Many species of birds perform graceful synchronized movements. But how do they manage to coordinate themselves so well when they flock? The answer is a bit more complex than just 'follow the leader'.
Researchers at Southeast University and China University of Mining and Technology studied three flocks of 10 pigeons each. For each individual, the position, velocity, and acceleration were tracked so that the researchers could construct a causal network. This kind of data allowed the researchers to assess how each individual impacted the group's dynamics and observe flocking rules.
"Understanding the underlying coordination mechanism of these appealing phenomena helps us gain more cognition of the world where we live," said author Duxin Chen, an assistant professor at Southeast University in China.
Previous research suggested that flocking follows three basic rules: avoid collision with your neighbors, match the speed and direction of motion with the rest of the group, stay near the center.
The new findings show that's not nearly all there is to it. The researchers found some other trends and insights into flocking, such as the fact that every pigeon has neighbors it influences, as well as neighbors it is influenced by. What's more, who gets to influence who constantly changes during flight.
"Interestingly, the individuals closer to the mass center and the average velocity direction are more influential to others, which means location and flight direction are two factors that matter in their interactions," Chen said.
The researchers also observed that flight competition was relatively intense throughout the flocking behavior, suggesting that there may be important social considerations such as hierarchies.
Birds flock because it offers them protection. Individual birds that are separated from their flock are more likely to be picked off by predators. It also serves other purposes. For instance, when one bird finds food, others in the flock get to eat, too.
One interesting thing about flocking behavior is that birds move in unison in a maneuver wave. Since 1984, zoologist Wayne Potts showed that birds can anticipate sudden changes in the flock's direction of motion. His research showed that birds flock in unison three times faster than their potential reaction time if they were simply reacting to their immediate neighbors. Once a change in direction is triggered, it spreads through the flock like a wave.
This kind of work can be used to model and study other types of coordinated behaviors, such as that of immune cells, insect swarms, and bacterial colonies, which is something that the authors plan on studying in the future.
The findings appeared in the journal Chaos.