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Since owls are mainly active at night, they feature a highly developed hearing system. An owl’s natural ears are found on its head sides, just behind the eyes, and are covered by the facial disc’s feathers. The ear tufts visible on some species are simply feathers, not ears.
Although owls don’t have the same floppy ears as humans do, they can still hear their prey with precision even under a dense layer of snow. An owl has very good hearing. Structure of an Owl Ear
An owl’s ear has three visible parts: the inner ear, middle ear, and inner ear.
The shape of the ear opening, called the aperture, depends on the owl species. The ear, in some species, has a valve known as operculum covering it. The opening may be a small, round aperture or an oblong slit with a large operculum.
All the Tytonidae family owls feature circular openings with wide opercula, while in the Strigidae family, the outer ear shape is more diverse.
An owl’s range of clear sounds is like that of humans, although an owl’s hearing is much sharper at specific frequencies allowing it to hear even the slightest movement of its prey in undergrowth or leaves.
Some owl species, particularly nocturnal species, such as the Boreal owl or the Barn Owl, have asymmetrically set ear openings. These species feature a powerful facial disc, which acts as an aerial disc, directing sounds into the ear openings. The shape of the disc can be changed at will, using particular muscles.
An owl uses uneven ear openings to locate a target through ground covers such as foliage, leaves, or even snow by listening to the prey movements. When an owl hears a noise, it can tell its direction due to the minute time difference in which sound is felt in the right and left ear. For instance, if a sound is to the owl’s right ear, it would hear it before the left ear.
The owl then adjusts its head so that the sound reaches both ears simultaneously. Then it perceives a prey is right in front of it. Owls can detect a left/right time difference of around 30 millionths of a second (0.00003 seconds).
In addition, an owl can tell whether the sound is low or high by using uneven or asymmetrical ear openings. For instance, in a Barn Owl, the left ear opening is higher than the right, so a sound originating below the owl’s angle of sight will be louder in the right ear.
The adaptation of up, down, left, and light signals are combined right in the owl’s brain and create a mental image of the space where the sound source is located. Studies have found that the medulla of an owl’s brain is much more complex than in other birds. A Barn own’s medulla is estimated to contain no less than 95,000 neurons, three times more than a crow.
After an owl has detected the direction of its potential target, it will fly towards it, maintaining its head in angle with the direction of the last sound the prey made. If the target moves, the owl can change directions in the middle of a flight.
When around 24 inches from the prey, the owl will bring its feet forward and spread its talons to an oval shape. Before striking the target, the owl will thrust its legs out in front of its face and usually close its eyes before the prey.
Owls have excellent hearing when it comes to catching their prey at night. The combo of ear location, pinpoint accuracy, and sound frequency, and pinpoint accuracy certainly gives an owl better hearing than humans. They don’t have the same sound range as humans, but they certainly have what they require.
Studies have shown that once an owl, particularly a Barn owl, knows its way around an enclosure, it can catch a live free-running mouse in completely dark areas, using its hearing alone and with no sight.
Owls can work an incredible trick with their hearing on two counts. First, their hearing range matches their prey’s, so they can accurately hear everything their kill says, making them very easy to detect and hunt out.
Second, owls can fly at a particular speed, much slower than other birds, and their wings’ vibration produces a noise that neither themselves nor their kill can hear. That is a hunting skill that makes them super stealthy and smart. In addition, if they are moving their wings at a too fast speed, they can hear it, so they know to slow it down again.
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Hearing can be even more essential for species like the Great Grey Owl, which you can often see taking small animals active under a thick layer of snow. The owl does not have a chance to see the small mammal in such a case, so it must rely on its hearing instead.
Featured Image Credit: StockSnap, Pixabay
Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.
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