When a car door slams or a dog barks, you might notice the nearby birds jump with fright or even fly away. Clearly, they hear the noise, or else they wouldn't feel scared in the first place. But, now that you think about it, do birds have ears? And, if so, where are they?
Do Birds Have Ears?
Do birds have ears? Well, yes and no.
On the one hand, birds do not have external ears. Unlike mammals, who have external ear structures made of cartilage, bird ears are entirely internal.
But, with that said, birds technically do have ears. They have cavities in their skull and eardrums (yes, plural) that reverberate when sound waves enter these cavities.
So, again, do birds have ears? Yes, but not like our own.
Anatomy of a Bird's Ear...or Lack Thereof
After learning that birds do indeed have ears, you might find yourself sitting and pondering what these ears look like. After all, you've never seen a bird with ears perched on your bird feeder.
If you pull back the feathers along the side of a bird's head, generally a bit below the eye, you'll find a hole hidden underneath. While the feathers make this hole practically invisible from afar, it's definitely there.
The sight of a bird ear might seem alien at first, but it's not that unusual, at all. In fact, if you were to remove the external structure of a human ear, it would look much the same.
If you've ever been up-close with a baby bird, the ears are much easier to find. Without their full adult feathers, young birds often have their ear holes on full display. Of course, this changes as they reach maturity.
However, baby birds are just one example of a bird with highly visible ears. There are several species of birds whose adults have few or no feathers around their faces.
For example, you can see the outer edge of a vulture's ear just to the side and underneath its eye. Since vultures have very sparse feathers across their faces, their ears are on full display.
But don't be fooled by birds whose feathers mimic the appearance of external ears.
Many owls might look like they have ears extending above their heads, but this is just a tuft of feathers. However, owl ears are quite large for their head size, and some species even have vertically offset ears for more accurate hearing!
How Do Birds Hear Without True Ears?
So if birds have working ears, but don't have the outer cartilage we mammals do, is our external ear structure just for show? Not quite.
For mammals, the outer ear (also called the pinna) is responsible for capturing and directing sound waves into the actual ear canal. This structure helps us track the direction and distance of a sound's origin.
Without this external structure, though, birds lack much of this ability.
But why do birds have ears that can't tell from which direction a sound is coming? Isn't this ability especially important when flying in the air, since danger or prey could appear from almost any direction?
For years, scientists thought birds were unable to tell whether a sound came from one specific direction or another. Recently, though, we've learned that isn't at all the case.
While humans and other mammals rely on their external ear structure to locate the source of a sound, birds use their entire head.
To start, bird eardrums seem to be much more sensitive than our own. For example, a sound from the left will hit a bird's left eardrum with a different frequency than the right. In most cases, this tiny difference would be undetectable to our ears.
And when their ultra-sensitive eardrums aren't enough, scientists believe that a bird's extremely sharp vision then takes over. Once a bird has a general idea of where a sound came from, their eyes can lock on and do the rest.
Compensating with other senses
As humans, we tend to take the senses of other animals for granted. As far as natural life goes, our senses are all pretty middle-of-the-road. While this certainly hasn't been a disadvantage for us as a species, it does mean we have very little concept of other animal's senses and their strength.
Many birds, especially birds of prey, are famous for their incredible vision. However, eyesight isn't the only ability the bird family excels in:
Seeing is believing
Although you might not have known the answer to, "Do birds have ears?", almost everyone has heard the amazing facts about birds and their impressive vision. For example, the American kestrel can see an ant-sized insect from almost 60 feet away.
But distance isn't the only factor that makes bird vision so great. Since most bird species have their eyes on the sides of their head, many birds can see with almost a 360-degree field of vision. This is especially important for prey birds, who need to see predators coming from all directions.
However, this eyesight is no accident. On average, bird eyes are twice as large as mammal eyes when compared to their total body size.
Birds also have eyes specially adapted to their lifestyles. For example, robins and other birds that come out during the day have more cones in their eyes. Cones are more sensitive to colors and offer greater contrast during the day.
On the other hand, owls and other nocturnal birds have more rods in their eyes. Rods take in more light information, allowing these birds to see during the night's darkness.
Unlike humans and most other animals, many bird species can see ultraviolet light. In other words, the world looks completely different to some birds than it does to our own eyes.
And, if all of that wasn't enough, bird brains are better equipped to handle visual information. However, although it's unknown whether this comes as an advantage or a disadvantage, bird brains also process information from the left and the right eye differently (much like how humans tend to have a dominant hand).
Do you feel that?
Next to their top-notch vision, the other most interesting bird sense might just be their enhanced ability to feel vibrations.
Most, if not all, bird species have something called the Herbst corpuscle in their legs. To make things even more interesting, birds are the only animals to have this structure.
This structure is a collection of specialized nerve endings that detect vibrations. Although research on the Herbst corpuscle isn't very broad at this stage, it seems that birds can use these structures to actually locate the source of vibrations felt in their feet.
We know that many bird species, including pigeons, have these structures in their legs. For some birds, the reason for these nerve endings isn't entirely clear. For others, though, it is.
Scientists believe coastal birds use the Herbst corpuscle structure to feel shellfish and crabs underneath the sand. Similarly, woodpeckers may use their own Herbst corpuscle nerve endings to detect insects inside tree trunks.
These two examples show the incredible sensitivity of these nerve endings. In the future, it's very likely we'll learn even more fascinating uses for these and other unique bird anatomy.
What Humans Can Learn from Our Feathered Friends
If you spend your free time watching and identifying your neighborhood birds through your binoculars, it's normal to ask questions like, "Do birds have ears?" In fact, learning the answers to questions like this can help you understand your feathered friends and the incredible science behind much of their anatomy.
While the ability to fly might be the first thing you think of when it comes to interesting bird facts, these creatures are actually a treasure trove of scientific discovery just waiting to happen.
For example, woodpecker heads have inspired innovations in concussion prevention and industrial shock absorption. And with so many unique bird species out in the wild, these inspirations are certainly just the tip of the iceberg.
Do you have any interesting bird facts you'd like to share? Or a story about how a bird used one of its senses with incredible results? Please share your stories in the comments below!