Vultures of Eden
As if out of thin air, vultures begin to fall from the sky like a squadron of untidy planes that have all suddenly lost power. The big birds are in a hurry to join those already on the ground, and they do little to slow their descent until just moments before impact. When they do finally tilt their broad wings up to brake, the rush, like a giant inhale, is all that cuts through the still morning air and the disquieting hum of flies drawn to the stench.
For a few moments, the vultures stand, looking uncertain, wary, unwilling to make the first move. Then one bird makes a break for it and the hushed gathering suddenly becomes a frenzy. While the 160-kilogram (350-pound) waterbuck carcass the birds lurch toward appears big enough to sustain the entire group for days, the vultures seem to know better. Hunger is a powerful driver. At this sort of banquet, speed, positioning, and aggressiveness may mean the difference between nourishment and starvation—both for the vultures here and for any chicks they might have back at their nests.
Despite the flying feathers and hair, clouds of dust, and angry squawks, the birds are singularly focused on consuming as much flesh from this carcass as possible. With their sharp, down-curved beaks, they stab into waterbuck flesh. Then, with powerful neck and leg muscles, they pull and tear away whatever stays within their grasp—muscle, tendon, intestine. They’re not picky as long as it can be swallowed. Every bird within striking distance repeats this motion again and again, and in less than an hour, most of the edible bits have been consumed. After another hour, what was a large-bodied antelope a day or two before has been reduced to bones and hide.
The efficiency with which vultures can remove flesh from a carcass is legendary. They’re cleaning machines, all but perfectly adapted to feeding on rotting carcasses. And in most ways that’s true. But here, on this parched floodplain in Mozambique’s Gorongosa National Park, these consummate scavengers would have been out of luck had it not been for the three fresh cuts that biologist Jen Guyton made through the waterbuck’s tough hide, giving the birds access to the flesh underneath. Although the vultures’ hooked beaks are sharp enough to pierce the hides of smaller animals, they’re unable to access thick-skinned carcasses like this one without the help of larger scavengers like hyenas and wild dogs—animals still missing from this recovering ecosystem.
It’s an unusual scenario, but Gorongosa is no ordinary place. Its unique history has left the park’s ecosystems oddly unbalanced and incomplete. Yet, given the state of Gorongosa just a decade ago, many view the park as a remarkable conservation success story. And despite the challenge posed by the current lack of some formerly abundant species, Gorongosa and protected areas like it may be the only hope of saving what remains of Africa’s rapidly dwindling vulture populations.
Once called “Africa’s Eden,” Gorongosa National Park has had a storied and, at times, traumatic past. Established in 1960, the park, which sits near the southern end of Africa’s Rift Valley and covers roughly the same area as the state of Rhode Island, once boasted some of the largest populations of big animals in all of Africa. A 1969 survey tallied more than 2,000 elephants, 14,000 buffalo, and more than 200 lions. By the 1970s, Gorongosa had become Africa’s most popular national park among foreign tourists, attracting the likes of movie stars John Wayne and Joan Crawford, and Apollo astronaut Jim Lovell. But the heyday was short-lived.
In 1977, just two years after Mozambique’s independence from Portugal, the country fell into a state of civil war that would last 16 years. In addition to the countless human atrocities committed during the conflict, warring factions—and the impoverished communities they left in their wake—devastated Mozambique’s wildlife. In 1994, when scientists conducted the first post-war surveys of Gorongosa, they found only remnants of the park’s famous herds. A mere 100 elephants, 15 buffalo, and a handful of zebra remained. Gorongosa’s once-famous lion population had fallen by 80 percent. And those were just the animals anyone bothered to count.
In 2004, although many people had already written Gorongosa off as a catastrophic ecological loss, former tech entrepreneur turned philanthropist Greg Carr was looking for a new challenge and turned his attention to Gorongosa. Carr’s initial pledge of $500,000 toward Gorongosa’s restoration ballooned to $40 million the following year in a 30-year agreement with Mozambique’s Ministry of Tourism to both restore the park’s ecosystems and promote economic development in the region. Since that time, the Gorongosa Restoration Project has managed and studied existing wildlife populations and has begun to restock species struggling to recover on their own.
One thing the restoration scientists have going for them is that Gorongosa’s habitats remained relatively intact throughout the war, and since. Rains continue to fall each year on nearby Gorongosa Mountain, gathering in streams that turn the park’s Lake Urema into a vast, rich floodplain. Old-growth forests, for the most part, still stand in the park’s interior. These ecosystems harbored many smaller animals through even the worst of the disruption, and today they offer safe haven for the increasing number of species that are returning—either on their own or with the help of Gorongosa’s restoration team. While vultures still face challenges here, the birds are among the creatures that are thriving in this comeback story. The park now supports the largest known population of white-headed vultures (Trigonoeps occipitalis) anywhere in Africa.
Within the relative safety of Gorongosa National Park, vultures find both priceless nesting habitat and growing populations of potential food sources. Unfortunately, these highly mobile birds don’t stay within the park boundaries. Vultures are obligate wanderers, and given the right conditions—thermals that rise vertically over southern Africa’s grasslands and savannas on any given day—they make long-distance travel look easy. Within minutes, a bird can glide beyond the protected parklands, and can cross international borders with only slightly more effort.
When paired with their keen eyesight, this mobility affords vultures access to food sources that most animals would never see or be able to reach. But their wide-ranging habits also expose them to threats that more sedentary species wouldn’t encounter. Among the many perils that African vultures face outside park boundaries are collisions with power lines and hunters eager to supply markets with vulture body parts that practitioners of traditional medicine say confer clairvoyance. But by far, the greatest threat to vultures in Africa—and in fact around the world—is poisoning.
Poisons account for more than 60 percent of vulture mortality in Africa. In some cases, the poisoning is incidental, intended for other scavengers such as hyenas or for predators like lions that threaten livestock. Increasingly, though, the poisons are intended specifically for vultures, left by poachers who have learned that the circling birds give away the location of their crimes. In the most deadly of these events, in 2013, a single elephant poached and then laced with poison near Namibia’s Bwabwata National Park killed nearly 600 vultures.
The impact on vulture numbers across the continent has been devastating. All eight species in Africa have seen population declines of at least 70 percent over the past 50 years, and five species have declined by more than 90 percent during that time period. To raise awareness about this troubling trend and to slow its rate, the International Union for Conservation of Species (IUCN) has listed seven of the eight African vulture species as Endangered, and four of those as Critically Endangered.
The IUCN has also convened a group of experts to develop a multi-species action plan for vulture conservation across Africa, Europe, and Asia. André Botha, a raptor biologist at South Africa’s Endangered Wildlife Trust, is one of the authors of this plan, which will be presented at the Conference of the Parties (COP12) meeting in the Philippines next week. “Protected areas like Gorongosa play an important role in vulture conservation,” Botha says, “but by themselves, they can’t protect these birds adequately.”
In an effort to design conservation strategies that might slow the plummet of vulture populations across Africa, the Gorongosa Restoration Project recently teamed up with Botha’s Endangered Wildlife Trust and researchers from Boise State University’s Intermountain Bird Observatory. The goal of this collaboration is to find out where and how the park’s vultures spend their time, how far afield they wander, and what threats they face along the way. Over the past two years, the team has tagged 16 birds—seven white-backed vultures (Gyps africanus) and nine white-headed vultures, both of which are critically endangered species. After capturing the birds and taking measurements and blood samples, the team placed GPS transmitters on the vultures and have been following their movements ever since.
The scientists’ observations have confirmed that many of Gorongosa’s vultures venture far outside the park. The birds travel as much as 160 kilometers (100 miles) a day, and some have been observed as far afield as South Africa, up to 1,600 kilometers (1,000 miles) from Gorongosa. “They’re traveling huge distances, especially the younger ones,” says Greg Kaltenecker, Director of the Intermountain Bird Observatory who is leading the study. “Even though we trap them in Gorongosa, a few weeks later they could be thousands of kilometers away.”
Eventually the birds make their way back, but for researchers like Botha and Kaltenecker, it’s unnerving to consider the countless dangers the vultures—some of the most endangered creatures on the planet—encounter when they’re outside the protective borders of the park.
Although vultures have long been taken for granted, even reviled, their recent precipitous declines are motivating many people to take notice—and to help policymakers see what a world without these creatures might look like. Even in Gorongosa, with its relatively healthy populations of vultures, it’s possible to get a glimpse of that world.
In the dry season, when the vast floodplain shrivels and cracks, many of the park’s herbivores succumb to starvation and disease. Understanding what happens to these animals’ bodies after they die is what motivates ecologist Jen Guyton, a Princeton University Ph.D. student, to brave the stomach-turning stench of rotting flesh and the potential spray of putrid body fluids as she slices into carcasses on the floodplain. Guyton, who captured many of the photographs for this story in the course of her work, is conducting a field experiment to understand what happens when large mammalian scavengers, like hyenas and wild dogs, are missing from an ecosystem. But by extension, her research also reveals what happens when vultures are taken out of the equation.
Without hyenas and other scavengers to tear open large carcasses, these enormous food sources are left to rot or dry up in the hot sun and desiccating air—like “carcass jerky,” Guyton says. A disposal process that would typically take an hour or two when vultures are able to do their work may instead play out over the course of several weeks or months, allowing mongooses and other small mammalian scavengers time to access the carcasses and become infected with the bacteria they contain.
Not surprisingly, scenarios like these have the potential to increase the spread of disease. Vultures are largely immune to microbes that cause diseases such as rabies, anthrax, and brucellosis, so they can quickly reduce the numbers of these microbes in the environment when they descend on an open carcass. Without vultures, the bacteria are more likely to persist and spread among animals that are far more susceptible, including humans.
What’s clear from this and other research in Gorongosa National Park is that vultures are critical members of this recovering ecosystem, and their relative success here has surely played a role in the overall resilience of the park. Gorongosa, in turn, may be just as critical to the survival of this, the most rapidly declining bird group in the world. Not only does the park provide key nesting habitat, food sources, and safety from persecution, but it’s helping scientists understand the risks vultures face beyond the park’s borders.
Although there’s little that scientists and wildlife managers working in Gorongosa can do to eliminate the threats that any one bird might face outside the protections of the park, the information they gather can be used to inform international agreements around the availability of toxins and other hazards. It also highlights the need to manage ecosystems like those in Gorongosa to benefit not only the charismatic megafauna tourists come to see but the oft-overlooked scavenger, too.
Steven Bedard is bioGraphic’s Editor-in-Chief. A former field biologist who spent the early 90s chasing spotted owls and northern goshawks through the woods, he now tags along with scientists and writes and produces media about their work. Having written about archaeology, engineering, and astrophysics in the past, he’s found a much happier place covering the living world for bioGraphic. Follow him on Twitter @steventbedard.
Dr. Piotr Naskrecki is an entomologist, conservation biologist, author and photographer based at the Museum of Comparative Zoology at Harvard University. He currently directs the E.O. Wilson Biodiversity Laboratory at Gorongosa National Park, where he trains a new cadre of Mozambican biologists and conservationists. He is one of the founding members of ILCP, and his photographs and nature writing have been published in a number of national and international publications.
Jen Guyton is a National Geographic Explorer, photographer, and ecologist based in Gorongosa National Park. She is working on her Ph.D. in Ecology and Evolutionary Biology at Princeton University. You can see more of Guyton’s work at www.jenguyton.com.