Collective action in birds.

Observing the behaviour of others is a cheap and effective way of acquiring up-to-date information about the environment. Further, an animal that changes its behaviour in response to acquiring social information effectively propagates that information forwards. Although the rules that govern how individual birds detect and respond to social cues are often very simple, they are able to produce a diverse range of collective actions from which individuals can reap benefits that include predator avoidance and more accurate estimations of the environment. Understanding how and why individual-level rules that favour the emergence of collective behaviour have evolved therefore requires knowledge of the ecological and social contexts in which they are expressed. The breadth of research on social behaviours in birds is an unparalleled window into the ecology of collective behaviour and provides many opportunities to test whether different species overcome different ecological challenges using similar social rules and whether the collective behaviours of birds can act as sensors for the environment.