Parrots are not the only animals that could imitate human speech. In a new study, scientists found that killer whales are capable of mimicking sounds such as "hello" and "bye bye."

The team uncovered the animal's surprising characteristic by training and observing the progress of a 14-year-old female orca named Wikie. It currently resides in the Marineland Aquarium in Antibes, France, with her 3-year-old offspring Moana.

Unlike its undomesticated counterparts in the wild, Wikie has been trained to obey and follow the sound of simple commands. This time, scientists decided to take their research further by introducing sounds the creature has never heard of before.

How Scientists Trained An Orca To Copy Sounds

At first, Wikie was made to listen to 278 new inputs coming from both human and whales.

Based on recordings obtained using a specialized device embedded inside the animal's body, scientists identified 11 distinct sounds produced by the orca. Though impressive, they were considered invaluable, as none matched any of the 278 sounds.

Next, the trainers used a more systematic approach. Wikie was initially trained to imitate three familiar sounds produced by Moana, followed by five new sounds from other killer whales.

It was then exposed to a human trainer copying three of the novel orca sounds and uttering six simple human words including "hello," "Amy," "ah ha," "one, two," and "bye bye."

In all structured trials, six observers noted that Wikie was able to successfully mimic all input while its head was above the water's surface and its blowhole exposed to the air.

With these results, scientists have concluded that killer whales could "control sound production," therefore qualifying them as "open-ended vocal learners," or creatures that could learn and copy sounds throughout their lifetime.

Moana's participation in the experiment has also led to a new theory that young calves learn to create sounds the same way human children do, by mimicking the elderly around them.

What Enables Killer Whales To Imitate Sounds?

Orcas are among the few mammals that are known to copy specific sound input. However, it remains unclear to scientists as to how these creatures were able to develop the ability.

In the study, scientists have theorized that this ability could be traits that modern orcas have inherited from their terrestrial ancestors. Such trait then became more refined as the species adapted to its aquatic environment where its sound-producing organs are compressed by changes in pressure. However, scientists have another theory.

"It could mean that cultural differences like dialects can drive the evolution of the species, as we see between ecologically divergent killer whale populations that have resulted in sufficient reproductive isolation despite sympatry to lead to incipient speciation," says the study's lead author José Abramson of Universidad Católica de Chile.

The study only deals with the killer whale's ability to reproduce sounds. It does not investigate whether orcas could understand the context of human statements they are exposed to.