Migratory birds have to cover several thousand miles on their hunt for food and warm climates. Many species, particularly passerines and other smaller birds, make their journey in large flocks, probably because there is safety and warmth in numbers.
Other birds fly in formations of V and J shapes, sometimes inverted.
It is a wonder to behold if you catch an autumnal glimpse of one of these echelon formations overhead.
If you’re aware of season migration patterns, it is easier to identify which birds fly in a V formation, should you spot one.
Large-winged birds such as geese, swans, and waders are most likely to fly in a V formation. Their powerful wingtips can create strong currents for any following birds to utilise; thus, saving them energy.
Birds that fly in a V formation
The Canada goose is a British inhabitant; the bird you’re most likely to see flying in formation.
Studies show that that, on any given journey, a goose can cover 70% greater distances than when flying alone. The conserved energy, pinched from the bird in front, keeps the goose airborne for much longer.
All swans can fly; most migrate to warmer climates as they cannot survive harsh winters.
They fly in V formations with the lead bird proudly sticking his long white neck out in the direction of their destination.
Often, if their offspring haven’t found a mate, they will join the formation with their parents.
Ducks cannot withstand cold temperatures and migrate annually, looking for a reliable food source and warmth.
They comfortably travel thousands of miles, flying in a V formation and rotating the lead flyer to conserve the whole group’s energy levels.
Pelicans migrate in small groups and choose to fly in a V formation. Studies show that each bird has a favourite position in the V, either on the left, right, or back.
Whichever their favoured spot, each bird still takes its turn at the head of the group.
It’s hard to imagine flamingos flying at all, let alone in formation, but they do. They tuck their long legs away before setting off on long journeys, preferring to fly higher where the thermals help to keep them afloat.
They need to flap their wings rapidly, so it becomes tiresome very quickly; therefore, the flamingo likes to fly in formation to conserve energy.
They either fly in a V-shape or a wobbly line.
Cranes are another wading bird that flies in a V formation. They gather in large numbers near wetlands before taking off, often with an adult at the helm and juvenile birds in the rear.
Their flight is quiet and elegant, a wonderful sight for those lucky enough.
Why birds fly in a V formation
Much like a squadron of aeroplanes or a battalion an armada of ships, birds choose the V formation to ensure that every single member has a clear line of sight directly ahead.
However, this isn’t the main reason for adopting this flight method, favoured due to its energy and stress-saving abilities.
Birds that fly individually expend between 11 and 20% more energy than those in a formation; a huge difference when they cover thousands of miles, often across open seas.
How birds fly in a V formation
When a bird flaps, it creates a rotational vortex that rolls off each wing. The air immediately behind the bird forms a ‘downwash’ – the air naturally pushes downwards.
The air that rolls off the wingtip behind the bird, but out to the side, creates an ‘upwash’ -the air pushes upwards.
Any bird flying in this zone floats on the upwash, staying in sequence by matching the wingbeats of the bird ahead.
It is unsure how the leading bird is chosen, whether there is a hierarchy system. The group ensure the head bird doesn’t tire by interchanging at regular intervals.
If a bird flies directly behind another during these changes, they get caught in the downwash. Cleverly, they instantly reverse their flapping motion to the opposite of the bird ahead to ensure they don’t plummet.
How do we know this…?
IN 2001, a scientist called Henri Weimerskirch fitted a flock of pelicans with heart monitors, extracting their data after the flight in a formation.
He found that the birds at the back had significantly lower heart rates compared to the lead bird as they had had to flap their wings less.
To take the experiment one stage further a group of scientists attempted to discover if flying in formation was something a parent taught its young.
They took 14 hand-reared ibises to show them their generational migrational route from Austria to Italy.
They used a micro-light to lead the flock; amazingly, the birds automatically flew in formation. Each bird flew around a metre behind and to the side of the one in front. They also observed the birds’ reversed flapping motion to reduce the effects of downwash from the one ahead.
These large birds with wide wingspans have intuitively devised a time-efficient and stress-free method of navigating long distances.
Instead of having to be aware of every other member of the group, flying in a V formation frees up each bird to simply remain alert to the bird ahead.
It is an impressive system, the birds can fly further for longer, and with every member having a good view, they avoid most imminent predator attacks.