From elephants to bats, kangaroos to sea lions, mammals are a diverse class of animals. But what binds them all together is their ability to produce milk, which females of the species can use to nurse their young. Unsurprisingly, observing this behavior in ocean-dwelling mammals is a lot harder than of those on land. However, researchers from the University of Hawai’i at Mānoa’s Marine Mammal Research Program (MMRP) have been able to capture some incredible footage of humpback whales nursing their calves.
Every winter, around 10,000 humpbacks make the 4,800-kilometer (3,000-mile) journey from their rich feeding grounds in Alaska to the warm and relatively protected waters in Hawaii for breeding. In order to better document the species’ behavior at this time, the MMRP teamed up with the Goldbogen Lab at Stanford University’s Hopkins Marine Station and the Friedlander Lab at the University of California, Santa Cruz, to track calves earlier this year.
(NOAA permit #21476)
Off the coast of Hawaii in the Maui breeding ground, they deployed non-invasive suction cup tags onto seven humpback whale calves. With acoustic recorders, depth sensors, and accelerometers, the tags provided lucrative data for the team on the movement and breathing patterns of the tagged whales. But perhaps the most exciting part was the built-in cameras.
Providing researchers with a whale’s-eye view, the “whale-cams” captured moments when baby whales retrieved milk from their mother’s feeding glands, whilst fish gathered around to slurp up the offshoots. Although the footage only covered between 5 and 20 hours of data per humpback calf, the young will continue to breastfeed for most of the first year of their lives. Broadly speaking, these videos will help the team to quantify the nursing behavior of humpback whales (i.e. nursing bout frequency and durations).
“We can actually see what these animals are seeing and encountering and experiencing themselves,” MMRP Director Lars Bejder said in a statement. “It’s quite unique and rare footage that we’re obtaining, which is allowing us to quantify these nursing and suckling bouts that are so important.”
As well as deploying whale-cams, the team used drones to gather more data on the length, body condition, and health of the humpback calves, which when fully grown can weigh up to 36 metric tons and measure between 14.6 and 19.1 meters (48 to 62.5 feet).
Bejder and his team are no strangers to capturing rare and adorable humpback whale videos. During last year’s breeding season, they filmed a newborn only minutes after it entered the world. Up in Southeast Alaska, during the feeding season, they also recorded ground-breaking footage of humpback whales during what is known as bubble-net feeding.
As humpback whales don’t feed whilst breeding, they rely on energy stores gained from the feeding season. Not only does a healthy supply matter for the mothers, but the calves also need her stores to survive and become strong enough to migrate back up to their summer foraging grounds. Therefore, the interplay between these two facets of the MMRP’s research will provide a rounded insight into humpback whale breeding.
“Combining these data sets across the foraging and the breeding grounds is really going to tell us something about the importance of these different habitats for these animals,” Bejder said.