Unlike many other animals, birds don’t have a visible air and odor intake system. And by that, we mean a nose!

When birds breathe, air passes through small nostril-like openings in the beak called nares. When you look beyond the familiar nostril concept and explore what happens next, a bird’s breathing system looks surprisingly different from that of a mammal. That’s because in order to handle the physical demands of flight, birds actually have a super-efficient respiratory system to oxygenate their blood (which gives their flight muscles energy).

First, think of the human respiratory system. As you know, air flows into the lungs and exits the way it came. Breathe in, breathe out; two steps to complete one breathing cycle.

However, for birds, a complete breathing cycle is four steps, thanks to two sets of air sacs (nine total) found in the bird’s body. Air sacs create a bellows system for the lungs, and here’s what the cycle looks like:

  1. Inhale: Air flows through the nostrils, into the trachea, and fills the posterior air sacs.
  2. Exhale: Air exits the posterior air sacs and flows into the lungs. (In the lungs, the gas exchange takes place, swapping carbon dioxide for fresh oxygen.)
  3. Inhale: Air exits the lungs and flows into the anterior air sacs.
  4. Exhale: Air leaves the air sacs and flows out of the trachea.

What this means is air sacs create a system that gives the lungs a continuous, one-directional airflow. Here, it also flows in one direction through the structures in the lungs called parabronchi, which take the oxygen to the air capillaries. This is where carbon dioxide waste is exchanged for fresh oxygen.

This one-way system lets higher concentrations of oxygen enter the bloodstream. To sustain flight, avian muscles need a high-volume, constant oxygen supply. This breathing system lets them stay aloft, even at high altitudes.

Understanding how birds live and thrive in challenging conditions can make you appreciate your backyard visitors even more. Keep your feeders filled with a high-quality mix of seeds, nuts, and fruit, and enjoy the intricacies of nature. Lyric Fruit & Nut High Energy Mix features a gourmet blend of fruit, seeds, and nuts that attracts orioles, buntings, grosbeaks, and other colorful birds.

The respiratory system in a bird starts at the nostrils, flows through the trachea, posterior air sacs, lungs, and anterior air sacs, all before it cycles out again through the trachea. Dorling Kindersley / iStock / Getty Images Plus