Humpback whales might be expected to take their food seriously given their enormous size, but a new study shows that they may multi-task as they eat, singing mating or breeding songs as they forage in their Antarctic feeding grounds. The research, published December 19 in the open-access journal PLOS ONE by Alison Stimpert from the Naval Postgraduate School and colleagues, sheds new light on the whales' singing habits in different seasons, which are still a mystery.
Whales sing most frequently during the breeding season but are known to sing on other occasions, such as while escorting mother-calf pairs along migratory routes. Though the reasons that whales sing are still unknown, the distinction between their seasonal behaviors is clear. Breeding, migration and foraging occur in different regions and times of the year, and rarely overlap.
In the current study, the researchers tracked ten whales to study singing behavior in their foraging grounds. They found that all ten sang while foraging, but two of the whales showed intense, continuous bouts of singing similar to what the researchers expected to see in breeding grounds. They also found the whales sang for up to an hour at a time and during active diving periods.
According to the authors, their data reveal a previously unknown behavioral flexibility, where humpbacks can balance the competing needs to feed continuously to prepare for breeding with mating behaviors like song displays. They suggest that this may also signify an ability to engage in breeding activities outside of the traditional, warm water breeding ground locations. Stimpert adds, "We were surprised to find such structured song in the Antarctic feeding ground. The tag data are also exciting because this is the first time that we can see that the singers aren't sitting off by themselves like they do on the breeding grounds -- they're right in the midst of the feeding action, choosing to sing instead."