Do Disney's Real Elephants Have Tales to Tell?
National Geographic News
|February 21, 2003|
Elephants communicate with one another in a number of ways, including sound, sight, touch, and scent. But it is the noises they makea repertoire of rumbles, roars, trumpets, bellows, cries, screams, and snorts that spans almost ten octaves, including sounds that humans cannot hearthat scientists find the most challenging to comprehend.
Researchers have been eavesdropping on wild elephants in Africa for years (please see sidebar).
The work continues in Africa today with the Savanna Elephant Vocalization Project and the Amboseli Elephant Research Projectundertakings that have collected more than 70 different elephant call types, linked them to observations of elephant behavior, and which are now being made available to the entire scientific community and the public through a database freely accessible on the World Wide Web. (Please read our story on the Savanna Elephant Vocalization Project.)
But it is not only in the forests and plains of Africa that researchers are tuning in to elephant "talk." The work is also being done in zoos, where scientists are hoping that what they learn from listening to animals in captivity can extend the knowledge learned in the wild.
Scientists at Disney's Animal Kingdom, Lake Buena Vista, Florida, are making a contribution to understanding elephant vocalizations in a study designed by a team of researchers with the help of the theme park's "Imagineers."
The Animal Kingdom's Wildlife Tracking Center is leading a project that focuses on how elephants communicate in captivity.
The work builds on the use of wireless microphones created by William Langbauer and a real rocket scientistSteve Powell of the Cornell Space Sciences Programfor use in Africa, as well as on the work of many scientists who have studied the acoustic and chemical cues associated with elephant reproduction.
"We had Disney engineers and Imagineers design special radio-transmitting collars that the elephants could wear comfortably and unobtrusively," said Anne Savage, conservation biologist at Animal Kingdom. "Inside these collars are microphones that pick up the sounds elephants make and transmit them back to our conservation station where they are recorded and analyzed on computers. Each collar has a different frequency so we can switch back and forth and listen to different elephants."
Since the Animal Kingdom opened its doors to the public in 1998, researchers have been listening in on seven female and three male African elephants. The theme park is particularly interested in studying vocalizations and visual communication with regard to reproduction. "We listen and watch what happens when it's just the females present, then we monitor what happens when the males are present," Savage said.
The information might allow the researchers to glean valuable information about elephant reproductive strategiessomething which is obviously useful for keepers of elephants in captivity but which might also be valuable when compared with observations of the vocalizations and behavior of elephants in the wild.
Information gathered by the team is shared with the research community both in Africa and at zoos.
The Animal Kingdom team has devised eight broad categories of elephant calls, based on how the sounds can be grouped acoustically (please see the image caption for links to audio files of these sounds).
"We have the technology to compare all the different [noises] and match them to individuals," said Kirsten Leong, an Animal Kingdom researcher. "We are looking at every call they make and look at whether the repertoire can be broken down acoustically and not only according to what the elephants are doing."
"Eighty to 90 percent of our recordings are of rumbles," Leong said. "We find the elephants also use them when they are interacting at very close distances."
Through regular blood tests to monitor hormone levels, the researchers have been trying to track if vocalizations change over the elephant's reproductive cycle. "We are looking at how vocalizations might be used as a signal to the male, and possibly other females, to advertise their fertility," said Savage.
In the wild, elephants generally live in groups segregated by gender. Adult male elephants are generally solitary or associate with other bulls in loose associations while females live in families. During sexually active periods, known as musth, males spend much of their time searching for mates. Adult males only enter female herds temporarily for mating.
"Given that males and female herds are separated by several miles, how do males know when females are in estrus? We are looking at how female elephants signal to males their impending fertility," Savage said.
Bulls Always Looking for Mates
Researchers in Africa have observed that bulls are always looking for mates, using smell and hearing to seek out particularly females in estrus.
"In a 16-week cycle, females are fertile for only two or three days, a maximum of four times each year," Leong said. "Most of the time in the wild elephants do become pregnantso realistically between pregnancies it is generally four or five years before they will ovulate again. How do the elephants find a mate when the window of opportunity is so small? It is believed that females must be advertising with vocalizations, and that that males are hearing this from far away."
Vocalization with infrasonic components is how elephants make long-distance calls. The very low-frequency sound that humans cannot hear can be heard by other elephants across great distanceshumans in proximity to the elephants hear the upper frequencies of these powerful calls. Researchers in Africa have found evidence that elephants can identify up to a hundred individual voices from more than a mile awayand there are suggestions that elephants might be able to communicate over distances upwards of 20 miles (32 kilometers) by making the ground vibrate.
The ability to communicate over long distances could mean that males can monitor different female herds at the same time, listening in to groups near and far and moving in whenever they hear a female that sounds like she is ready for mating.
"We've monitored changes in vocalizations when a female is getting ready to ovulate," Leong said. "Although many of the vocalizations appear to be related to changes in female-to-female interactions, males could easily gain information by eavesdropping on these vocal exchanges from far away."
Researchers at the Animal Kingdom have noticed that when a male joins the female herd there is no special vocalization within the group. Instead, the male shows more than usual interest in the females by performing a lot of genital inspections with his trunk. "It turns out that when the male is right there they don't talk about it," Leong said.
Observations in the wild have indicated that females may show indifference to a young male but become audibly excited when a musth male shows up, often rumbling in a group in behavior known as the "female chorus."
The Animal Kingdom project is small in that it is focused on a tiny herd of elephants in a relatively confined space (although by zoo standards their enclosure is impressivea "savanna" of many acres landscaped to approximate grasslands, forests, rivers, and hills). But the Disney scientists believe they have some unique advantages in that they can pinpoint the vocalization of not only each individual as it emits the sound but also monitor any response and ensuing "conversation."
A zoo project like the Animal Kingdom's provides a comparison of vocalization of animals in captivity with that of elephants in the wild. Knowledge gained from elephants born and living in captivity can help those remaining in the wildwhile the work in Africa allows zookeepers to gain a better understanding for breeding and caring of animals in their care.
"We're using our elephants to do what we can to protect the elephants in the wild," said Savage. "It's not just the research, of course, but how the millions of visitors to Disney's Animal Kingdom react to them and our work with them. Awareness of these great animals and how they communicate helps people appreciate them and understand why it is important to protect them in the wild."
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