Researchers from Aarhus University in Denmark may have discovered the way baby humpback whales stay safe from predators. The recordings, published in the journal Functional Ecology say the calves whisper to their mothers to avoid being hunted. Using recording devices attached to the baby humpback whales, researchers were able to record their grunts and squeaks.
Humpback whales are a species of baleen whales. When the calves are born, they are just over 16 feet long. When fully grown, a humpback whale can range in size from 39 to 52 feet long and weigh nearly 80,000 pounds. With a distinctive body shape, humpback whales are often seen breaching the ocean waters, making them a favorite sight for whale watchers. Males of the species can produce a song lasting 10 to 20 minutes, repeating for hours. They are found in oceans and seas all over the world and migrate up to 16,000 miles annually. Humpback whales breed and give birth in tropical or subtropical waters and travel to feed in the food-rich polar waters. With a diet of mostly krill and small fish, the whales are unfortunately a target for the whaling industry.
According to NPR, the calves travel with their mothers halfway around the world during their annual migration. Simone Videsen, a researcher at Aarhus University and author of the study, said that the “early life stages of wild whales are so elusive because they’re an aquatic animal.” The team of researchers tracked eight baby humpback whales using “special sound and movement recorders.” They are attached to the whales by suction cups where the equipment can stay there for “about a day” before falling off. The BBC reported that this was the first time that this type of communication was recorded and heard.
The squeaks and grunts made by the baby humpback whales turned out to be different from the familiar and traditional whale songs created by adult whales. Videsen, speaking to NPR, said that the recordings were “squeaky” and some of them were like “grunting sounds.” The study, published in Functional Ecology, said that some of the vocalizations between mother and calf included “very weak tonal and grunting sounds,” that the calf made while diving rather than while suckling. This suggested to the researchers that “mechanical stimuli rather than acoustic cues are used to initiate nursing.”
Another surprising fact, the researchers found, was that the sounds made by the babies were “very quiet” almost like they were “whispering” to not be overheard by predators. Videsen went on to say that the sounds were like “homing cues” for mother and baby. Most likely, the researchers theorized, the mother humpback whales used the sounds to help track of their calves. Speaking to The Guardian, Videsen, said that the mother and calf did not want any “unwanted listeners.”
By Cheryl Werber
Photo Courtesy Jean Tresfon