Do Whales Think They're Dolphins?

Apparently whales now think they're dolphins. New research demonstrates vocal learning in killer whales, which have used the talent to copy noises of bottlenose dolphins and apply them in appropriate social contexts.

Animals make all sorts of sounds, from gobbles and coos to barks and quacks. And while each has its own distinctive sound, some species - humans included - have developed a talent for imitating new noises. Killer whales, it seems, are one species that dabbles in this type of mimicry.

Researchers found that when killer whales (Orcinus orca) mingled with bottlenose dolphins, they shifted the types of sounds they made to more closely match their social partners. Vocal learning, as its known, has also been observed in bats, some birds, and cetaceans, which includes whales and dolphins. But studying the neural pathways behind the imitation is more difficult in large marine animals.

Killer whales have complex vocal repertoires made up of clicks, whistles and pulsed calls - repeated brief bursts of sound punctuated with silence. And like humans, whales have different dialects based on their varying acoustic features, such as their duration, pitch and pulse pattern.

"There's been an idea for a long time that killer whales learn their dialect, but it isn't enough to say they all have different dialects so therefore they learn. There needs to be some experimental proof so you can say how well they learn and what context promotes learning," senior scientist Dr. Ann Bowles said in a statement.

Bowles and her team decided to study old recordings of vocalization patterns from the cetaceans, and compare them with those of whales that had socialized with bottlenose dolphins. They found that all three killer whales that had been housed with dolphins for several years shifted their vocal range to more closely resemble that of a dolphin's. Specifically, they produced more clicks and whistles and fewer pulsed calls.

What's more, the researchers discovered that killer whales can even produce entirely new sounds. One whale learned to produce a chirp sequence that human caretakers had taught to its dolphin poolmates.

"Killer whales seem to be really motivated to match the features of their social partners," Bowles added.

Bowles and colleagues suspect that this form of flattery, so to speak, will be useful amidst climate change, where whales may need to adapt their communication strategies in accordance with shifting social groups and territories as oceans warm.

The findings were published in The Journal of the Acoustical Society of America.