Watching the starlings swoop and draw shapes in the sky is a true spectacle in the freezing, dark winter nights. Throughout the world, these birds demonstrate their agility in flocks, carrying out choreographies executed in perfect synchrony. We can not avoid asking ourselves how they do so as not to clash with each other and, above all, why they make such an air show.
Almost a century ago, in the 1930s, a leading scientist said that birds should have Psychic powers to be able to fly in flocks. Fortunately, modern science is in a position to offer explanations more adjusted to reality.
To understand what starlings do, we must go back to 1987, when the theoretical computer scientist Craig Reynolds developed a bird flock simulator. The boidsThe name that Reynolds gave to the creatures followed three simple rules to create their movement patterns: the closest birds would move away, align their direction and equalize their speed, and the farthest ones would approach.
Some of these patterns were used to create groups of animals in movies. For example in Batman Returns (call Batman returns in Spain), the flocks of bats and the "army" of penguins They were designed thanks to technology. This model did not require long-range guidance or supernatural powers, but rather local interactions. The Reynolds program showed that it was possible to recreate the flight of the flocks if the simulation followed simple rules, approaching almost exactly the groups of birds that can be observed in the wild.
From there, a world of possibilities was opened in the simulation of animal movements. In 2008, a group of Italian scientists recorded the flight of a flock of starlings near the train station in Rome, then reconstruct their positions in 3D and show the rules that the birds followed. The researchers found out that the starlings sought to imitate the direction and speed of the seven birds closest to them, and not of all those near as they thought.
When we observe a flock that moves in the form of waves or draw beautiful and diverse figures, we can come to think that the birds decelerate and come together, or that they print a greater speed to their flight and separate. Nothing is further from reality; the Models Scientists say that starlings fly at the same pace during these air shows. This perception occurs when we see the flock, in three dimensions, through our two-dimensional vision of the world.
Thanks to the work done for decades by theoretical computer scientists, theoretical physicists and ethologists, we can understand how flocks are created. But going further, we want to know why they are formed and, above all, why this behavior developed in starlings.
The heat of the flock
A simple explanation is the birds' need to warm up during the winter. The birds gather in warm places to stay alive. Starlings can huddle in places as varied as cane fields, dense hedges or scaffolds, in volumes of more than 500 birds per cubic meter, sometimes forming huge groups of several million copies. Such a high concentration of birds would be tempting for their predators, so flying en masse by drawing eddies in the air creates a confusion that prevents any starlings from being hunted.
However, starlings often move to tens of kilometers, consuming in these trips the energy they could save if they rested in warm and nearby places. Therefore, seeing the colossal effort they make, their motivation does not seem to be to enjoy a pleasant temperature.
The formation of the flocks could be due to the security they provide each other when flying together, and from there comes another equally curious idea: perhaps the birds are grouped together to share information about where there is food.
Is "Information center hypothesis" explains that when sustenance is difficult to find, the best long-term solution is the sharing of information among all individuals. In the same way that bees share the location of flowers, birds that find food one day and transmit it to their peers will benefit in future occasions. This conjecture shows some gaps, since the starlings remain by the thousands in the shelters when food is scarce, so this hypothesis can not be proven.
The formation of the flocks could be due to the security that they provide each other when flying together, and from there comes another equally curious idea: perhaps the birds are grouped together so that they can share information about where there is food
In recent decades, our knowledge about group movements of animals has increased considerably. The next challenge we face is to understand the evolutionary and adaptive pressures that have caused the behavior of starlings, and the role they could play in the conservation of the species as these pressures change.
In addition, perhaps we can take advantage of our knowledge to improve the autonomous control of robotic systems. Even who knows if in the future the automatic cars will imitate during the rush hours the behavior of the flocks of birds.