How different bird species forage together in the Antarctic

It's a scene fit for a nature documentary: In the cold ocean surrounding Antarctica, water boils as seabirds dive from above and marine animals such as seals and whales rise from the depths to feast on krill.

But zoom out and this flurry of activity becomes just a tiny speck on a desolate seascape. Scientists were puzzled by how these different species could find the same thing. food source at the same time.

“It’s hard to imagine how forbidding this environment is,” said Sönke Johnsen, a biology professor at Duke University’s Trinity School of Arts and Sciences.

In research published October 6 in the magazine Proceedings of the National Academy of SciencesJohnsen, Duke graduate student Jesse Granger, and UC Davis colleague Gabriel Nevitt describe how several species of Antarctic seabirds forage together and draw conclusions about their conservation and crowd behavior.

Nevitt is a sensory ecologist who has studied how sensory signals cause the formation of feeding aggregations in the Southern Ocean, primarily by petrels and albatrosses (tubular-tailed ones). She describes how, in search of food, some of these seabirds fly closer to the water and track an odorous chemical called dimethyl sulfide (DMS), which is associated with krill. Other species of seabirds fly higher and appear to watch the sniffers, following their lead.

“Using food is probably a very competitive process, but finding it requires cooperation,” Nevitt said.

Tracking the movements of these different bird species in the field is incredibly difficult. During a course in Sweden, Nevitt met fashion designer Granger, who offered to help and invite her mentor Johnsen, an expert in animal vision. The idea was to use computer modeling to better understand how these species interact while foraging.

“You treat each animal like a video game character,” Granger said. “You give him rules about how he should behave, and then you get this unexpected behavior.”

Granger created several flock scenarios with different proportions of bird species that used smell and those that used vision to forage. She also adjusted how species responded to each other—sometimes simply by following what their neighbors were doing; in other cases, observe the birds with the help of additional senses and follow their lead.

By analyzing these different scenarios, the team found that foraging strategies in which different seabird species picked up on each other's signals led to the most successful foraging outcomes. Having even a few birds tracking by scent benefits those who hunt visually to find prey, showing the importance of maintaining balanced populations in the wild to keep them resilient.

“The whole group does better when it's a mixture of different species using different foraging strategies,” Granger said. “If you get past a certain tipping point in size or proportions, the whole group will eventually collapse.”

In addition to informing conservation strategies, this kind of research can help us understand the dynamics of complex systems that involve many people—even crowds of people.

“When we go to the state fair, no one knows where the entrance is,” Johnsen said. Somehow we all make our way to the entrance together. The small percentage of people who pick up certain signals can have a huge impact on the direction of the crowd as a whole.