places in the world that have had such a dramatic reset, where animals have been pretty much wiped out and then have come back,” Gaynor says. “It looks a lot like it did before the war, if you look at just the numbers of total animals, or the number of species present throughout the landscape.”

“When you take a closer look at the distribution of species, it’s a bit out of whack.”

The researchers identified 38 species during the three months of their survey, which puts Gorongosa’s biodiversity on par with other African savannas, such as the Moremi Game Reserve in Botswana’s Okavango Delta and Serengeti National Park in Tanzania.

But that’s where the similarity ends.

“When you take a closer look at the distribution of species, it’s a bit out of whack,” Gaynor says. The large herbivores that were dominant before the war—iconic African animals like zebra, wildebeest, and hippopotamus—were rare. Large carnivores were rarer still, with only lions remaining after the war. The savanna now belonged to baboons, warthogs, bushbuck, and especially waterbuck, which dominated the survey.

“Waterbuck have been reproducing exponentially,” Gaynor says, adding that it remained to be seen whether the unchecked population might crash and stabilize, or if their dominance signaled a “new normal” for the park.

Additionally, in the first systematic study to focus on smaller predators in the park, the researchers also found a high diversity in mesopredators—housecat sized animals such as civets, mongoose, and genets—which were widespread throughout the park.

“There may have been a ‘mesopredator release,’ where in the absence of apex predators, the smaller predators’ populations can grow because they’re not facing competition, or they’re not being preyed upon by the larger carnivores,” Gaynor explains.

Changes to environment, too

All of this is happening against a backdrop of environmental change: Tree cover increased while the herbivores (especially elephants) were absent, but with their return and increased feeding pressure the landscape might shift again, potentially influencing which species may flourish. A variety of tree cover is important for promoting the diversity of the animals, according to the researchers.

Time will tell whether the distribution of species in this park will return to pre-war levels, or if they will level off at some other stable state. Since the study was conducted, African wild dogs and leopards were reintroduced in an effort to rebalance the ecosystem. The slow return of large carnivores is bound to shape the dynamics of Gorongosa’s animal community, and the researchers are hoping to document those and other developments in future studies.

“Our study represents the first data point in what will hopefully be a long-term, ongoing camera trap monitoring effort,” Gaynor says. “Gorongosa has been a really remarkable conservation success story, but I think it’s also pretty interesting how the system has recovered asymmetrically.

“There remain questions about the causes and consequences of that asymmetry, and how the wildlife community is going to change in the future, given ongoing transformations to the landscape.”

Additional coauthors are from the University of California, Berkeley; the US Fish and Wildlife Service; and the California Department of Fish and Wildlife.

Source: UC Santa Barbara