Flocks is a group of birds conducting flocking behavior in flight, or while foraging. The term is akin to the herd among mammals.
The benefits of aggregating in flocks are varied and flocks will form explicitly for specific purposes.
Flocking also has costs, particularly to socially subordinate birds, which are bullied by more dominant birds; birds may also sacrifice feeding efficiency in a flock in order to gain other benefits.
The principal benefits are safety in numbers and increased foraging efficiency. Defense against predators is particularly important in closed habitats like forests where depredation is often by ambush and early warning provided by multiple eyes is important, this has led to the development of many mixed-species feeding flocks.
These multi-species flocks are usually composed of small numbers of many species, increasing the benefits of numbers but also increasing potential competition for resources.
Computer simulations and mathematical models which have been developed to emulate the flocking behaviors of birds can generally be applied also to the “flocking” behavior of other species. As a result, the term “flocking” is sometimes applied, in computer science, to species other than birds.
This article is about the modelling of flocking behavior. From the perspective of the mathematical modeler, “flocking” is the collective motion of a large number of self-propelled entities and is a collective animal behavior exhibited by many living beings such as birds, fish, bacteria, and insects. It is considered an emergent behavior arising from simple rules that are followed by individuals and does not involve any central coordination.
Basic models of flocking behavior are controlled by three simple rules:
- Separation — avoid crowding neighbors (short range repulsion)
- Alignment — steer towards average heading of neighbors
- Cohesion — steer towards average position of neighbors (long range attraction)
With these three simple rules, the flock moves in an extremely realistic way, creating complex motion and interaction that would be extremely hard to create otherwise.