Under poaching pressure, elephants are evolving to lose their tusks

THE OLDEST ELEPHANTS wandering Mozambique’s Gorongosa National Park bear the indelible markings of the civil war that gripped the country for 15 years: Many are tuskless. They’re the lone survivors of a conflict that killed about 90 percent of these beleaguered animals, slaughtered for ivory to finance weapons and for meat to feed the fighters.

Hunting gave elephants that didn’t grow tusks a biological advantage in Gorongosa. Recent figures suggest that about a third of younger females—the generation born after the war ended in 1992—never developed tusks. Normally, tusklessness would occur only in about 2 to 4 percent of female African elephants.

Decades ago, some 4,000 elephants lived in Gorongosa, says Joyce Poole—an elephant behavior expert and National Geographic Explorer who studies the park’s pachyderms. But those numbers dwindled to triple digits following the civil war. New, as yet unpublished, research she’s compiled indicates that of the 200 known adult females, 51 percent of those that survived the war—animals 25 years or older—are tuskless. And 32 percent of the female elephants born since the war are tuskless.

A male elephant’s tusks are bigger and heavier than those of a female of the same age, says Poole, who serves as scientific director of a nonprofit called ElephantVoices. “But once there’s been heavy poaching pressure on a population, then the poachers start to focus on the older females as well,” she explains. “Over time, with the older age population, you start to get this really higher proportion of tuskless females.”

This tuskless trend isn’t limited to Mozambique, either. Other countries with a history of substantial ivory poaching also see similar shifts among female survivors and their daughters. In South Africa, the effect has been particularly extreme—fully 98 percent of the 174 females in Addo Elephant National Park were reportedly tuskless in the early 2000s.

“The prevalence of tusklessness in Addo is truly remarkable and underscores the fact that high levels of poaching pressure can do more than just remove individuals from a population,” says Ryan Long, a behavioral ecologist at the University of Idaho and a National Geographic Explorer. The “consequences of such dramatic changes in elephant populations are only just beginning to be explored.”

Josephine Smit, who studies elephant behavior as a researcher with the Southern Tanzania Elephant Program, says that among the female elephants she tracks at Ruaha National Park, an area that was heavily poached in the 1970s and 1980s, 21 percent of females older than five are tuskless. As in Gorongosa, the numbers are highest among older females. About 35 percent of females older than 25 are tuskless, she says. And among elephants ages five to 25, 13 percent of females are tuskless. (Smit, a doctoral candidate at the University of Stirling, in Scotland, says the data have not yet been published, though she presented the findings at a scientific wildlife conference last December.)

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