EU-funded study models the collective landing of bird flocks
A researcher from Hungary has developed a mathematical model that accurately reflects the collective landing of starling flocks. The study was part of the EU-funded STARFLAG project ('Starlings in flight: understanding patterns of animal group movements') under the Sixth Framework Programme (FP6), and is published online in the journal Proceedings of the Royal Society B. Starlings are an invasive species of small songbirds native to Europe, Asia and Africa. Dr István Daruka of Eötvös University in Hungary and the University of Geneva in Switzerland investigated the flight of flocks comprising around 200 starlings. In order to describe the birds' motion and landing numerically, he created a robust theoretical model of the intricate interactions between starlings during collective landing (the few seconds between horizontal flight and touchdown). 'Besides its aerial beauty,' the study reports, 'the flock's well coordinated, almost instantaneous turns, their advanced, collective manoeuvres to avoid predators, their rather extensive, fascinating aerial displays as well as their collective landings raise challenging problems both for fundamental and phenomenological modelling.' Modelling bird movement must take into account the position of the birds, their direction, velocity, density, ordering and flock shape. Attraction at large distances (creating the flock) and repulsion at short distances (avoiding collision) are assumed. Existing models, both two-dimensional and three-dimensional, have addressed specifically the movements of flocks in response to the presence of a predator but have not taken into account aspects of the surrounding landscape. Dr Daruka's model was supported by field observations and successfully accounted for the delicate process of collective landing during foraging flights, taking landscape features into account. His is the first study to present a quantitative model and description of the collective landing of bird flocks. 'These very rich and diverse flocking phenomena,' he concluded, 'present a fruitful and cross-fertilising ground for further physical modelling and biological descriptions.' STARFLAG, funded with approximately EUR 1 million, sought to create three-dimensional mathematical models for animal group movement patterns, focusing on starling flocks. The purpose was to understand the collective movement of flocks in relation to the behaviour of its individuals. Understanding the biological relevance of this relationship can provide insight into group behaviour in humans. Mathematical models developed by the project could be applied to the study of the collective economic choices made by people.