Imagine traveling thousands of miles with your newborn in search of food. Now imagine doing this in almost complete darkness. This is exactly what humpback whales and their newborns do as a matter of routine. The journey to the food-rich Antarctic or Arctic waters from their tropical breeding grounds can be thousands of miles. The mother and calf swim in deep ocean waters where light is scarce and therefore vision is not very useful. The pair has to depend on sound to keep track of each other. But broadcasting their presence to killer whales can be fatal.
Scientists at the University of Aarhus have recently uncovered the mystery of how this journey is accomplished in stealth and safety. It turns out that the calves and their mothers “whisper” to each other. The scientists recorded the communication between the mother and calf through sensors attached to the calves using suction cups. The sensors were designed to fall off after 48 hours of recording and float to the surface. These soft grunts are distinct from the well-known and characteristically loud whale songs. Perhaps designed for communication with the nearby mother and inaudible to predators. The sensors also recorded rubbing noises suggestive of body contact between the mother and the calf as another means of literally staying in touch. The ingenuity of nature!
Videsen S, Bejder L, Johnson M, Madsen P. (2017) High suckling rates and acoustic crypsis of humpback whale neonates maximize potential for mother-calf energy transfer. Functional Ecology April 25.