You really can see an owl’s eyes through its ears

June 11, 2013 • 8:24 am

When we (Matthew was complicit!) recently posted a photo showing that you could see the rear of an owl’s eyes through its ears, some confusion ensued, and we didn’t know whether that photo involved removing part of the owl’s ear to expose the inside of its head. So the burning question remained: can you really see the back of an owl’s eye through its ears?  We now have the answer.

Thanks to an alert reader, Dr. Kelly Williams of the Department of Biological Sciences at Ohio University in Athens, we’ve learned that the original post was indeed correct. If you peer into an owl’s ear-hole, at least in a saw-whet owl, you can see its eye. Kelly sent an email and photos documenting this amazing fact (reproduced with permission):

Just thought I’d give some info on the photo of the external ear and eye of the owl picture that was posted. The hand holding the owl [JAC: in the original photo] is mine and the owl was indeed alive and flew off just fine. We host several hundred visitors each year to our Northern Saw-whet Owl fall migration station and frequently gently part the feathers (as you saw in the photo) to show people the asymmetrical ear openings. I’ve attached my own photos (so not my hand this time) that show each side. Saw-whets are one of 3 species of owl in NA that have an asymmetrical shape to their external auditory meatus (several species have one ear higher than the other – like the barn owl). In Europe, I believe a greater proportion of owls have this asymmetry. The eye is supported by a sclerotic ossicle.

I believe the picture that was posted was taken by Jim McCormac—more photos and information are at his blog. (If you think the ear and eye are neat – check out the black light photos of the wing that fluoresce pink due to the porphyrins).

Here it is: an unretouched and intact living owl. The eye is clearly visible through the earhole:


And here’s the lovely creature itself, looking a bit peeved (but owls always look peeved):


And here are two pictures from McCormac’s website, Ohio Birds and Biodiversity. The first shows the wings fluorescing pink, the second the total cuteness of these tiny owls (the Linnaean binomial is Aegolius acadicus).



Finally, here’s one of Kelly’s PowerPoint slides showing the asymmetry of the saw-whet skull. It’s quite striking. I’m pretty sure it’s directionally asymmetrical; that is, it’s not random which ear is up and which is down. But that raises the question of how, during ear development, the skull “knows” which side is right and which is left.  (By “knowing”, of course, I mean that there must be some biochemical/genetic cues that distinguish right from left.)Picture 3

17 thoughts on “You really can see an owl’s eyes through its ears

  1. I suppose the asymmetry might help in locating prey? Stronger and weaker sound from left right and up down.

    1. I read a SciAm article, years ago, about this. I’ve long forgotten the details, but indeed the asymmetry in the ears functions in direction localisation (as do IIRC, the eye sockets and the eye-feathers — the shape picks up sound like a parabolic dish does).

    2. It’s for discrimination in the vertical plane only. sounds from above or below will reach the ears out of synch, while sounds at ear height will be in synch.

    1. Gregory C. Mayer commented about that in a previous topic:

      For example, you can detect your finger moving back and forth beside the left ear by looking into the right ear.</blockquote.

      Oh wait that was specified for a lizard but, lizards and christians are close enough anatomically in the cranial area aren't they?

      My pre-apologies to all offended lizards per jesperbothpedersen1's observation.

      1. Probably obvious, the last two paragraphs are mine not Greg’s, so shouldn’t have been indented.

      2. “My pre-apologies to all offended lizards per jesperbothpedersen1’s observation.”

        I’m sure the Lizards can regocnize and forgive the good natured humour in your post.

        Arhg, there be dragons!

  2. What a cute owl! I love owls and the owl looks way happier in the second to last picture. 🙂

  3. Jerry has provided several examples of production of asymmetrical patterns being produced in biology. The reversible train movement was another. Making decisions may be another. Visual reversal of cube patterns is another. I wrote a paper back in 1975 providing a simple biochemical model for this.

    David Park, Flux Induced Biochemical Differentiation, J. Theor. Biol, (1975) 54, 363-379

    It showed how a temporal flux pattern (say a gene being activated over time) could generate a spatial pattern. I don’t know if this mechanism is actually operative anywhere in developmental biology. Maybe not. Being immersed in an environmental gradient is the more standard explanation.

    For those who have access to up-to-date Mathematica I have a notebook with lots of graphics and animations that illustrate the process. (It also requires a Mathematica package Application that I sell but if you are a serious academic and interested I will provide it to you.)

  4. The see-through skull is an illustration of the powerful selection for lightness in these small owls, I think. Every bit of bone that can be dispensed with apparently has been.

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