The sweet sounds, described in a study published in the journal Functional Ecology, were music to the ears of ecologists who were hoping to learn more about the first months of a humpback whale’s life.
“It is amazing to hear whales produce sounds underwater in an environment that is hard to access and is foreign to us,” lead author Simone Videsen of Aarhus University told Seeker. “It can only make you happy to hear these sounds produced by calves. The calls produced by the calves are very varied, and some of them sound like grunts while others are very squeaky.”
She added that the calves also produce rubbing sounds, “like two balloons being rubbed together,” which she and her colleagues suspect occurs when calves nudge their mother, signaling that they want to nurse.
Humpback whales are often on the move. They spend their summers in the food-rich waters of the Antarctic or Arctic before migrating 5,000 miles in the winter to the tropics in order to breed and mate. The moms and calves included in the study were located at Exmouth Gulf in the northwestern region of the state of Western Australia.
Perhaps the whales’ greatest challenge, however, is to stay in communication with each other without being overheard.
“Potential eavesdroppers could be killer whales that are known to prey upon humpback whale calves in the area,” Videsen explained. “These [predators] could use the communication between mother and calf as a homing cue.”
“Other potential listeners could be male humpback whales that want to mate with the mother, which would disrupt potential nursing time for the calf,” she added.
As the newborns whisper, the mothers appear to emit very quiet calls from time to time in response. The mothers have the ability to vocalize much louder, so the finding suggests that they are intentionally controlling the sound of their calls.
If the mothers and calves are intentionally lowering the strength of their vocalizations, that would suggest an extraordinary level of not only self-awareness, but also awareness of what others in the region could be capable of hearing. These skills could indicate a very high level of intelligence.
It has long been documented that loud man-made sounds, such as those produced by ships and military exercises, impact whales and other marine life. The determination that humpback whales whisper suggests that human-produced machinery sounds could be particularly harmful to calves and their mothers.
Read more at Discovery News