Right Whales May Boast Unique Voices

Scientists are just beginning to understand how whales produce sound, and now new research suggests that like humans, North Atlantic right whales boast unique individual voices.

It is common for us to recognize different people based solely on the way they sound - for example, the resonating bass of James Earl Jones is easily distinguished from the nasal laugh of actress Fran Drescher. This idea has recently been applied to other members of the animal kingdom, including dogs and deer. And now, a team from Syracuse University is working to apply the theory of individually distinctive vocal characteristics to North Atlantic right whales.

As an endangered species, this research could potentially be used to identify and track individuals and improve conservation efforts for right whales.

During the study, scientists were able to correctly distinguish 13 different individual whales based on a combination of vocal characteristics, including length of the calls and the fundamental and harmonic frequencies.

Right whales make about a half-dozen different types of calls, but the Syracuse team focused on the characteristics of the "upcall" - a vocalization that lasts about 1-2 seconds and rises in frequency from around 100 Hz to 400 Hz, at the low end of frequencies audible to human ears. The upcall is the most commonly produced call among all ages and sexes of right whales, and is likely used to announce their presence and "touch base" with other whales.

Based on the characteristics that distinguish human voices, the researchers thought the emphasized harmonic frequencies of the upcalls, called formants, would best distinguish individual whales.

"What I found was that there actually wasn't much difference in the formants, but one of the variables that came out as most important in discriminating the individuals was the duration of the call," researcher Jessica McCordic said in a statement.

In the end, the team found that analyzing a combination of variables, including the formant, the duration of the calls, and the rate of the fundamental frequency change, could distinguish between the upcalls of the 13 individual whales identified in the archival data set.

For centuries, humans have hunted North Atlantic right whales - which feed on tiny zooplankton in shallow waters off the east coast of the United States and Canada. Now, this marine species is listed as critically endangered, with population numbers estimated at around 450 whales.

But by better understanding their unique voices, scientists may be able to improve tracking of these whales, which spend most of their time under water. This could bolster conservation efforts and help the species on its road to recovery.

The team will present their results at the 169th meeting of the Acoustical Society of America, held May 18-22, 2015 in Pittsburgh.

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