Birds have ears, just like humans and other animals do. However, unlike many mammals, a bird’s external ears are not visible. This leads many people to ask: why can we not see a bird’s ears?
There are several reasons that explain why birds’ ears are not noticeable:
Ears Are Small and Covered by Feathers
A bird’s external ears, known as the pinnae, are very small. They are simply small openings on each side of a bird’s head, hidden by the bird’s feathers. Unlike the large, prominent ears of mammals like rabbits or cats, a bird’s pinnae are tiny and difficult to see. Their small size makes them virtually invisible under the layer of feathers covering a bird’s head.
Ears Lack Cartilage
In mammals, the large, flexible pinnae are composed of cartilage, which gives them their distinctive shapes. A bird’s pinnae lack cartilage, so they do not have the structure to stand out from the head. Instead, the openings are just small holes surrounded by feathers.
Birds Don’t Need External Ears
Mammals rely heavily on their external ears to collect and funnel sound into their ear canals. Birds’ ears work differently. They do not need large, prominent ears to collect sound waves.
Bird Ear Anatomy
To understand why we can’t see bird’s ears, it helps to know a little bit about their underlying ear anatomy:
Small Openings on the Side of the Head
As mentioned, birds have a small external opening on each side of the head called the pinna. These openings lead into the bird’s ear canal, which leads to the middle ear.
Ear Canal
The bird’s ear canal is short compared to a mammal’s ear canal. It runs just a short distance before opening up into the bird’s middle ear.
Middle Ear
Deep inside a bird’s skull is the middle ear chamber, containing a structure called the columella. This serves the same sound transmission function as the three tiny bones in a mammal’s middle ear.
Inner Ear
Finally, sound reaches the inner ear, where sensory cells convert the sound into neural signals that are sent to the brain. A bird’s sense of balance is also controlled in the inner ear.
Birds Hear Differently Than Mammals
Birds are able to hear well without noticeable external ears thanks to key differences in how they process sound:
Head Movements
Birds bob and turn their heads to help funnel sound into their ear openings. Their small pinnae openings are all they need to detect sound coming from different directions.
Specialized Feathers
Some birds have clusters of feathers around their ear openings that may help reflect sound in. Owls in particular have concave feathers that may amplify faint sounds.
Keen Inner Ear
While mammals rely heavily on their external ears, a bird’s inner ear does most of the work in hearing. Birds have specialized sensory cells and neural connections that make their sense of hearing very acute.
Better Hearing at Higher Frequencies
Birds can hear higher frequency sounds much better than mammals can. They can discern pitch differences that humans cannot detect. This helps them communicate through bird calls and songs.
Advantages of Hidden Ears
While birds lack visible ear structures, their streamlined head shape provides some advantages:
Aerodynamics
Without protruding ears, a bird’s head is very smooth and aerodynamic. This helps minimize drag when a bird is in flight. Visible ears could disrupt airflow and cause turbulence.
Protection
The small openings are protected by feathers, keeping debris out of the ear canal. Ears are also safely tucked away during fights between birds.
Temperature Regulation
Without exposed ear structures, birds can better retain body heat and stay warm. Lacking ears also prevents heat loss in cold climates.
Streamlined Appearance
The smooth, sleek head shape of birds is considered more aesthetically pleasing by some. It adds to their appeal as beautiful animals.
Exceptions: Birds That Do Have Visible Ears
While most bird species do not have noticeable external ears, there are a few exceptions:
Owls
Owls have feather tufts that resemble mammalian ears. These likely evolved to improve sound detection, but are not true ears.
Parrots
Some parrot species have areas of bare skin around their ear openings, making them slightly more visible. However, the openings themselves remain very small.
Penguins
Penguins’ ears stick out slightly from their smooth heads. This minimal protrusion may enhance their underwater hearing.
Storks
A stork’s ears can be seen as small notches on the sides of the head when feathers are pushed aside. Their ears are slightly more pronounced than those of most birds.
Conclusion
In summary, birds do have ears, but they are small openings on the sides of the head that lack protruding structures. They are covered by feathers, leaving them virtually invisible in most species. Birds are able to hear very well despite this thanks to adaptations like head motions, specialized feathers, and keen inner ear anatomy. While a few bird species have slightly more pronounced ears, the majority keep them discreetly hidden. So the next time you see a bird cock its head as it listens intently, know that it is hearing you very well with its concealed ears!