Parrots’ muscles need regular oxygen to remain airborne during flight, especially at high altitudes. How avian species sustain respiration during flight once baffled scientists, but no longer.
Science has shed light on how birds breathe when humans experience oxygen saturation. This occurs when the bloodstream’s oxygen-saturated hemoglobin (Hb) falls as a percentage of the total hemoglobin.
We’ll explore queries about the intricacies of the avian respiratory system and examine the gas exchange process. Then, we’ll discuss how parrots breathe so efficiently at high altitudes.
How Parrots Breathe During Flight
Under normal circumstances, parrots don’t breathe through their beaks (open mouths).
Open-Mouthed Breathing
Open-mouth breathing may occur when parrots are unwell or particularly distressed.
If a parrot opens its beak to breathe, it signifies medical or psychological distress. You must remove any stressful stimuli or cease what you do to allow them to calm down.
If no environmental stressors exist, this suggests a medical cause, such as a respiratory problem.
Breathing Through Nares
Under normal circumstances, parrots inhale air through their nares (or ‘nose holes’). These are situated just above (at the base of) the beak of most avian species.
There are exceptions, as the nares in Kiwis are at the tip of the beak. In psittacine species, the nares are covered by a horny structure called the operculum, which protects the nasal cavity.
Air inhaled through the nares passes through the nasal cavity, choana, oropharynx, larynx, and trachea to reach the two mainstem bronchi and the lower respiratory tract. This is where gas exchange occurs.
How Parrots Get Oxygen
Our journey starts at the nares, where the air is inhaled.
This air is warmed, moistened, and filtered in the parrot’s nasal cavities. Then, it’s passed through the choana, oropharynx, larynx, and into the trachea (windpipe).
After a short distance, the trachea bifurcates (splits into two branches). As an interesting aside, at the level of tracheal bifurcation, you’ll find the syrinx (vocal organ) in many avian species, including parrots.
The bifurcation of the trachea results in two main stems or “primary” bronchi, one of which branches towards each lung. The primary bronchi traverse the lungs and empty into the abdominal air sacs.
Within the lungs, each primary bronchus gives rise to secondary bronchi. These further branch into tertiary bronchi (also called ‘parabronchi’). From these tertiary or parabronchi, air capillaries arise.
The lower respiratory system is where gas exchange occurs. Gas exchange refers to oxygen entering the bloodstream and carbon dioxide moving to the airways for exhalation.
Unlike in mammals (where gas exchange occurs at the alveoli of the lungs), in parrots and other birds, the process happens within air capillaries.
Air capillaries can be mentally pictured as tiny air-containing tubes from the tertiary bronchi.
They’re smaller than mammalian alveoli with a thinner blood-gas barrier. This barrier is between the air-containing spaces and the bloodstream, where gas exchange occurs.
The result of this is improved respiratory efficiency compared to mammalian species. Parrots obtain oxygen from inhaled air in their air capillaries.
Oxygen in the air capillaries moves into closely adjacent blood capillaries, and carbon dioxide in their blood capillaries moves into the air capillaries, ready to be exhaled.
How Parrots’ Respiratory Systems Enable Them To Fly
Even at rest, parrots inhale more oxygen than other vertebrates. As if this wasn’t impressive enough, oxygen consumption increases dramatically during flight.
Of course, this means that a very high rate of gas exchange is required to provide a parrot with sufficient oxygen to sustain this phenomenal feat. Parrots have looped airways for directed (one-way) airflows.
Several evolutionary adaptations allow birds to achieve efficient gas exchange.
Birds possess air capillaries rather than alveoli, which results in more effective gas exchange. The lack of alveoli also means less “dead space” within the respiratory system, resulting in more efficient respiration.
Birds also possess several pneumatized bones, which serve the dual purpose of bestowing a lighter skeleton and providing additional air-containing spaces (extensions of the air sacs).
Avian air sacs serve as reservoirs, allowing parrots to maintain continuous unidirectional airflow through the lungs. So, pneumatized bones and air sacs also help enable a parrot to fly.
How Parrots Breathe At High Altitudes
Parrots aren’t high-altitude birds, and almost all parrots are non-migratory. There are only two exceptions: the swift parrot (Lathamus discolor) and the orange-bellied parrot (Neophema chryogaster).
The vast majority of species permanently live in lowland tropical forest environments. Regarding their anatomy and physiology, parrots are built for relatively short bursts of low-altitude flight.
We can’t include parrots with high-altitude birds, such as cranes and condors.
Birds that fly at high altitudes have adapted to the lower oxygen conditions by increasing the amount of hemoglobin (the oxygen-carrying molecule in the blood) each red blood cell contains.
This adaptation is permanent and constant. On the other hand, migrant birds (i.e., those temporarily entering high altitudes) will adapt by producing more red blood cells.
This permits a greater blood oxygen-carrying capacity. However, the downside is thicker blood, elevating the risk of blood clots and strokes.
