Flocks of birds flying through the autumn sky are a common phenomenon that can be observed every year. Some species, mainly small birds that feed on insects, leave their hatched nests in separate or shapeless schools. But larger species - wild geese, swans, cranes, act differently. Rising into the sky, they form a wedge, adhering to this form of construction throughout the flight. But why do they fly this way?
It turns out that this form of building a pack is not at all random. In nature, there are few accidents in general, and as for bird flocks, this form is unusually effective in practice.
Air flow in flight
For small birds, any special flock construction is really ineffective, and large individuals significantly benefit by flying over a wedge. Such a construction provides optimization of air flows, thereby minimizing the energy costs of individual birds. Of course, that cranes do not make preliminary calculations of aerodynamics - they just fly like that because they feel that flying is physically easier for them. This has been proven by instruments that the researchers attached to ibises flying south.
Interesting fact: when a bird flies a little behind and a little to the side of another bird, it catches upward swirling currents from it, which makes flying easier.If a bird flies strictly from behind, on the contrary, it must exert additional efforts to extinguish these vortex flows, which in this case already impede normal flight.
In order to make the flight the easiest for each large individual, generating tangible ascending and descending flows during flight, birds in the wedge synchronize the movements of the wings as well. It is possible that many of the nuances of a flock flight are laid at the instinct level, but many birds simply learn during the flight, feeling in which case the movement is easier, and in which it is more difficult. Large birds are smart, well-trained creatures, it is not at all surprising that they quickly learn to improve their innate skills.
Following the leader
In addition, the birds in the flock instinctively follow the leader, which each individual must constantly see during the flight. Building with a wedge allows you to see the leader and all his maneuvers, to adapt in time to changes in the leader’s course. It is so convenient that modern military pilots piloting fighter aircraft also prefer to stick with a wedge.
Energy saving
Continuing to consider the features of fighter piloting, it is necessary to indicate another important point. Pilots are well aware that flying with a wedge saves fuel, in which case each aircraft consumes fuel more slowly in its tanks. Birds can also save energy by moving around in this well-constructed structure.The aerodynamic flows from the front of flying comrades maintain the stability of their flight, and this is important when you consider that flights can occur over many thousands of kilometers.
The greatest load in flight falls on the front of the flying bird, the leader. It sets the rhythm and cuts through the air space, transmitting flows further to flying individuals. A leader is the strongest, healthiest bird that can easily withstand such loads. When the leader gets tired, another bird from the leader group may temporarily take its place in front of the wedge. This is also effective - when the maximum loads are on strong, hardy individuals, yesterday's chicks and weaker birds can fly, using streams, spending a minimum of energy. Thus, the whole flock can reach the target, and losses during the flight will be minimal. This is important for keeping livestock.
Why aren't all birds flying in a wedge?
As practice has shown, building a wedge is relevant only for large birds, it turns out to be effective only if the individuals have sufficient mass. Small birds collide with other aerodynamic phenomena during the flight, this is due to their small mass. A wedge is completely useless for them, so they fly apart or use other ways to build a flock.
Thus, large migratory birds use the construction in the form of a wedge, since it turns out to be the most effective for them. In this case, they immediately receive a number of advantages: they constantly see the leader, they can use streams from stronger birds flying in front.This construction option can be considered laid down at the genetic level, however, some things flock birds have to learn during the flight - for example, to effectively use the flows and energy from the individuals in front of them.
