Study of starling formations points way for swarming robots

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Study of starling formations points way for swarming robots
By Roger Highfield, Science Editor
Last Updated: 8:01pm GMT 29/01/2008




Scientists have uncovered a simple rule that explains how thousands of starlings flock in formation and hope to use the discovery in the future to coordinate swarms of robots.

Video: Starlings in flight
How the humming bird got its chirp
The reasons why the starlings are able to fly with Red Arrow precision in vast numbers, tumbling and banking in nervous unison and without colliding, has tantalised scientists.


The reason why starlings are able to fly in precise formations has tanatalised scientists for years
Now it turns out that the secret is for each bird to track seven others, says the first detailed direct observations to have been reported by STARFLAG - Starlings in Flight - a European project involving biologists, physicists, and economists.

The scientists wanted to find out how flocks remain so incredibly cohesive - never leaving a bird isolated - when under attack by a bird of prey.

The team used new methods to gather data on large flocks of starlings over the skies of Rome’s Termini railway station to test the various theories and found that the behaviour of flocking birds is very different from what was believed up to now.

Current computer models assume that each bird interacts with all birds within a certain distance. But the new observations, however, show that each bird keeps under control a fixed number of neighbours - seven other starlings - irrespective of their distance, which is the secret of how they stick together.

“This is very robust and works wherever your neighbours are,” says Andrea Cavagna of Italy’s National Institute for the Physics of Matter.

A flock under predator attack may expand dramatically, but birds can regroup very quickly because the cohesion does not depend on the physical distance among starlings, but rather on their ability to interact with a fixed number of neighbours.

“We finally cracked the experimental problem, and we have now data on the individual 3D position of starlings within large flocks (around 3000 birds) in the field. We are the first to have produced this kind of data, and we are now in the position to compare with existing models and theories,” he adds. “Our result show that one of the main assumptions of current models and theories is, in fact, quite wrong.

advertisement“Up to now numerical models of flocking had never been tested against empirical data, and it was impossible to select the right model. Now, thanks to our data, we can really measure what goes on within a flock,” says Cavagna.

The results, published in the Proceedings of the National Academy of Sciences, may be important for fields such as mobile robotics, where highly coordinated swarms of simple units such as robots must solve complex problems such as sweeping an area for surveillance, using simple rules.

The team also concludes that the birds are smarter than was thought. “An interaction based upon the number of neighbours, rather than their distance, implies rather complex cognitive capabilities in birds,” adds Irene Giardina, a fellow researcher, of the Centre for Statistical Mechanics and Complexity in Rome.



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