When in this flight pattern, the birds are constantly changing position. The lead bird, eventually, drops to the back when tired and another assumes its place at the front of the V formation. In addition, this setup allows the birds to retain visual contact with each other, ensuring members of the flock are traveling in the correct direction.
The new study gathered information form Portugal and an endangered species of bird – the northern bald ibis (Geronticus eremita), also known as the Waldrapp. The birds are raised in captivity to increase their success and then reintroduced and taught to follow their natural migration route.
When adopting the V formation, trailing birds would fly along the wingtip path of the bird in front to catch their upwash, thereby easing their flight to reduce energy output. However, when positioned directly behind another northern bald ibis, they do entirely the opposite; under these circumstances, the bird will flap “off beat” to the bird ahead – an action that helps to circumvent the detrimental influence of downwash.
Previously, this form of flight wasn’t considered possible, since it requires – according to the research team – “… complex flight dynamics and sensory feedback.” Precisely how the birds achieve this feat is yet to be definitively confirmed. However, it has been suggested that the ibises employ a combination of highly sensitive wingtip receptors (filoplumes), reflex reaction circuits in the brain and vision to coordinate their movements.
The research could even have implications for the aviation industry. Airlines are dedicating time and money to determine how birds use updraft to their advantage, in the hope that they can use this knowledge.