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Bird Anatomy – All You Need To Know

Bird anatomy

In order to properly identify birds, you first need to know their anatomy. Below, we’ve listed the basic anatomy of birds. Some of these terms will be appropriate for one bird but not another. For example, some birds have wing bars, eye rings, and crests, while others don’t.

Bird anatomy is different than the anatomy of almost all mammals. Birds have two wings and hop on two legs. Additionally, birds have beaks instead of jaws with teeth and feathers instead of hair.

However, that doesn’t mean they aren’t like us in a few ways. Birds are warm-blooded and have a body temperature of around 104°F or 40°C. This is a few degrees warmer than a lot of mammals. Birds also have two ears and two eyes, just like us.



We’re going to start with the head. This is because it’s one of the first places you should look for defining marks to help with identification. The top of a bird’s head is called the crown, and the back of the bird’s head is called the nape. These are critical parts of a bird’s head that can help you pinpoint a bird.

Varied Thrush

Varied Thrush. Note the orange stripe starting on the head.

Here are some defining marks that you can take a look at to help you identify a bird:

  • Absence or presence of a crest.
  • Crown stripe. The crown stripe is a line that goes through the midline of the head.
  • Eyebrow stripe. This is also known as the superciliary. The eyebrow stripe is a line that goes over the bird’s eye.
  • Eyeline. The eyeline is a line that goes through the eye.
  • Eyerings are very noticeable marks. It’s a ring of color around a bird’s eye.
  • Eye color, the color of the iris, can also be very useful for identification.
  • Malar stripe, also known as whisker mark or mustache.
  • Some birds have throat patches. These are distinct and can really help you narrow down a species along with other features.
  • The color of the lower and upper beak.
  • Color of the lore. The lore is the area between the eye and the base of the beak.



Short-billed Dowitcher

Photograph © Glenn Bartley.

The shape, color, and size of a bird’s bill are crucial for identification. Bird bills can vary greatly, so be sure to keep an eye out for other standout features like bands on the bill, different colored bills, curvature, etc.



The chin of a bird is where our chin is. It sits directly below the bird’s “mouth” (bill). It’s not easy to see the chin on many birds. However, in some cases, birds will have a chin that is a different color than the rest of their body. This can be extremely useful for identification when this is the case.



Male and female swans

Swans have noticeable nares.

Nares are essentially a bird’s nostrils. These are external openings of a bird’s respiratory tract found on the sides of the beak. In some bird species, nares are covered by feathers, making seeing them challenging.

Nares function like human nostrils, they filter the air that bird’s breathe.


Northern Cardinal

Northern Cardinals are known to raise their crest when they feel threatened or are agitated.

The crest is a group of feathers that some bird species have on top of the head. Crest feathers can be permanently up or move up and down, depending on the species. The crest is not the same as the crown. The crown is just the top of a bird’s head. Not all birds have a crest, but all birds do have a crown.



The nape is the back of a bird’s neck, just like humans! However, the mantle is something that gets mistaken for the nape. The mantle on birds is the feathers on the bird’s back just below the nape of the neck.



Little Blue Heron

Copyright Glenn Bartley

It’s hard to see a bird’s neck. Many species have relatively short necks making them insignificant. However, wading birds, like cranes, herons, and egrets, have very prominent necks, making them a great feature for identifying birds.

Additionally, the length of a bird’s neck can help distinguish between different bird species. To put this into perspective, swans have many more vertebrae in their necks than parrots do. Swans have 25 vertebrae in their necks, while parrots have 9.



The chest, also known as the breast, is the upper part of a bird’s body between the abdomen and the throat. A bird’s chest can be a different color than the rest of its body or have spots, streaks, or stripes that can be very helpful with identification.



The abdomen, also known as the belly, extends from the undertail coverts to the bottom of the bird’s chest. The abdomen is a great feature to look at for identification because markings and colors on this area may vary from flanks to chest.



Cedar Waxwing

A bird’s flanks are essentially its sides. The flanks are located between the abdomen and the underside of the wings. A lot of bird species have unique markings or colors on their flanks. However, we would like to mention that the flanks can be hard to see on some birds due to how they carry their weight.



Birds’ backs are easy to see when a bird is in the right posture and tend to be broad. Be sure to look for different markings and colors on the back that are easily distinguishable from the wings, rump, and neck.



A bird’s rump is a patch low on the back and above the tail. The rump doesn’t stand out on many birds, but some bird species show unique color patches on their rumps that can be extremely helpful for identification.



scissor-tailed-flycatcher-in-flight - Lora render

Just like other bird features, their tails are crucial for proper identification. Birds can hold their tails in various positions and often have different positions for flying and perching.

Tails are not needed for flight, but they do allow birds to have more control. A bird’s tail lowers the LID, also known as the lift-to-drag ratio.

The tail also helps birds maintain stability during different flight speeds and generates lift to help with slow flight and turning.



Birds’ wings can be very distinct. Birds like vireos and warblers have wing markings that can help you identify them. Other bird species, like sparrows and flycatchers, don’t have wing markings which can also help with identification. Birds like raptors, shorebirds, ducks, and others have distinctive wing markings that can be seen in flight.

Keep an eye out for these field markings:

  • Wingbars. These are stripes that can be seen across the wing when it’s folded.
  • Wing patches. These are blocks of color that can be seen on the wing.
  • Wing tips can vary in color, helping you pinpoint what bird you’re looking at.
  • Wing lining. The wing lining involves the feathers that cover the underside of the wing.
  • Primaries. Primaries are the long-flight feathers on the outer portion of the wing.
  • Secondaries. Secondaries are the flight feathers on the inner portion of the wing.
  • Speculum. The speculum is a patch of colored secondaries. These are common in ducks, so be sure to look for them when identifying a bird of this species.


A bird’s wing consists of wrist, elbow, and shoulder joints. These establish the basic shape of the wings and allow the birds to have a range of motion.

Primary, secondary, and coverts cover the skeleton, stabilize flight, and provide lift. Flapping is a common thing birds do. This movement helps birds push themselves through the air.

On the downstroke, the air is forced down, which pushes the bird up. While this happens, the wing’s tip tilts forward, pushing air back. As I’m sure you guessed, this propels the bird forward.

Small birds flap their wings in fast bursts, while larger birds flap slowly and glide wherever possible.

Bald Eagle taking off



There are many different shapes of bird feet. There are climbing feet, swimming feet, running feet, perching feet, grasping feet, and scratching feet. Climbing feet can be seen on birds like woodpeckers. These feet have back toes, so they don’t topple backward and help them climb wood.

Swimming feet can be found on birds like ducks, and they’re webbed. These feet allow birds to paddle through the water. Running feet can be seen on birds like emus and ostriches, with all the toes facing forward.

Perching feet are common in our backyard birds. They have four toes, one in the back. These help them perch on trees and balance. Grasping feet can be found on raptors, like hawks and eagles. These feet are clawlike and allow the bird to grasp their prey.

Lastly, we have scratching feet. Scratching feet can be found on birds like chickens. These feet have four toes with sharp claws that help them dig in the ground. Many feet are the same color as a bird’s legs, but there are always exceptions.

Nuttalls Woodpecker


Bone Structure

Bird bones are lighter than mammal bones. In fact, some bones act as part of the avian respiratory system and are hollow!

Bones that are a part of the respiratory system are called pneumatic bones and include the humerus, skull, clavicle, keel, lumbar and sacral vertebrae, and pelvic girdle.

The wings and bill are part of a bird’s skeleton. The bill is composed of two bones. The upper beak, also known as the premaxillary bone, and the lower jaw, also known as the mandibular bone.


Anatomical differences

Birds have several anatomical differences from other animals. For example, unlike most mammals, birds have:

  • Birds don’t have a diaphragm. This means their abdomen directly communicates with the lungs, thorax, air sacs, and heart.
  • Birds have a variety of pneumatic bones. This just means that the bones are filled with air. These bones communicate with the thorax and abdomen.
  • Birds have complex air sac systems that spread through their entire body with a complex one-way airflow. This means birds breathe in two cycles before the air is exhaled back out.
  • Birds can’t be “strangled” due to their complete cartilaginous tracheal rings. This means that birds have no soft spots in their trachea. However, mammals have tracheal ligaments that can collapse.
  • Respiration is accomplished by the free chest and abdomen movements. This means that a minimal amount of internal lung movement happens.
  • Female birds are able to store additional calcium in their normally hollow bones before laying eggs.
  • Birds have very flexible and long cervical spines. Mammals have an average of seven cervical vertebrae, while birds have anywhere from 11 and 25. This is demonstrated by how well birds can reach almost any body part with their beak to preen and turn their heads.
  • Of course, birds have the ability to fly. However, they don’t have a lot of coordination on the ground.
  • Birds don’t have any teeth.


Frequently Asked Questions About Bird Anatomy

What are the 7 main characteristics of birds?

The 7 main characteristics of birds are:

  • they lay hard-shelled eggs
  • feathers
  • a unique respiratory system
  • beaked jaws with no teeth
  • high metabolic rates
  • lightweight yet strong skeletons
  • four chamber hearts


Do all birds have the same anatomy?

All birds have the same basic skeletal structure and body design. However, these can vary slightly in shape and size based on the species.

What muscles allow birds to fly?

Birds use their pectoralis muscles to fly. These muscles move the humerus bone in the wing that fits around the shoulder.

Do birds have teeth?

No, birds do not have teeth.

Why don’t birds pee?

Birds excrete their nitrogenous wastes in the form of uric acid. Bird pee and poop come from the same place at the same time. The white part of their excretion is the uric acid, and the green or brown spotting you see in the white portions is their poop.

Do birds control when they poop?

Birds can control the flow of their poop, but they don’t have as much control as mammals.

Do birds feel pain in their feet?

Birds have very few pain receptors in their feet. So, it’s theorized that they don’t really feel pain in their feet.


Read next: How do birds reproduce?

About the Author

Brianna Goulet

Brianna loves to get outdoors for everything creative and fun. She has a passion for birds and is a hobbyist wildlife photographer based in Central Florida. Her goal is to share everything you need to know about birds so you can get out there, explore, and identify confidently!

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