Culling has long been used as a conservation tool to keep elephant populations in check, but a new study shows such killings can psychologically damage groups of elephants for decades.
Wildlife officials in South Africa have used culling to manage elephant populations since the 1960s. The environmental benefit is clear: too many of these huge, hungry animals could quickly eat, trample and uproot the vegetation in a fenced nature reserve. To prevent such habitat destruction, managers have historically rounded up the big beasts with a helicopter and had professional hunters on the ground kill some adults. The young elephants are then shipped to other parks.
PTSD for Elephants
Previous studies have shown that young elephants that live through such events grew up with a version of PTSD, delaying their development and making them unusually scared or aggressive. The elephants in this study had experienced even more extreme distress, however, as one of the researchers, Joyce Poole, told National Geographic,
"These calves watched as their mothers and other family members were killed and butchered. Because the people in charge of culls didn't understand the long-term implications, didn't understand they were dealing with intelligent, highly social animals, they, for convenience, tied the calves to their dead mothers while the butchering took place."
The practice of culling was stopped over a decade ago, and from the outside, these now-adult elephants seem to be doing okay. But researchers wanted to know if the effects of these events were lasting.
Looking Long Term
Scientists looked at the social dynamics of two elephant populations: one in Kenya that was relatively undisturbed by culling and a second in South Africa which was made up of orphans brought there in the '80s and '90s after the mass killing described above. The scientists videotaped the elephant families' reactions to recordings of different elephant calls
---some familiar and friendly voices, and some older, dominant strangers (which posed potential threats). For the Kenyan elephants, responses were consistent and coordinated: When the enemy call was broadcast, everybody froze to listen and then packed tightly together with the matriarch out front for protection. With the South African elephants, though, there was no pattern. No one knew what to do, so they sometimes fled from friendly calls and stayed calmly in place during threatening calls. Such random and unpredictable responses could put the families in real danger, according to the study
published in Frontiers in Zoology. Since the orphaned South African elephants grew up without role models to teach them how to behave or interact with one another, researchers believe their societies function less well, even today. And in a species as smart and social as elephants, the effects of such a lack of tutelage can be devastating. Behavioral ecologist Karen McComb, another of the researchers, told Science Now
,
“On the surface, they look like they’re now getting on okay. But we found a way to go deeper into their minds, and that’s how we found the deficits in the social decisions that they make.”
[For more on endangered elephants, check out Discover's recent feature, Caught in the Crossfire, and the photo gallery that goes with it, Life Among Africa's Endangered Forest Elephants.]
Image credit: Stacey Ann Alberts/Shutterstock
