Mar. 7, 2013 — When different species of birds flock together, their flight formations are determined by social dynamics both between and within species.

New research from the Universities of Cambridge and Exeter reveals for the first time that, contrary to current models used to explain the movement of flocks, the differences between bird species and social relationships between individuals play a critical role in determining the dynamics of mixed-species flocks.

The unified behaviour of bird flocks has puzzled scientists for hundreds of years. One naturalist from the turn of the century even suggested telepathy may be involved. There have since been more logical explanations, including mathematical models that show that repeated interactions among individuals following simple rules can generate coordinated group movements. However, these models usually rely on the assumption that individuals within groups are identical and interact independently, which may not reflect reality.

Jolle Jolles, a PhD student at the University of Cambridge's Department of Zoology and author of the paper, said: "Spectacular collective behaviour can be found in a large range of animal species, and we now know that often these complex coordinated group movements may be the result of individuals following simple rules. However, rarely are the individual characteristics and social relationships within them taken into account. Our research highlights that these striking displays of group behaviour are much more complex."