Barn owl wings adapted for silent flight

Barn owl (c) Kim Taylor / naturepl.com The curvature of barn owls' wings helps them fly slowly and silently

Related Stories

Their screech is one of nature's eeriest sounds, but barn owls hunt in almost total silence.

Now researchers in Germany have revealed how the predators' wings are specially adapted to allow noiseless flight.

Their supreme stealth is thanks, largely, to their ability to fly so slowly - with relatively little beating of their wings.

And the shape and size of the owls' wings enables this very slow flight.

Dr Thomas Bachmann from the Technical University Darmstadt in Germany recently presented his study of barn owl wings at the Society for Integrative and Comparitive Biology's annual meeting in Charleston, South Carolina.

Barn owl (c) Lynn M Stone/NPL
  • Barn owls can locate their prey in total darkness, using only their hearing
  • The owls' heart-shaped face works in a similar way to humans' outer ears - collecting and directing sound toward the inner ears
  • Each of a barn owls' two ears is a slightly different size and shape, and one is higher on the bird's head than the other. The owls can analyse the differences in the sound received by each ear to automatically calculate the exact position of that sound-source

He explained to BBC Nature that barn owls were highly specialised nocturnal hunters.

"They hunt mainly in the dark, so visual information is very limited.

"They use acoustic information to locate their prey."

Their silent flight helps them listen for the scurrying of the voles they hunt for, and also reduces their chances of being heard by the prey as they approach.

To find out how they managed to fly so slowly and quietly, Dr Bachmann examined the birds' wings in minute detail.

He examined the plumage and took 3-D medical scans of their skeletal structure.

The wings' most important features, he explained, were the high curvature or "camber" of the wings. This curvature means that each wing beat produces more lift.

This is because, Dr Bachmann explained, the air flow is accelerated over the upper surface the curved wing. "So the pressure drops," he said. "[And] the wing is sucked upwards into the lower pressure on the upper wing surface."

Micrograph of barn owl wing (c) Thomas Bachmann The fine feathery fringes of each wing also help silence the owl's flight

The feathery edges of each wing are also extremely fine - reducing any loud turbulence during flight, explained Dr Bachmann.

"Friction noise between single feathers is also reduced [by] their velvety surface," he told BBC Nature.

In fact, Dr Bachmann explained, "all the body parts of the owl are covered by very dense plumage - owls have more feathers than other similarly sized birds".

This soft, dense plumage absorbs other sounds the birds make as they fly.

Dr Bachmann and his team say their eventual aim is to use the structure of barn owl wings to inform the design of new, much quieter airfoils for the aviation industry.

"We're trying to understand the basic principles... that influence the airflow over aircraft and thus reduce noise," he explained.

"[But] we are far away from that point. Maybe in 20 years we can present such a wing.

"Until then, we will conduct many more experiments on owl wings."

Barn owl wing (c) Thomas Bachmann The structure of barn owls' wings could provide a guide for the design of quieter and more efficient airfoils

More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas


  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers


  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment


  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists


  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today


  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?


  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?


There have been 75 solar eclipses and 167 major volcanic eruptions in my lifetime

Nicole Malliotakis on Twitter comments on the events that have happened since she was born by using our personalised Your Life on Earth interactive infographic.

Things To Do

RUN BY THE BBC AND PARTNERS

More Nature Activities >

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.