Migrating birds fly in a V-formation when traveling great distances. Nearly all birds do this to benefit off of the principles of aerodynamics. Strangely, birds take turns flying at the front even though there is no obvious advantage to the individual bird. Though, a new study released explains why migrating birds do this. They also explain why cooperation is an influential evolutionary notion.
In 2014, scientists at the United Kingdom’s Veterinary College released a new study showing and deducing why the V-formation is so important. The echelon formation, better known as the V-formation, shows clear signs of energy savings to the individuals behind the lead bird in the flock. This effect is called aerodynamic wash-up. Aerodynamic wash-up occurs when migrating birds take advantage of the updrafts created by the flapping wings of the preceding bird. This new study showed that flying in the V-formation is exactly as much about the birds flapping at the right time as it is about flying in the right place.
Even though, this explanation covered the basics about the notion of the formation, the Veterinary College did not explain why the birds voluntarily choose to lead the front in flight when there is absolutely no aerodynamic advantage. For the leading bird this is a major, strenuous job. Long-distance migrations are tiring to the birds. This results in higher mortality rates for the birds than any other time during the calendar year – especially for younger birds. For example, greater snow geese have a mortality rate is 5% for adult birds and 35% for young birds during the fall migration season. The deaths happen due to the weakened immune system, dehydration, and starvation. Though, it is mainly caused by the immense physical demand of long-distance flight.
Regarding the notion of the lead bird, scientists stated that there is what they call a “selfish gene.” The hypothesis suggests that migrating birds should act selfish and not want to spend a prolonged amount of time flying at the front. However, Bernhard Voekl of the University of Oxford’s Department of Zoology, conducted an astonishing experiment that showed that migrating birds cooperate in this “social dilemma” even though there is a high risk of migration.
To explain why migrating birds do this, researchers at the University of Oxford studied the flight behaviors of a group of 14 young birds – the Northern Bald Ibis. They conducted this during a human-guided fall migration. A highly sophisticated GPS device was attached to each bird so the researchers could track their flight routes and their behavior during sustained flights.
As the researchers carefully observed the flock, their investigation came to realization that the length of time one bird is leading the V-formation has a powerful correlation with the time it can itself can take advantage of when it is flying behind another bird. Unbelievably, the birds work in pairs. They match the time spent in their partner’s wake. They frequently takes turns leading the flock. The researchers measured that each individual spent an average of 32% of time behind their partner bird and nearly the same amount leading the V-formation.
The question remains, why do birds do this? Researchers stated that cooperative flight patterns among migrating birds increases the chance of success regarding direct reciprocation. Through the notion of game theory, they explained non-cooperators earn less of an advantage than when cooperating birds are engaged in flight.
They also argued that multiple sessions of this type of flight encourages the symbiotic relationship. The more they do this the more mutual gains of cooperation can happen. Moreover, altruistic acts are more likely to benefit than what is lost by the donor – making both birds stronger partners in the long run.
If migrating birds work together, the flock has a greater chance of having all of its feathered brethren make the long trip to their destination. By using aerodynamic wash-up, the migrating birds at the front of the V-formation will benefit from the cooperation of others.
By: Alex Lemieux
Picture: Chuckcars – Flickr License