Nov. 17, 2006 — It may not be language as we know it, but whales have no shortage of ways to make themselves understood.
So broad is their vocal repertoire, in fact, that whales can call to their young, woo potential mates and even express emotions, according to researchers who have identified 622 social sounds in humpback whales.
Their work will be presented at the upcoming joint meetings of the Acoustical Society of America (ASA) and the Acoustical Society of Japan in Hawaii.
Social sounds are brief, unpatterned sounds that are distinct from lengthier, complex whale songs. The new research adds to a growing body of evidence that whales convey more meaning through vocalizations than previously thought.
"I wouldn't say (whales possess) language, as that's a human term," Rebecca Dunlop told Discovery News. Dunlop, who worked on the study, is a researcher in the School of Veterinary Sciences at the University of Queensland, Australia.
"Whales don't string these sounds together like words and form sentences. It's more like a simple vocabulary," she said.
The scientists visually tracked 60 pods of whales migrating along the east coast of Australia. The researchers used a static hydrophone array — sensitive equipment that detects sound waves — linking the whale sounds to various activities and contexts.
They identified 622 distinct sounds, which fell into 35 basic types. These include "wops" made by females, "thwops" made by males, "yaps" made when pods split, and high pitched cries that appeared to express anger.
In addition to vocalizations, the researchers found that whales send messages through body language — by breaching the surface, slapping water with their tails and blowing underwater bubbles.
Famous for their long, complex songs, whales also sometimes "speak" short song units individually instead of singing them. Males especially seem to do this when trying to woo a female.
"Song is a loud broadcast signal and two singers singing at the same time is bound to be confusing to the receiver," Dunlop speculated. "If he's trying to attract a female, but doesn't want his signal confused with another singer in the area, then using song units in this case might be the way forward."
She thinks one reason whales are so vocal is because sound travels better in water than light, and so sight is less useful to whales than hearing.
Christopher Clark, director of the Bioacoustics Research Program at Cornell University, conducted a similar study on right whales.
He pointed out the irony that just as researchers are gaining a better understanding of whale vocalizations, humans are creating so much ocean noise — through shipping, oil and gas exploration, recreational traffic and more — that we often prevent whales from communicating.
"Many whales have very traditional feeding grounds and their migratory routes occur along shallow coastlines, which are now some of the noisiest, most heavily impacted habitats," he said.
"The ocean area over which a whale can communicate and listen today has shriveled down to a small fraction of what it was less than a century ago."