Why birds of a feather make patterns together
PUBLISHED: 08:18 03 February 2018
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In The Countryside: Rex Hancy on how birds' flight patterns are far from random.
Dry air and a low-angled sun can produce a clear light which intensifies natural colour. Our silver birch, beautiful in all seasons, looks almost magical in autumn when the light streams from a low westerly sun. Recently I was fortunate enough to catch a glimpse of a group of intensely white birds flying in formation, keeping perfect station with each other. The sky itself was a clear all-over grey-blue. Even at a distance, the brilliance of the light highlighted the small flock so my tired eye was able to recognise the birds for what they were.
There were four gulls, zooming, diving, soaring and twisting in the air, giving a display as exciting as one by the Red Arrows. I wish I could say my admiration was unbounded but I soon realised their balletic synchronised movements were motivated entirely by aggression and greed. The leading bird had picked up a tasty morsel thrown down by a well-wisher. Instead of looking for equivalents for themselves, the other three were in fact mobbing the lucky one, hoping he would be forced to discard his prize. The flying display was the result of all three keeping as close as possible while following his efforts to escape. I was left with a classic case of “What happened next?” because the group was quickly out of sight.
Watching birds in flight is a special pleasure. A swan, so graceful in the air and equally so when on the water, has a moment of awkwardness when it has to slow dramatically when it effects the transition. Too much speed and momentum would be dangerous so the brakes have to be applied. Does it shrug off a hint of embarrassment? Of course not, but human eyes could read it as such.
A group in flight take up station and the sound of their massive wings can be heard from quite a distance. Large birds employing the flap and glide method of flight know instinctively and then by practice that they can utilise air fluctuations created by the leading bird. There is a perfect position behind each wing of the leading bird and of course each one creates the same facility for any follower. The familiar V formation we associate with migrating geese is the result.