Owls are amazing birds. Along with a good vision at night and 360-degree vision, did you know that they have the ability to fly without making any noise which makes them best birds of prey in the dark? Let’s dig deeper.

Silent Flight of Owl Explained

Silent Flight of Owl
Photo by Adam King on Unsplash

Bird’s flight have inspired a lot of techniques of flight, it had played a vital role in the development of air crafts. Owls flight we can learn some more, beyond flight. Owls are nocturnal birds, they hunt in the dark. We know the night atmosphere, it is quiet. Hunting at night is a strenuous task, a small sound can easily warn the prey and make attempts to catch one vain. But, owls have evolved to prey at night. So, they have adapted some morphological features that make their ability to prey in the dark unparalleled.

Noise During Birds Flight

Birds usually make noise when they take flight. This noise is produced due to the vibration of the air due to their wings. These noise depend upon the way wing is flapped, so there can be a variety of sounds corresponding to a single bird. These noises are used by birds to communicate during mating season or other times, sometimes to warn others for upcoming dangers and even to thwart the predators.

But, with an owl, it’s all different. You can find a video of its flight here. This video puzzled me for a bit too. Unlike other birds, it produces no sound at all. It is completely stealthy, undetectable to its prey as it produces no sound at all.

How Owls Can Have Silent Flight But Other Birds Don’t?

Owls have the property of silent flight because of their morphology and aerodynamic property of their wings. Nature have bestowed them such properties so that they could survive in the dark. The morphology of their wings can cancel noise so that the sound of flight is minimized so much that we won’t hear at all.

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For a barn owl, the wingspan is 107 cm to 110 cm and it weighs about 430 grams to 620 grams. Since this weight is low compared to other birds with similar wingspan, it has less wing loading and aspect ratio. This makes them able to fly slowly and non-violently, resulting in mild vibration and low sound. This is one of the causes of noise reduction during owl’s flight.

Furthermore, owl’s wings have serrations on their edges which can split the flow of air so that the aerodynamics can be manipulated and can have a steady flight. The fringes in inner feather vanes also take part in trailing edge noise reduction by gliding into the grooves of the lower wing surface. Finally, any remnant sound is absorbed by the velvet-like surface on its body to reduce noise even more.

So, the morphological features of owl make them able to have silent flight and also inspires us to build better machines and air crafts by showing methods to cancel noise in them.


Author

Ashwin Khadka is a Physics graduate from Tribhuvan University, Kathmandu, Nepal. He is a science enthusiast, researcher and writer. Apart from writing he is also a researcher, with specialization on thin films for electrodes in solar cells.

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