The synchronicity of a flock of birds in flight is something that has mesmerized humans for as long as we have been watching them.
The way they fly in V-formation, or in perfect unison as vast clouds of thousands of individuals is a natural phenomenon.
To achieve this level of coordination, do flocks of birds have a social hierarchy, with a leader who decides when to turn, and in which direction or where to fly next?
The leader bird in the flock changes throughout the flight. Coordinated flight in birds is achieved by every individual both leading and following, by anticipating sudden changes in the direction or speed of the flock by looking at the birds closest to them.
All bird species have different social structures and dynamics. For example, in flocks of pigeons there is a social hierarchy and leader-follower dynamics.
When flocks of geese, pelicans, or ibis migrate, flying in lines or in V-formation, they take turns flying as the leader at the front.
In giant flocks of starlings, there are more complex leader-follower dynamics at play, allowing thousands of individuals to move as one.
Social Hierarchy in Birds
Flocks of pigeons do not fly in elegant formations, but they do have leaders amongst them. Their social order is determined by who flies the fastest and has the best navigation skills.
The leader flies in the front of the flock to steer them to their destination.
Pigeon social hierarchy is dynamic, with other birds taking over the leadership role regularly.
This contrasts with turkeys and chickens, that also have a social hierarchy, or pecking order, but this is more permanent.
Individuals that are more dominant by nature rise to the top of the pecking order by challenging other birds.
The leaders, those at the top of the pecking order, will eat or drink before others, take up the most comfortable roost positions and use the most favorable nest boxes to lay their eggs.
Geese demonstrate strong social group behavior, as they raise their young communally. There may be a dominant goose in the flock, but this does not determine who flies in front when they are migrating.
Initially the strongest flyer will take up the lead position and then the geese take turns flying in front. They communicate when it is time to change by honking.
Starlings and blackbirds flock together densely on winter nights to roost, but because there are such a massive number of individuals in the flock, they do not form a social order.
They stay close together to keep themselves, and each other warm.
Why Do Birds Fly in a Flock?
Birds flock together for the same reason that many other species gather in large numbers, like swarms of insects, herds of antelope, or schools of fish. There is safety in numbers.
Birds that fly alone or stray too far from the flock are more likely to be picked off by predators. Each flock member has a strong instinct to stick together, for the sake of self-preservation.
Hawks will attack a flock of starlings, and the flock responds in split-seconds, twisting, splitting, and merging to avoid the attacker. These sudden movements confuse hawks, keeping the starlings safe.
Other than having more pairs of eyes to look out for predators, it is also an advantage for birds to flock in large numbers, because there are more individuals on the lookout for food.
Is There a Leader When Birds Fly in V-Formation?
Many large species of birds fly in a V-formation on their long migratory journeys. Birds are able to travel over 70% longer distances when flying in a formation, versus flying alone because it is more aerodynamic.
A team of zoologists from the UK, Austria, and Germany, researched the annual migration of northern bald ibises from Austria to Italy.
The birds must travel a distance of 1500 kilometers, pushing their bodies to breaking point. Many juveniles do not survive their first journey.
The ibises fly in V-formation as a way to deal with the high energetic cost of migration.
This formation is strategic, as it makes long-distance flights as energetically efficient as possible.
The bird flying at the front of the V exerts the most energy, but every bird behind them is able to benefit from the extra lift that their wings create.
Individuals in the flock take turns flying in the front, to share the load.
Geese, pelicans, and many other migratory birds use the strategy of flying in formation, but they do not have leaders who coordinate their flight.
What is Murmuration?
This fabulous word refers to when birds, like starlings, flock together in thousands, moving across the sky in giant swathes, as a single entity.
They twist, and swoop, and change direction in split seconds, as a way to confuse their predators and warm their bodies prior to roosting overnight.
Exactly how murmuration works has been a mystery for hundreds of years. Ancient Romans’ explanation was that murmuration was the Gods’ way of communicating with humans.
In the 1930’s our best theory was that birds have telepathic abilities.
In more recent years, ornithologists, behavioral biologists, theoretical physicists, and computer scientists have worked together to research exactly how birds are able to put on these fantastic aerobatic displays and why.
Is There a Leader in Murmuration?
In 1984, Wayne Potts published a key paper in the journal Nature that started us on the path of discovering birds’ secret behind murmuration.
Large flocks of starlings, sandpipers, or tree swallows do not have a social hierarchy or leaders, yet they move and change direction in perfect unison.
They do not simply follow the bird in the front of the flock, there are more complex leader-follower dynamics at play.
How Murmuration Works
Group cohesion in a murmuration relies on each flock member obeying three rules:
- Do not collide with a neighboring bird.
- Fly in the same average direction as neighboring birds.
- Fly towards the average position of neighboring birds.
By following these three simple rules, giant flocks can move at high speeds, changing direction quickly in response to attacks.
Birds anticipate abrupt changes in the direction the flock is flying, by observing the six or seven birds closest to them.
When one bird changes direction, the change spreads like a wave through the flock.
Pott’s named his theory the chorus line hypothesis because of the way birds know to change direction or speed, in the same way that dancers in a chorus line know when to kick their leg up – by anticipating the change.
While some flocks of birds may have a social hierarchy, this does not mean that they follow a single leader when they are flying as a flock.
A bird’s ability to move in a cohesive, coordinated way is an evolutionary advantage, in terms of avoiding predators, finding food, and warming their bodies before they roost for the night.