Researchers at the San Diego Zoo's Wild Animal Park are studying African elephants' calls to each other. The adult females are particularly vocal, making certain types of calls to their "sisters" in the herd while they're pregnant, then a different set of calls to their calves once they're born. (Photo by Jamie Scott Lytle - Staff Photographer)
They're huge, they walk on four legs, and they stuff food into their mouths with their trunks. Like humans, though, they like to hang out together and "talk."
Someone is watching and listening when they do.
And it didn't take that someone long to discover that female African elephants in a herd at the San Diego Zoo's Wild Animal Park talk a heck of a lot more than anyone realized.
Dr. Matt Anderson, the park's acting director of behavioral biology, has been recording eight of the elephants' vocalizations for one 24-hour period per week for about 10 weeks, then overlaying the sounds with information about their movements and behavior.
He said last week that the project is already producing big surprises: Female elephants tend to be chatterboxes and their ranking in the herd plays a role in how vocal and active they are.
He said he also discovered that a low rumbling call ---- which researchers thought females used only to tell faraway males they were ready to mate ---- is also used among themselves.
And although it was well known that females form a protective circle around a pregnant mother giving birth, Anderson said no one realized the mother actually tells the group when the baby is coming ---- knowledge that could help keepers prepare for the births of calves.
"It's essentially a secret language," he said, adding that the study has also revealed specific types of calls from the mothers to their calves. "It falls very low in the sound spectrum. ... And we're now able to capture it."
Because African elephants are more likely to breed successfully when they are in a natural habitat and stress-free, Anderson said, the information may help researchers understand how environment affects pachyderm hormones and communication, leading to more breeding success.
Natural opportunity
The ability of animals to communicate with one another is well known and, in some cases, well-documented. Cheetahs, gibbon apes and koalas are among the more familiar animals researchers have studied both in the wild and in zoos.
Some elephant "talk" has also been recorded. And Anderson, who has been at the park for nearly six years, has another project going in Botswana, where he is using GPS devices to track the movements of pachyderms in the wild.
He said this is the first time, however, that anyone has recorded the animals over a 24-hour period and correlated the results with information about the elephants' behavior and movements.
The park's natural setting and "wonderful" herd of African elephants present the perfect opportunity for studying their movements and sounds, he said.
Run by the Zoological Society of San Diego, the park is spread over 1,800 acres in the hills east of Escondido. The park was designed to be an endangered animal breeding and research center for the world-renowned San Diego Zoo, which the society also runs. But strong public interest prompted zoo officials to open the park to guests upon its completion in 1972.
Park inhabitants roam large enclosures modeled after the native habitats of the large variety of animals.
Most of the park's African elephants are part of a herd the Zoological Society helped bring to the United States from a Swaziland nature preserve in 2003. Several calves born since then have increased the herd's size to 13.
Potential breeding aid
Anderson and park research coordinator Dr. Lance Miller teamed up for the recording project, which is being paid for with money from several grants, donations and the Zoological Society's research budget.
Miller focused on developing special $2,500 leather collars equipped with a chin microphone, a GPS tracking system and a recording device. Anderson said that although everyone involved expected the animals to be wary of the collars at first, they were more curious than afraid and accepted their new accessories relatively quickly after keepers introduced them.
Before his experiment, Anderson said, it was well known that elephants used a handful of calls and other sounds ---- including the rumble and what he calls "the 'Jungle Book' trumpet call" ---- to communicate.
Many animals also make high- and low-frequency sounds inaudible to the human ear.
Specialized computer software that speeds up the recordings and graphs the vocalizations revealed just how much communication was going on within the elephant herd, Anderson said.
He said he combined the information with the GPS data and detailed observations of the elephants' behavior during the recording sessions to put the sounds into context.
"That tells you what they're saying," Anderson said. "It's very exciting. We thought that they had a certain vocabulary, but we're finding it's much larger than anyone realized."
He said he is cataloging the results in a growing audio "dictionary" of elephant sounds.
Dr. Allison Alberts, chief conservation officer for the San Diego Zoo, said officials there and at similar facilities welcome the new data that the project is producing.
"We are very excited about this intriguing research and its potential to help us better care for elephants in zoos and conserve them in the wild," she said. "It provides important insights into elephant behavior that we otherwise would not be able to gather."
Call staff writer Andrea Moss at 760-739-6654.
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