Elephants are being pushed into smaller and smaller spaces. And increasingly, they're pushing back.
According to the National Geographic Channel documentary Elephant Rage, some 500 people are killed by elephant attacks each year. Such attacks are becoming increasingly common, researchers say.
"I do think that elephants are becoming more aggressive towards humans in very compressed areas where they are being shot at and harassed," said Caitlin O'Connell-Rodwell, a biologist at Stanford University in Palo Alto, California.
"It is a difficult dilemma in areas where elephant habitat is shrinking and the human population is increasing such that poor farmers have little choice but to expand their farms to make ends meet," she said in a telephone interview from a Namibian field camp.
Elephants are the world's largest vegetarians. They don't attack any animal for food—yet food is at the root of many elephant conflicts.
An adult elephant may eat over 400 pounds (180 kilograms) a day. A herd can consume an entire field in one night. Fences and other deterrents are often useless against hungry herds.
Not only can elephants grow as large as about 13 feet (4 meters) tall and weigh as much as about 6 tons, but they can run 25 to 30 miles an hour (40 to 48 kilometers an hour).
Yet despite their size, intelligence, and speed, elephants fare worse in human-elephant confrontations. According to the Elephant Rage documentary, perhaps a thousand elephants are killed each year for their ivory or food, or because they have become a danger to humans living around them.
Overall, elephant numbers have declined dramatically. The conservation nonprofit WWF, for example, estimated that there were about 1.3 million African elephants in 1970. By 1989 that number had slid to 600,000.
In some African locales, though, elephant populations are stable or growing because of preservation measures such as bans on ivory trade.
Many protected areas, however, seem to be too small for their increasing elephant populations. As a result, officials often take steps to reduce elephant numbers through controlled hunts and other measures.
In some areas, including much of Asia, humans continue to invade elephant country even as animal populations are dwindling.
"The issue in Asia endangers the viability of [elephant] populations," said Tom Dillon, director of the Species Conservation program at World Wildlife Fund in Washington, D.C.
"The Sumatran subspecies, for example, is rapidly disappearing in large measure because [Sumatra's] forests have been cut at perhaps the fastest rate of deforestation in the world," he said. "The elephants don't have anywhere to go, so they end up causing crop damage, and then they get poisoned or shot for it."
"The traditional reverence for elephants in northeast India is eroding as people are being killed or losing their livelihoods," Dillon added.
Elephant Post-Traumatic Stress Disorder?
O'Connell-Rodwell, the Stanford biologist, notes that elephant aggression toward humans is unlike the aggression she's observed in elephant-to-elephant conflicts over many years in Namibia's Etosha National Park.
"Battles over territories rarely come to extreme violence—nothing like what is happening in India, with elephants killing farmers on a very frequent basis," she said.
During more then 30 years in Kenya, elephant researcher Joyce Poole has heard tales of elephants intentionally killing humans. Poole and Petter Granli run the Savanna Elephant Vocalization Project (SEVP), which is based in Norway and Kenya. (See "Elephants Can Mimic Traffic, Other Noises, Study Says.")
"I have always believed that these are elephants who have suffered some severe trauma at the hands of man," she said. "An elephant whose family members are killed by people is unlikely to forget it very quickly—just as you or I wouldn't forget if an elephant killed a member of our family."
Poole and numerous colleagues have studied the disruption of complex elephant social structures. They have suggested that some animals may suffer from post-traumatic stress disorder (PTSD) much like humans.
"African elephant society has been decimated by mass deaths and social breakdown from poaching, culls [systematic killing to control populations], and habitat loss. Wild elephants are displaying symptoms associated with human PTSD," she wrote in a study she co-authored in a February edition of the journal Nature.
"Much of what elephants feel, think, and do is acquired through social learning," Poole told National Geographic News.
"If a matriarch has a bad experience with people, her behavior will be adjusted accordingly—either more fearful or more aggressive depending upon her own personality," Poole said.
"Other members of the family will follow her lead during moments of crisis, and younger elephants will learn how to act. Aggressive behavior toward people can be learned. Just as children learn prejudices from their parents, so, too, do elephants," she added.
"In Amboseli [Kenya] the elephants are fearful/aggressive toward Masai [people] but not toward tourists," she noted. "The reason? They are regularly speared by Masai."
Chili Bombs and "Flying Squads"
In the fight to protect both elephants and humans, the chemical agent capsaicin, found in chili peppers, is a secret weapon. Elephants, with their very sensitive trunks, simply cannot take the heat.
As a stopgap measure, chili power, in the form of spicy ropes and exploding "chili bombs," is proving effective at protecting fields and preventing elephant-human encounters.
Meanwhile, Indians are employing "flying squads" (a term adapted from Hindi) of domestic elephants to drive their wild relatives from fields to natural habitat. "In one area of Assam [India], during the past dry season we had 200 of these drives, and groups of 4 or 5 elephants were able to move groups of 100 to 200 wild elephants," WWF's Dillon explained.
But such measures don't address the larger problem of increasingly shrinking and balkanized elephant habitat.
"Elephants are being squeezed out of their traditional areas," said the SEVP's Poole. "As less and less resources are available for wildlife, there will, inevitably, be conflicts. And with the current trends of rapidly increasing human population and little or no land-use planning, we can expect conflict to get worse before elephants are slowly eliminated, area by area."
But hope may lie with a different economic dynamic.
"In areas where communities benefit from elephant-related tourism, elephant habitat has more of a value," said Stanford's O'Connell-Rodwell. "This trend should be encouraged if elephants [are to] have a hope of surviving this war over the most basic resources: food, shelter, and water."