Humpback Bubble Feeding And The Importance Of Animal Culture

Humpbacks are high on my list of fascinating animals, in part because of this sort of spectacular and complex behavior, filmed by drone in Alaska’s Prince William Sound:

For the uninitiated, I09 describes what is going on:

Typically, humpback whales lunge into a shoal of prey, but as described in Arkive, they also herd their prey using a “bubble net” to trap them in quantity:

During this process, a number of whales will circle underwater emitting a continuous stream of air which traps fish in the centre of the ring, the whales then surface up through their ‘net’ gorging on the contents within. During the summer months, humpbacks must feed intensely as they do not feed again during either the migration or the time spent in tropical breeding grounds.

The fact that many species have developed unique and distinctive behaviors gives credence to the idea that animals have “cultures,” that both define them and help them survive. Increasingly, conservationists are arguing that understanding and incorporating those cultures into conservation strategies is a key to success. Last month, delegates at the UN Convention on Migratory Species passed a resolution (PDF) that calls on conservationists to acknowledge and incorporate animal cultures into conservation thinking.

This is a key evolution in thinking about the animal world and its future. Philippa Brakes of Whale And Dolphin Conservation explains:

In 1975 sociobiologist E. O. Wilson noted the influence of social structure on fitness, gene flow and spatial patterns in some species. Deeper understanding only started to emerge in the past decade, and wildlife policy has been slow to catch up.

The new resolution recognises both positive and negative consequences of non-human culture. Individuals passing on knowledge may increase population viability by allowing the rapid spread of innovations amid environmental challenges, which could mean more-resilient social groups. On the other hand, the effects of human-induced threats may be amplified by the presence of non-human culture.

How so? The type of threat and the type of society is important. For example, orca societies are often conservative and so may be reluctant to adopt an innovation in response to a new threat, like the depletion of a food source. The distinct cultures of different groups also lead orcas to behave in different ways, and this can make one group more vulnerable than another. So they should be assessed as cultural groups, rather than by absolute population numbers.

In African elephants, older matriarchs are thought to act as “repositories of social knowledge”, holding information important to the survival and fitness of their social group, such as the location of food or water. Their removal may have impacts beyond the loss of one elephant.

There is also evidence that baleen whale calves learn migratory routes from their mothers and that hunting two species – southern right and humpback whales – meant that critical knowledge was lost.

I would add another benefit. Understanding the distinctive cultures of animals opens the door to empathy. A mother elephant or whale who has knowledge and plays the same role that your own mother might is more than just a whale or elephant. She is inherently valuable and her protection is inherently important.

That makes a difference. It shouldn’t, in my view. But unfortunately humans care more when they can see parallels to their own lives and social structures. So the more awed and compelled we are by any cultural behavior, like bubble-feeding, the better.

Humpback Learnin’

Just one more data point in my broader theory that the more we study animals in general, and cetaceans in specific, the smarter we realize they are.

From NatGeo:

Whether it’s learning a new song, figuring out how to use tools to forage for food, or picking up the local customs, learning from others is an important part of life for many animals, including people.

The idea of a culture or traditions—behavior shared by an identifiable group and acquired through social learning—in cetaceans, a group including whales and dolphins, has been controversial.

But a new study finds strong evidence that a group of humpback whales (Megaptera novaeangliae) in the Gulf of Maine (map) is sharing a newly observed feeding behavior via their social networks. (See related blog: “Sharks Have Social Networks, Learn From Friends.”)

That behavior, called lobtail feeding, was first recorded in one whale in the Gulf of Maine in 1980. Since then, 278 humpback whales—out of about 700 observed individuals that frequent the Stellwagen Bank (map) area—have employed the strategy, according to the study, published this week in the journal Science.

What’s surprising to me is not that humpbacks learn from each other. What’s surprising is that we continue to be surprised at all the complex thinking and learning non-human animals do. It’s a reflection of how strong our bias in favor of human exceptionalism is.

One interesting point is that lobtail feeding appears to be a form of adaptation to changes in prey availability:

Lobtail feeding is a variation on a technique called bubble-net feeding, which is used by humpbacks around the world.

In bubble-net feeding, a whale blows bubbles into a kind of net surrounding the prey, corralling them into dense schools. Then the whale lunges up through the school with its jaws wide open, scooping up mouthfuls of food. (Watch a video that shows humpbacks bubble-net feeding.)

In lobtail feeding, the humpback slaps the surface of the water one to four times with the underside of its tail before diving down and blowing the bubble net. Rendell speculates the slaps may keep its sand lance prey from jumping out of the water, away from the whale.

“The origin of this behavior was strongly associated with the collapse of herring stocks and a boom in sand lance stock,” said Rendell. So he and his team suggest that lobtail feeding came about when humpbacks switched from hunting herring to catching sand lances, a type of fish.

So it’s a good thing that humpbacks are smart enough to adapt their hunting strategies and learn from one another. Because humans will continue to impact the oceans and prey they depend on.

This humpback is no doubt glad we are so impressed, but probably wishes he would be left alone to dine in peace:

%d bloggers like this: