How Do Birds Breathe? (Everything Explained)

The respiratory systems of birds are somewhat different from those of humans and need to work efficiently, even at high altitudes where the air is less oxygenated. To sustain flight, a bird’s muscles and blood need a constant supply of oxygen.

But how does a bird’s respiratory system work? Read on as we take a closer look at how birds breathe.

Air flows into the bird through nostril-like openings in the beak, travels through the trachea, posterior air sacs, lungs, and anterior air sacs, before exiting again through the trachea. Gas exchange occurs in the lungs, where carbon dioxide is exchanged for fresh oxygen.

Birds require a greater constant supply of oxygen than humans, and the two-way airflow system used in human lungs and alveoli cannot provide birds with the amount of oxygen they need to maintain their ultra-fast metabolic rate.

A bird’s respiratory system makes up about 20% of its internal volume compared to about 5% for humans, but the network of lungs and air sacs work efficiently to provide the bird with enough fresh oxygen to be able to fly and sing at the same time!

Read on to learn more about bird respiration and how it takes two breaths, not one, to circulate air through the air sacs and lungs of a bird’s respiratory system.

A close-up of the goose’s beak, showing the two “nostrils”

How does a bird’s respiratory system work?

Breathing in birds begins with the nostrils, which are located on either side of the base of the beak and serve a similar function to the nostrils (in the case of kiwis, these openings are located at the tip of the beak).

From these openings, inhaled air travels in one direction through the bird’s trachea, into the air sacs and network of lungs, and back through the trachea.

By looking at the breathing cycle and each of its components in turn, we can get a complete picture of the ins and outs of a bird’s breathing.

breathing cycle

A bird takes two breaths to complete a complete breathing cycle. Here’s a summary of how it works:

• Inhalation: Air flows in from the nostrils, through the trachea, and fills the rear air sacs.
• Exhale: The air leaves the air sacs and enters the lungs, where it is moved by the contraction of the chest muscles. Gas exchange occurs in the lungs, where waste carbon dioxide is exchanged for fresh oxygen.
• Inhalation: Air leaves the lungs and flows into the front air sacs.
• Exhale: Air enters the trachea from the anterior air sac and exits the beak through the nostrils.

air bag

Most birds have a total of nine air sacs: four pairs of air sacs (posterior: two abdominal, two posterior; anterior: two anterior, two neck) plus one unpaired (interclavicular) air sac. Freshly inhaled air enters the posterior air sacs before being transferred to the lungs, then moves to the anterior air sacs, and exits the trachea.

the lungs

The lungs of birds are constantly inflated by air sacs, which act like bellows. The vital role of the lungs is to bring oxygen into the blood to meet the metabolic needs of the bird and to remove waste carbon dioxide from the bird through the process of gas exchange. This process of gas exchange between the lungs and blood takes place in tube-like structures called accessory bronchi.

Diagram of a bird’s respiratory system

How do birds breathe without a diaphragm?

Human breathing relies on the diaphragm to move air in and out of the lungs. The respiratory system of birds works in a different way, using muscle movements to expand and contract body cavities to move air through the lungs and air sac system.

Do birds have lungs?

Birds have two relatively small lungs. These stiff lungs are kept inflated by airflow in a network of air sacs. A bird’s respiratory system works efficiently to ensure that the bird’s lungs are constantly supplied with fresh air through tube-like structures called parabronchi that allow enough oxygen to freely enter the blood.

The northern goshawk calls, exhales visible on a cold morning

How Do Birds Breathe While Flying?

Flying birds consume significantly more oxygen than resting birds. When flying, birds adjust their breathing rate so that they take more breaths per minute instead of taking in more air.

Can birds hold their breath?

Waterfowl, such as cormorants, terns, puffins and gannets, often need to fish on the surface of the lake or below the surface of the sea.

While they can’t breathe underwater, they have more oxygenated blood, are good for diving and swimming, and can hold their breath for short periods of time without inhaling additional oxygen.

Some ducks can submerge their heads in the water for a short time before needing to resurface and breathe.

According to the research, it is known that non-aquatic birds cannot consciously control their breathing like humans and cannot hold their breath for long periods of time through the breathing process due to the need to constantly remove carbon dioxide from the blood.

black cormorant diving for fishing

How long can birds hold their breath?

Several species of waterbirds can hold their breath underwater for long periods of time, allowing them to dive deep to the surface and swim to find and catch prey. These birds can hold their breath for 3 to 10 minutes before needing to resurface to breathe.

Gannet is a seabird that has been fishing in the deep sea for a long time. It has evolved to have no external nostrils on the beak, and the opening of the respiratory system is located in the mouth. Gannets can swim underwater for more than 15 minutes without needing to breathe.

Gannets have the incredible ability to swim underwater for 15 minutes without holding their breath

How Do Birds Breathe While Sleeping?

Breathing is an involuntary act for birds, and the regular breathing cycle continues whether the bird is awake or asleep. Resting birds have lower oxygen requirements than birds in flight, so their breathing rates will naturally be lower.

Many birds sleep with their beaks tucked into the feathers of their backs or wings to conserve body heat and maintain body heat.

Tightening their nostrils (nostril-like structures on the beak) close to the body allows the birds to breathe air warmed by their own body temperature and maintain a steady temperature while they sleep.

How many times do birds breathe per minute?

On average, a resting person breathes about 12 times per minute. For birds, this ratio varies by species and is lower for higher body weight birds. Larger birds such as bald eagles breathe 18 times a minute, while canaries take 60 to 100 breaths. The resting breathing rate of an ostrich is only 5 or 6 breaths per minute.

A large bird like the common vulture takes about eighteen breaths per minute

Do birds breathe through their mouths?

On either side of the base of the beak are two small holes called nostrils. They function effectively in the same manner as the nostrils, forming the external entrance to the bird’s respiratory system. Air flows through these openings in the beak into the bird’s trachea, where it travels to the air sacs and into the lungs.

Do birds have gills?

Birds do not have gills. Even aquatic birds that spend long periods of time underwater, such as penguins, lack gills. Instead, all birds breathe by absorbing oxygen from the air using their lungs and air sacs.