Owls And Their Feathers
Owls And Their Feathers
Have you ever wondered how an owl can fly absolutely silently and in complete darkness? It has evolved superbly to do just this, and in so doing, it is taking advantage of the midnight hours when we humans are out of the picture, fast asleep.
I don’t know if any of you are watching ‘Mammals’ on BBC1 at 7 pm but I am. It is another wonderful nature programme narrated by David Attenborough and well worth watching. This opening episode, ‘Dark’ was all about mammals at night. 80% of mammals are active at night and more than two thirds are solely nocturnal. Bats are the most successful of nocturnal mammals, making up a staggering 20% of all mammal species.
So how does an owl manage to pin point its prey in complete darkness? And catch it? Firstly it has very sensitive hearing and can hear the rustle of a mouse under the canopy of grass from ….Secondly, it can target its prey by hovering over the sound with its specially adapted wings. And thirdly it has very long legs, that it shoots forward as it drops onto its prey. Only one in ten of these attempts results in a kill, the rest use up a huge amount of valuable energy and that is why it is vital that the owl can hunt most nights. As there are many things that can prevent this, such as too much artificial light which interfers with its senstive night vision, too much noise preventing it from hearing and rain – too much rain.
The owl has evolved to fly almost silently, and it does this by evolving especially large wings in relation to its body size, which allows it to fly unsually slowly – as slowly as two miles per hour, as in the case of the Barn Owl, by gliding noiselessly with little flapping. In addition the structure of their feathers serves as a silencer, the comb-like serrations on the leading edge of the wing feathers break up the turbulent air enabling the Owl to fly silently. The smaller streams of airflow are further dampened by a velvety texture, unique to Owl feathers, and by a soft fringe on the wings trailing edge, these adaptations together streamline the airflow and absorb the sound produced. I wish I could put this into place for aeroplanes and garden machinery!
Due to the feathery nature of these vital ‘silencers’ the wings are delicate and do not take much preening with oil, unlike a Duck. Owls prefer not to fly in heavy rain and wet weather conditions, in order to maintain the fluffiness of their silent flight, so it has been a tough Winter for them this year!
Athene English