Two years ago, scientists showed that dolphins imitate the sounds of whales. Now, it seems, whales have returned the favor. Researchers analyzed the vocal repertoires of 10 captive orcas (Orcinus orca), three of which lived with bottlenose dolphins (Tursiops truncatus) and the rest with their own kind. Of the 1551 vocalizations these seven latter orcas made, more than 95% were the typical pulsed calls of killer whales. In contrast, the three orcas that had only dolphins as pals busily whistled and emitted dolphinlike click trains and terminal buzzes, the scientists report in the October issue of The Journal of the Acoustical Society of America. (Watch a video as bioacoustician and co-author Ann Bowles describes the difference between killer whale and bottlenose dolphin whistles.) The findings make orcas one of the few species of animals that, like humans, is capable of vocal learning—a talent considered a key underpinning of language.

*Correction, 8 October, 2:24 p.m.: In the video, Ann Bowles describes the difference between killer whale and bottlenose dolphin whistles, not killer whale and orca whistles, as was previously reported.