Do birds have lungs?
Yes.
Bird lungs are compact and relatively rigid. They sit against the back of the body cavity and do not balloon in and out with every breath.
That is the first big difference from us.
The second is the air-sac system connected to those lungs.
What do bird air sacs do?
Think of the air sacs as flexible bellows.
They expand and contract as the bird breathes, helping move air through the respiratory system. Gas exchange happens mainly in the lungs, not in the air sacs themselves.
Many birds have nine major air sacs, although anatomy can vary among groups. Some of those sacs also connect with air spaces inside pneumatic bones.
That links this page nicely to do birds have hollow bones?
Does air move through bird lungs differently?
Very differently.
In mammal lungs, air moves in and then back out through many of the same passages. In birds, air flows through much of the lung in one direction.
That means fresh air can keep passing across the gas-exchange surfaces during both inhalation and exhalation.
It is a remarkably efficient system.
Why does one breath take two breathing cycles?
This sounds odd until you picture the air sacs as temporary holding spaces.
On the first inhalation, much of a parcel of fresh air moves toward the rear air sacs. During the first exhalation, that air is pushed through the lungs.
On the next inhalation, it moves toward the front air sacs. The second exhalation carries it out of the body.
Meanwhile, other air is entering behind it.
So one particular parcel of air takes roughly two inhale-exhale cycles to make the trip through the system.
Do birds have a diaphragm?
No mammal-style diaphragm.
Instead, movements of the rib cage, sternum, and surrounding muscles change the volume of the body cavity and air sacs.
This matters when handling birds. Restricting movement of the chest and sternum can interfere with normal breathing, which is one reason trained wildlife handlers are careful about how a bird is restrained.
Why do birds need such efficient breathing?
Flight is expensive.
Muscles need a steady supply of oxygen when a bird is climbing, migrating, hovering, or simply beating its wings through the air.
Birds also tend to run high body temperatures and fast metabolisms. A respiratory system that keeps fresh air moving across the lungs helps support that demand.
How can birds breathe at high altitude?
The efficient lung design helps, but high-altitude flight still pushes birds hard.
Species that routinely cross high mountains can have additional adaptations in their blood, muscles, and oxygen transport. Bar-headed Geese are a famous example.
Most birds never fly anywhere near those heights. Our how high can birds fly? page separates normal flight from the extraordinary records.
Do birds breathe through their beaks?
They can breathe through the mouth, but normal breathing commonly begins through openings called nares, which are the bird version of nostrils.
Most species have those openings somewhere on the bill. Kiwis are a memorable exception because their nostrils sit near the tip.
Read do birds have noses? for more on that anatomy. And yes, those nasal passages can trigger another familiar reflex: birds can sneeze.
Why does a hot bird pant?
Birds do not sweat the way we do.
Panting increases evaporation from moist respiratory surfaces and can help a bird lose heat. Some species also use throat movements called gular fluttering.
If you have ever watched a bird on a very hot day with its bill open, breathing can be doing two jobs at once: supplying oxygen and helping dump heat. See why do birds pant? for the cooling side of that behaviour.
Can birds breathe while flying?
Absolutely.
The whole system is built to support active movement. In fact, the mechanics of flight and breathing can work together as the chest and body move.
A hummingbird is an extreme example. Hovering burns energy at a furious rate, yet the bird still has to keep oxygen moving to those flight muscles.
Frequently asked questions
Do birds have two lungs?
Yes. Birds have paired lungs connected to a system of air sacs.
Are bird air sacs the same as lungs?
No. The air sacs help move and store air, while most gas exchange with the blood happens in the lungs.
Can birds breathe through their mouths?
Yes, although normal airflow commonly enters through the nares when the bill is closed.
Why do birds breathe fast?
Small birds in particular can have high metabolic rates, so their breathing and heart rates can be much faster than ours. Activity, heat, stress, and species all affect the rate.
Keep following the question
Bird breathing connects to flight, body temperature, and even hollow bones. Continue with the broad flight guide, how wings create lift and thrust, bird bone structure, or where a bird's nostrils are.