sciencetech-blog

comments

Most animals make noises that are innate, not learned.

But scientists claim killer whales can learn to 'talk' like dolphins when the two species spend time together. 

This means the ocean predators join the likes of bats, some birds and humans that each copy sounds and use them in appropriate social contexts. 

Killer linguists? Scientists claim killer whales (pictured) learn to 'talk' like dolphins when they spend time together, joining species such as bats, some birds and humans that can copy sounds and use them in appropriate social contexts

They found that orcas can engage in cross-species 'vocal learning' by matching the types of sounds made by bottlenose dolphins when spending time with them.

The results, published in The Journal of the Acoustical Society of America, suggest that vocal imitation may enable social interactions in cetaceans.

Killer whales have complex vocal repertoires made up of clicks, whistles and pulsed calls, which are repeated brief bursts of sound punctuated with silence.

The acoustic features of the vocalisations - such as their duration, pitch and pulse pattern - vary across social groups.

Whales that are closely related or live together produce similar pulsed calls that carry vocal characteristics distinct to the group, known as a dialect.

'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,' said senior research scientist Ann Bowles, of Hubbs-SeaWorld Research Institute in San Diego, California.

'There needs to be some experimental proof so you can say how well they learn and what context promotes learning.'

Testing vocal learning ability in social mammals usually requires observation of an animal in a social situation that might stimulate it to communicate in new ways.

Experts have found that orcas can engage in cross-species 'vocal learning' by matching the types of sounds made by bottlenose dolphins (pictured) when spending time with them

Dr Bowles said bottlenose dolphins provide a useful comparison species as they make generally similar sounds but produce them in different proportions, relying more on clicks and whistles than the pulsed calls that dominate killer whale communication.

She said: 'We had a perfect opportunity because historically, some killer whales have been held with bottlenose dolphins.'

By comparing old recordings of vocalisation patterns from the cross-socialised subjects with recordings of killer whales and bottlenose dolphins housed in same-species groups, Dr Bowles and her team were able to evaluate the degree to which killer whales learned vocalisation patterns from their cross-species social partners.

She said all three killer whales that had been housed with dolphins for several years shifted the proportions of different call types in their repertoire to more closely match the distribution found in dolphins. This means that they produced more clicks and whistles and fewer pulsed calls.

The researchers also found evidence that killer whales can learn completely new sounds.

One killer whale that was living with dolphins at the time of the experiment learned to produce a chirp sequence that human caretakers had taught to her dolphin pool-mates before she was introduced to them.

Dr Bowles said vocal learning skills alone don't necessarily mean that killer whales use language in the same way that humans do. However, they do indicate a high level of neural plasticity - the ability to change circuits in the brain to incorporate new information.

She said: 'Killer whales seem to be really motivated to match the features of their social partners.

'It's important to understand how they acquire their vocalisation patterns, and lifelong, to what degree they can change it, because there are a number of different cetacean populations on the decline right now.'