V-formation flightДЇor centuries, people have been fascinated by V-formation flight. These two flock types are thought to provide different benefits and disadvantages. When birds flock in the air they form either clusters or V-formations. Many studies have demonstrated that individuals who are less well aligned to the group, slower to respond or choose the wrong direction are more likely to be preyed upon. Likewise, for all animals travelling in groups collisions or indecisiveness may lead to individuals being more easily picked out by predators. Therefore, for birds in a flock, decisions need to be made literally on the wing, and at a certain speed. While this speed will vary greatly depending on the size of the bird, all birds will eventually stall below a certain minimum speed. Birds can only fly so slow before they are no longer creating enough lift to keep themselves airborne. However, such signals pertaining to group movement and direction cannot be as subtle or slow for animal groupings moving in air, due to the risk of collision between flock members, or falling out of the sky. For example, herds of ungulates seemingly make group movement decisions through facing the same direction, or through slow directional movements aimed to illicit a response from other herd members. Bird flocks are a particularly exciting study system due to their dynamic nature, the speed at which events and decision making need to occur, and the potential for collisions and injury. How birds assemble and the dynamics within the group have significant implications for individual energy expenditure within the flock. However, one has to be careful when using group size measures to characterize animal sociality, because average individuals live in groups larger than mean group size.Flapping flight is the most energetically demanding mode of locomotion in vertebrates. Group size is a major aspect of the social environment of gregarious animals. 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. Defense against predators is particularly important in closed habitats such as forests where predation 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. The principal benefits are safety in numbers and increased foraging efficiency.

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 benefits of aggregating in flocks are varied and flocks will form explicitly for specific purposes. The term is akin to the herd amongst mammals. File:Flock of birds at Rome.oggДЄ flock is a group of birds conducting flocking behavior in flight, or while foraging. Red-billed Queleas form enormous flocks-sometimes tens of thousands strong. File:Red-billed quelea flocking at waterhole.jpg

Flocks of birds