Anatomy – Page 2 – Owl Chatter

Owls are known for their extremely impressive auditory skills. Their hearing is so acute that they can hear certain sound frequencies that other animals, such as humans, cannot hear. For example, Barn owls have been known to use frequencies above 8.5 kHz to strike their prey. Therefore, this acute hearing enables owls to hear the slightest movements of their prey through undergrowth. It is vital for owls to have extremely sensitive and acute hearing because they often hunt at night and therefore rely on sound more than sight for this. Owls can catch prey in complete darkness if they are in an area that they know well in the light. The owl can use its memory of the areas visual and then turn its head towards any sound they hear in complete darkness and this is enough to enable them to successfully strike. Therefore, it can be argued that the owls hearing is its most vital sense, especially for owls such as the Great Grey Owl and Snowy Owl, who hunt mammals under a layer of snow, so sight alone will not help them here, so they rely almost solely on hearing. So, to answer the question 'Do Owls Have Ears?' yes owls do have ears! They are located on each side of the owl’s head, behind the eyes and they are more like a hole in the head rather than an ear. These holes are covered over by feathers therefore they are seamless with the owl’s head. It can be misleading on some owls that have 'tufts’ because these resemble ears but are simply just feathers. Owl tufts that can be mistaken for ears! Anatomy of the Ears Owls ears are asymmetrically set on the owls head for hearing purposes. This is more obvious on the strictly nocturnal species, where the right ear will be higher than the left. This is so there is a slight delay from when the sound hits one ear compared to the other and this helps the owl to pinpoint where the sound is coming from. The flat face of the owl helps sound to flow off the face and into the ear canals. The opening of the owls ear is known as the aperture, and in some species there is also a valve inside this opening known as the operculum. The aperture varies in shape depending on the owl species, Tytonidae species have rounded opening with a large operculum whereas the Strigidae species have varied shaped apertures. The sound enters the ear in the form of a pressure wave which head towards the eardrum. Fun fact - owls actually have pretty large ear drums in comparison to other birds, and it is through this ear drum that these sound waves are transformed into what is called ‘fluid-borne vibrations’ which cause all the little hairs in the inner ear to become alert. Different sound frequencies will affect different parts of the ear and cause different hairs to move. This all combined creates a picture within the owls mind of where this sound is coming from. In some owl species, the asymmetry of the ears is actually visible in the temporal part of the skull structure. Owl skull structure showing the asymmetrical ears. Image from BTO Owls can tell the direction of a noise by paying attention to the minute time difference between when sound reached one ear, compared to the other. If a mouse is walking around in the undergrowth to the lower right of an owl sat in a tree above, the right ear would hear this sound just before the left ear picks up this sound. This tells the owl where the sound is, the owl will then turn its head towards the sound and if they are correct in locating the direction, further sounds will reach both ears at the same time, this tells the owl the prey is right in front of them. It has been estimated that the time difference is 30 millionths of a second, yet this is enough time to tell the owl what they need to know! Of course though, this isn't enough to catch the mouse. The owl knows the direction of the mouse, but how do they know how far away (high and low) the mouse is? Since the ears are not symmetrical, the left ear is higher than the right ear, so a sound coming from directly below will reach the right ear first. The owl then does it owns calculations extremely quickly within its brain to create the mental image of where that mouse must be. The owl will aim towards the last sound the prey made and if they suddenly change direction, the owl can figure this out mid flight. The part of the owls brain that creates this mental image is called the medulla and this part of the brain is associated with everything to do with hearing. The medulla is extremely complex and high functioning and has at least 95,000 neurons constantly buzzing away, this is 3 times as many as most other species of bird. I hope this has provided you with enough knowledge to understand that owls do in fact have ears, and how important these ears really are for the owl. even though we cannot easily see them, they most definitely exist as one of the most vital parts of what makes an owl so great at what they do - hunt!