If you needed any additional evidence of how smart orcas or killer whales are (and dolphins in general--killer whales are the largest dolphin species) look no further.
In the video below, a killer whale approaches a boat and begins to make a series of sounds that can't be anything other than the whale mimicking the sound of the boat motor.
UPDATE: This whale is the subject of a film called The Whale that is showing in select cities across the country that explores the issues surrounding human-whale contact. Video below by Suzanne Chisholm.
This shouldn't come as much of a surprise given that these animals live in complex social groups and have different behaviors depending on their dietary choices (some eat fish, some penguins, and some eat other marine mammals). Different family groups even have different dialects that they use to communicate with each other.
While odd to hear, if you think about it, the fact that such an intelligent animal can mimic the sound of a boat motor isn't so surprising. It's probably pretty simple compared to the brain work that they have to do in order to survive in the wild. Check out these killer whales working as a coordinated team to dislodge a seal off an ice floe - now that's some smarts!
Learn more about Killer Whales from Animal Planet!
Adopt a killer whale with the National Wildlife Federation.