Down for the Count

Elephant populations continue to dwindle in Tanzania.

Elephants gathered at a watering hole in the relative safety of Serengeti National Park. In unprotected areas with dense human populations, the animals showed higher stress hormone levels.

Photographs by Daniel Rosengren

An elephant does not die from one broken rib. Or so says an African proverb. But elephants certainly suffer in greater numbers the closer they are to people, according to a study of these usually gentle giants in and near Tanzania’s iconic Serengeti National Park. The 5,700-square-mile park, established in 1951 and later designated a UNESCO World Heritage site (1981), is home to some 2,000 African elephants, Loxodonta africana, the largest terrestrial animals alive today.

How well do elephants fare when they’re close to humans? To find out, ecologists at the Norwegian University of Science and Technology (NTNU) conducted research from March through July 2010 in more than 6,000 square miles of Tanzanian savanna and woodland. The team, led by evolutionary biologist Eivin Røskaft, hoped to learn whether elephants fare better inside Serengeti National Park than in the adjoining and heavily human-populated Grumeti Game Reserve and Fort Ikoma Open Area.

The elephants’ stress was measured by tracking metabolites of glucocorticoids, or stress hormones, in their dung from the three locations. The results show that elephants feel most under fire when they’re outside the park. “No wonder more elephants are seen inside the Serengeti limits,” says Røskaft. “They’re avoiding people on the outside.” Discovering where and how human disturbance affects elephants in and around the Serengeti “may offer a missing piece in the conservation puzzle,” he says.

The study partitioned the 6,000-square-mile area into four sections, giving each a rating based on risk of hunting and level of other human activities: the northern Serengeti, which the researchers labeled “moderate risk”; the central Serengeti, low risk; the Serengeti’s western corridor, moderate risk; and Fort Ikoma Open Area and Grumeti Game Reserve, both high risk. In the Grumeti Game Reserve, trophy hunting of some species, excluding elephants, is allowed for several months each year. In the Fort Ikoma Open Area, legal hunting is strictly controlled, says Røskaft, but illegal hunting for bushmeat and ivory nonetheless continues. Poverty-level villagers say they need the economic benefits.

Whether inside or outside the park, elephants’ stress hormones mirror the amount of human activity. “Somehow,” says Røskaft, “elephants must ‘know’ when they’re in an area that could be a risk.” The biologists are also looking at stress in elephants in Tanzania’s Selous Game Reserve and in northern Namibia, as well as in impalas, or African antelopes, in the Serengeti.

High levels of stress hormones likely result, Røskaft says, “from ongoing hunting activity, which has led the animals to associate humans and vehicles with bad outcomes. Elephants, in particular, probably remember where they’ve been. If they’re back in an unsafe place, the memory of the previous experience stresses them.” Røskaft thinks elephants realize, sometimes too late, when they’ve wandered into a danger zone far from an invisible fence: the perimeter of Serengeti National Park. (People soon may be further encroaching on the territories of elephants and other species inside the park, if a controversial gravel road through the Serengeti goes forward; the Tanzanian courts are reviewing proposals as we go to press.)

In the wet season, water holes offer plenty of water for these Serengeti elephants.

Grassland ecologist Marissa Ahlering of the University of North Dakota and the Nature Conservancy also found that elephants pilfering farmers’ crops had higher levels of stress hormones. Levels of glucocorticoid metabolites in dung collected from fields where crops had been raided revealed that elephants may anticipate the potential risks of getting too close to people. [See the sidebar, “Bee Fences,” on page 32 for more about elephants raiding farms.]   

Some 481 miles southeast of Serengeti National Park lies Tanzania’s approximately 20,000-square-mile Selous Game Reserve, one of the largest protected areas in the world. Because of the diversity of its wildlife—and its undisturbed landscape—the Selous was designated a UNESCO World Heritage Site in 1982. Yet, despite its vast space, elephants don’t seem to be faring well there. Results from a wildlife census conducted in October and November of last year show a dramatic decline in elephant numbers.

Wildlife surveys in the Selous, an area twice the size of Switzerland, have taken place since 1976, when 109,419 elephants inhabited the reserve. Heavy elephant poaching for ivory has cut down the population; an estimated 13,084 elephants remain. In the last four years alone, the Selous has lost two-thirds of its elephants. It’s one of Tanzania’s—and Africa’s—most brutal killing fields.

Elephants foraging near a farm just outside the boundaries of the Serengeti

Bee Fences  

Where there are farmers along the perimeter of Serengeti National Park, there are elephants—and all manner of attempts to protect crops. Farmers have tried various elephant-deterring techniques, from beating tin cans to lighting fires, most of which haven’t appeared to work. Now officials in Tanzania’s Mara Region near the park have asked authorities to construct fences to keep elephants away from villages and agricultural holdings. The question, however, may be larger than “to fence or not to fence.” How do humans and elephants live side by side? Biologist Lucy King, leader of Save the Elephants’ Elephants and Bees Project, may have an answer: beehive fences.

Beehive fences are simple and cheap, according to King, and are made with locally sourced materials. Hives are hung every thirty feet and linked together. If an elephant touches one of the hives, or the interconnecting wire, the beehives all along the fence swing and release the stinging insects inside. Bees do not like elephants. The feeling, it appears, is mutual. A tiny bee may have more strength than a thundering herd of pachyderms.


In the recent census, three aircraft were flown above the reserve at an average height of 350 feet, with transects spaced three to six miles apart. Animals were spotted in strips about 500 feet wide on both sides of the planes. In total, 203 transects were covered, along which 712 elephants were counted. That gave an estimate of 13,084 elephants in the Selous as a whole. The elephants’ density wasn’t evenly distributed across the reserve, however. The highest numbers were in small pockets in the northwestern, central, and southern areas.

In the area surveyed, almost 80 percent of the elephants were within the boundaries of the Selous. Some 12 percent, however, risked living outside the protected area. Eight percent of the elephants were located to the south of the Selous in the Niassa Corridor, and four percent to the north in Mikumi National Park. None were seen to the west in the Kilombero Game Controlled Area.Dead elephants were also counted. More than 300 were recorded, resulting in a total estimate of 6,516. The elephants had died over a period of about three years. The highest numbers were found in the Kingupira sector in the northern part of Mikumi National Park, and in the central section of the Selous.

What of the elephants left alive—elephants that may have come across the bodies of their kin? In the poaching wars, elephants have their own version of burying the war dead. When they lumber across the bones of one of their own, elephants often throw leaves and dirt over the body and break off tree branches to cover it. They may quietly stand over the grave for hours or days, and later return—only to blunder into the hands of poachers themselves.

Increased demand for ivory, particularly in the Far East countries, and, therefore, price increase is a catalyst and a key determinant for the recent widespread elephant poaching,” states Lazaro Nyalandu, Tanzania Deputy Minister for Natural Resources and Tourism, in a news release reporting the 2013 census results. [On the ivory trade in Western countries, see “The Big Ivory Apple,” Natural History, July/August 2013.] The elephant-poaching epidemic continues to escalate across Tanzania. Robert Muir, director of the Africa office of the Frankfurt Zoological Society, cites the importance of the surveys. “They’re critical to understanding changing ecosystems, and to supporting conservation efforts,” says Muir.

If Tanzania’s wildlife habitat is at risk, so may be the country’s fiscal health. The Selous is one of the largest remaining wilderness areas in Africa, and as such is an important tourist destination. For both conservation and economic reasons, protecting the natural resources of the Selous is a priority, says Muir. “The future of the elephants hangs in the balance, and we’re calling on the international community to unite in a concerted effort to support the Tanzanian government as it strives to secure the Selous.” 

Røskaft and other scientists were surprised and alarmed by the 2013 count’s revelation that the Selous elephant population had plummeted so precipitously. “In 2006, it was somewhere around 70,000 elephants,” Røskaft says. He points to the ramifications of a declining elephant population. With the removal of elephants from the Selous, the entire ecosystem may be altered. “The elephant is a keystone species, so even if poaching stops now, there are likely to be a lot of habitat changes,” Røskaft cautions. Without elephants munching on vegetation, “the woods will grow denser,” he believes, “which in turn will affect other species.”

One has only to look north to see the truth of his prediction. In the Serengeti, elephant poaching was rampant in the 1980s. As elephant numbers fell, trees sprouted like weeds. But across the Tanzanian border in Kenya, where an anti-poaching effort was underway at that time, trees were—and still are—fewer. Elephants nibbled on saplings’ tender shoots and on trees’ post-fire regrowth, and continue to do so today.

Røskaft believes there’s “an urgent need to follow up with science to understand what’s going on in the Selous. The tragic decline in this elephant population is not only a Tanzanian issue; it’s the responsibility of the world community.” The 2013 wildlife survey, which involved several national and international conservation groups, is among the most recent steps to assess the extent of the poaching. According to Muir and Røskaft, however, there’s already talk of a need to re-survey.

In a streak of light on an otherwise dark canvas, the census revealed that about 5 percent of the dead Selous elephants had been killed within the previous year. Nearly 30 percent had died three years or more before the survey. The slaughter peaked between twelve and thirty months before the tally, then dropped off sharply. To move forward, the Ministry for Natural Resources and Tourism “is finalizing the process of establishing an autonomous body—Tanzania Wildlife Authority,” Nyalandu announced. The Ministry is “determined to intensify the protection of wildlife in collaboration with other stakeholders, including defense and security forces and regional and international conservation institutions,” he says, as well as to “promote education and adopt strategies aiming at involving the public in conservation efforts.” 

The 2013 Selous census was “a landmark event,” believes biologist Iain Douglas-Hamilton of Save the Elephants. The results confirm that the elephant population has been decimated, he says, but also offer hope for Tanzania, with help from international support, to plan for the elephants’ recovery.

Until then, Selous elephants should perhaps learn another proverb, well-known to their Serengeti neighbors: Kikulacho kinguoni mwako. That is, your problems often originate from those closest to you.

Elephants in the early morning light, with zebras in the distance