Barn Owl in flight

June 25th 2021

Barn Owl in flight.

Living in the ‘digital era’ has changed how many of us now interact with people, and the world in general. It does make things like this website possible, and we know it reaches people around the world.

There are also numerous ways Assynt Field Club gets to hear of wildlife activity. We get emails, Facebook posts, messages, texts, phone calls and people even tell us in the ‘street’!

Over the past week we have received several short videos that have captured some of Assynt’s wildlife by the right-place-right-time method. So, since we have our own YouTube channel we thought it was time to make a bit more use of it.

Tonight, we will start this mini-series with a video of an adult Barn Owl, Tyto alba hunting near Culkein Stoer. This beautiful bird was filmed at 10.45pm by Carol Langford as it floated across the rough grazing and settled briefly on a fence post.

Silence!

You may have heard that owls don’t make a sound when flying; not quite true but in comparison to most other birds their flight is very much quieter. That’s all down to the unique structure of their wings and the feathers.

Firstly, they have large wings relative to their overall mass. This allows a Barn Owl in flight to manoeuvre at speeds down to two mph. As a result, they can glide almost silently without the need for frequent noise producing flapping.

Secondly, owl feathers are structured in such a way that they act like silencers with three factors contributing to this silencing effect.

The first being a comb-like fringe along the leading edge of the wing. This structure breaks up the turbulent air that normally creates a swooshing noise along the wing’s leading edge.

Next, another unique feature, a velvety like texture to the surface of the feathers helps dampen the noise from the air flowing over the wing. Finally, there is a soft trailing edge to each of those feathers.

The soft fringes on the trailing edge of each wing feather merge tightly in flight with the feather behind. This in effect creates one trailing edge behind the entire wing as opposed to lots of trailing edges behind each feather. Trailing edges are a major source of noise in flight.

So, all these amazing adaptations are a huge advantage when you are hunting small mice and voles scurrying about in the grass. On the one hand, they can’t hear you coming and on the other you don’t make lots of noise which could stop you hearing the mammals in the first place.

These photos are of a Barn Owl that had died of starvation near Clashmore in 2020, and the close up shows the comb-like fringe on the wing’s leading edge. Aren’t they exquisite!

Finally, here is the link to Carol’s video on the Field Club’s YouTube channel.

 

D. Haines

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