Big mimics: African elephants can learn to copy sounds.

Two captive elephants--one making truck noises and the other chirping like a different elephant species--could be the first nonprimate, land mammals demonstrated to do vocal imitations.

"It is certainly a surprise to most people, even those who know elephants," says Joyce Poole, research director of the Amboseli Elephant Research Project headquartered in Sandefjord, Norway.

Poole, who has studied elephant communication for years, documented one case of imitation after a friend raising an orphan African elephant told her of an odd noise that it made. When Poole visited the orphanage in Tsavo, Kenya, she recorded a low-pitched sound that the adolescent female Mlaika made for several hours after sunset. The night stockade for the elephants stood 3 kilometers from the Nairobi-Mombasa highway, and Poole says that while recording calls and traffic noise, "I sometimes couldn't distinguish the sounds of the trucks from Mlaika calling."

Poole then heard about another unusual vocalization, this one from a 23-year-old male African elephant that spent 18 years with two Asian elephants in a Swiss zoo. He routinely made chirpy calls, typical for his Asian companions but not for his own species.

Poole got in touch with Peter Tyack, who specializes in vocal learning among marine mammals. Tyack's team at Woods Hole (Mass.) Oceanographic Institution made statistical comparisons of each of the alleged imitations, the elephants' other vocalizations, and the sounds that the animals seemed to be mimicking. The analysis confirmed the imitation, Poole, Tyack, and their collaborators report in the March 24 Nature.

The researchers point out that African elephants live complex social lives, as do the other animals known to learn vocalizations--primates, some marine mammals, bats, and birds. Vocal learning may be important for such a lifestyle.

Poole predicts that Asian elephants will also turn out to have powers of mimicry. As the researchers were preparing their paper, she says, they found an article published many years ago in the Journal of the Bombay Natural History Society. An older Asian elephant could hold her trunk at a particular angle and blow through it to whistle. A younger one watched, touched the outstretched trunk, and eventually picked up the knack.

"I was so excited by [the Poole-Tyack team's] ability to document the mimicking phenomenon because we had suspected it for some time in our own elephant-vocalization studies," comments Caitlin O'Connell-Rodwell of the department of otolaryngology at Stanford Medical School, where she does research on elephant communication. She says that she's wondered whether some calls she's heard were attempts to mimic the non-elephant noises she'd played as part of certain experiments.

"The next step," says Poole, "is to look at how elephants use vocal learning in the wild."