From New Mexico Wildlife Center
There’s a cool secret hidden behind the flat facial disc of a Northern Saw-whet Owl: absolutely enormous ears!
While Northern Saw-whet Owl 24-988 was sedated for a bandage change recently, we parted the feathers at the edge of her facial disc to show one of her ear openings.
This species has asymmetrical ears - one placed higher than the other - which gives them the ability to hear in three dimensions! We humans, with our symmetrical ears, can judge pretty well how near or far a sound is and whether it’s coming from our left or our right, but it’s difficult for us to tell whether a sound is coming from up high or down on the ground.
That’s not a problem at all for a Northern Saw-whet Owl, since they can notice in an instant when a sound coming from down low reaches their lower ear a fraction of a second before it’s detected by their higher ear.
Those ear openings are so large that it’s possible to see the back of an owl’s eye through the ear hole. See that darker, bluish-grey structure in the ear? That’s the back of 24-988’s right eye!
Owls’ eyes are also enormous - each one about as big as their entire brain - which allows them to see very well in the dark, but it also means that when an owl sustains a head injury, there’s also a high likelihood of injury to one or both eyes.
When we do an intake exam on an owl, we often look into the ears to check for bruising on the back of the eyes. In 24-988’s case, she did have a minor injury to her right eye, which healed quickly with medication.
Her ears and eyes look great, and her fractured femur and scapula are also nearly healed!
I wouldn’t be surprised if they can actually hear the fish, especially if they’re hunting in shallow water like this. It seems like not too much is known about fish owls, but owls in general have a similar hearing range as us (200 to 12,000 Hz for them, 20 to 20,000 Hz for us). So if people can hear the fish moving around, it would seem like the owls could too. And they’re better at picking up quiet sounds. (Article is long, ctrl+F “faint”.)
I would definitely be curious to try an owl’s hearing on for size. I don’t have trouble telling if sounds are coming from high or low, but I would bet their ears can do it better, or different. But it’s pretty amazing what even human ears can do. Like this story about how native people in Brazil can “hear the fish singing.” Sounds kind of crazy, maybe, but sometimes you just have to listen closely to hear things.
The article with the fish songs was very interesting! I found a brief video of a lady studying fish voices that gave some examples.
I’ve read a good bit of the other article’s study by Payne and Friends and did my version of an ELI5 about it here before. The Payne family comes up every time bioacoustics is brought up, and I really need to get to some of their books at some point. The first portion of the article was fun, as it seemed a bit more simplified than the research papers, but then it got into the same more expert language and I got lost on anything deeper than what I’d already translated for myself previously.
If you can appreciate the details of that one more than I can, when looking for a list of owls with symmetrical vs asymmetrical ears, I found this paper testing frequency response and what sounds they hear best if you want to take a look at that.
This chart from this paper lists the Brown Fish Owl as symmetrical, along with the GHO and Screech among others, and the Burrowing and Little Owls are also symmetrical. There looks to be a lot of owls listed as asymmetrical that aren’t when reading less technical sources, so it was a bit tricky to find something that seemed completely reliable.
Thanks for the reads! Things like this really remind us how much about our own world we still don’t know and have to look forward to discovering!
I read the first and last couple pages of the article. It starts to make my head hurt at some point, but I get the gist. I thought it was interesting that the feathers over their ears are designed to let sound through. And owls with asymmetrical ears tend to be better at hearing higher frequencies. Which seems to be because they have more space in their inner ear, and more tiny hairs that can amplify or transmit the sound.
The fish sounds were interesting too. It sounds kind of like the deeper sounds might be coming from the swim bladder. Off topic but fun fact: the swim bladder can change during the breeding season so it’s easier to make mating calls for hours on end.
Lol horny fish.
It seems they still didn’t have much of an idea why some owls have the extra internal skin flap in the ear canal. I love they’re still keeping so many secrets from us!
I figured the flaps would be to keep dust and things out of their ears, but apparently they can be moved to help focus or filter sound. Source 1 (easier to read). Source 2 (more technical). Ctrl+F “flap” in both articles.
I saw a couple places that said closing the flaps can block out noise while the owls sleep.
It would make sense if you had super hearing that there would be situations where you may want to have a damper for that power. My head hurts too much from not feeling good to read the articles yet, but I did skim them a bit and there’s some really good flap pics in there! Thanks for sharing them. You’ve been bringing a lot of great stuff to me this week and I appreciate it!
I’m pretty sure I have better than average hearing, and it does get a little tiring sometimes. Whether it’s high-pitched background noise, or turning on the good equipment and listening to something I like. It’s work to process a lot of sound.
I like researching things, seeing the pictures, and reading the stories here. Always a small highlight that brightens my day. Had some headaches too this week, not fun. Hope you feel better soon :)