I’m reading ‘‘Everest: Mountain Without Mercy,’’ and it contains this sentence:
How does this work? Do they inhale but do not need to exhale? Or do they not even inhale? (And if they didn’t inhale … no, I’m not going to do that joke.) Anyway, please clear up my confusion.
IANAO (ornithologist), but I’m pretty sure that all air-breathing vertebrates have lungs and breathe in and out though their tracheas. Considering how high of metabolisms birds have, I think that any “exhaust port” (sorry, but I don’t know what else to call it) would be obvious.
Look, Pucky (and, het–don’t ever take up horse breeding, OK? 'Cause then you’d be Horse P****, and we wouldn’t want that would we?)
If the bird doesn’t inhale, it chokes to death. (Unlike Clinton, who never chokes, inhaling or not.)
If it doesn’t exhale, it BLOWS UP LIKE A FREAKING BALLOON!
Okay?
Gooood.
From “The Audubon Society Encyclopedia of North American Birds”:
When a bird inhales it takes in air (by inspiration) into the lungs, where the oxygen of the air is picked up by the blood…and carried to the cells of the body. The cells use oxygen in the “burning” (oxydation) of digested food…, a chemical reaction that releases energy (fuel) for the bird’s daaily needs, and in maintaining its high body temperature. Carbon dioxide, one of the waste productsof metabolism, carried by the blood to the lungs, is released from the body and expelled (by expiration) into the outside air when the bird exhales.
[Way lots more stuff on the nostrils, the glottis, the trachea, the syrinx, the lungs, the air sacs. Other interesing points summarized below.]
Breathing rates and control of breathing -
Turkeys and chickens (limited flight birds) - 16-18 breaths per minute (bpm)
Cardinal at rest - 45 bpm
House wren at rest - 80 bpm
Breathing rates are affected by outside temperature (hot vs. cold) and torpidity (hibernation - as with sleeping hummingbirds and nestlings).
Some birds coordinate breathing to the wingbeats (pigeons exhale with downbeat of wings, crows exhale on upbeat of wings). Others do not (one red-tailed hawk beat its wings 13 times without drawing a breath).
Breathing rates of birds are controlled, as in mammals, by a nerve center in the medulla oblongata.
Chemical receptors in the lungs are sensitive to the levels of carbon dioxide inhaled, and can act to increase or decrease the breathing rate.
Nope, nothing on one-way breathing or gills or other escape hatches.
Now the bird may have some adaptation for less oxygen available at higher elevations. (I am not familiar with ‘bar-headed geese’ - got a Latin name available?) I’ll check the rest of the library and periodicals, but it sounds like this sentence seriously slipped by an editor.
Anyone seen colibri lately? This is his department. I’m just learning ornithology.
You never heard of the fart gull? It takes air in the nostrils and, after using it in the lungs expells it with great pressure via an opening just under the tail. This has been shown to provide as much as 40% of the energy needed to maintain flight.
Read this last night in an entertaining book, Why Elephants Have Big Ears – Understanding Patterns of Life on Earth, by some guy named Chris Lavers. Interesting and entertaining, but I am a lawyer and cannot vouch for his science. This was in a chapter concerning the arguments for and against dinosaur hot-bloodedness
What about the respiratory system of dinosaurs? Bakker suggested that this too might have had more in common with birds than with reptiles. Bird lungs consist of a series of paralell tubes through which air flows continuously in the same direction whether the bird is breathing in or out. Air flows not only through the lungs but also through a complex series of air sacs that occupy large areas of the body cavity and even extend into the skeleton. The fact that skeletal air sacs are intimately connected to the respiratory system was demonstrated in 1758 in an unconscionably gruesome experiment by John Hunter,who blocked the windpipes of chickens and hawks and then cut through their wings. He found that the birds could still fill their lungs with air by breathing through their severed wing bones. Bakker noted that thevertebrae of brontosaurs and some carniovorous dinosaurs also contain cavities like those of birds …
Bird respiration is rather complex, and somewhat difficult to describe. But, as they say, a picture is worth a thousand words (or something like that).
For mammals, the trachea essentially terminates with the lungs. So, as one inhales, air passes through the trachea into the lungs, and the lungs fill. Gas exchange occurs, and the “bad” air is then exhaled. Good air in during inhalation, bad air out during exhalation. We all know this.
For birds, the lungs are offset from the trachea. Air passes through the trachea in birds much as it does in mammals: in during inhalation, out during exhalation. However, during inhallation, most of the air goes into a posterior air sac, and some passes through a shunt to the lungs. During exhalation, the air is pumped from the posterior air sac through the lungs. Then, during a second cycle of inhalation, the air from the lungs is passed into an anterior air sac (while, of course, a new batch passes into the posterior sac). During a second cycle of exhalation, the air from the first cycle, which now resides in the anterior air sac, is shunted back into the trachea and out (while the air from the second inhalation passes into the lungs).
So, what this all boils down to is that air is constantly moving through the lungs in one direction, and it takes about two complete cycles for a given batch of air to pass through the system.
Thank you Darwin’s Finch. Someone ‘borrowed’ our copy of both Ornithology, 2nd edition and Manual of Ornithology: Avian Structure & Function (both great books). All I have left are manuals from the 1950s. Thank you for clarifying that.
Thanks, Darwin’s Finch, for that very timely link! I’ve recently started working at an APS Wildlife Rehabilitation facility. Yesterday, I assisted in surgery on a barred owl, and had to “breathe” for her through the anesthesia; a crucial part of surgery on birds. I’m new to this, and asked the vet why, when I let oxygen through the tube, the hind leg rising was the indication of how much to give. Air sacs were explained, but your link really helped me to understand it.
I found this additional page quite helpful: you can get there by clicking from your link, but I think it’s worth note on its own.
Thank ya much.
A rather interesting visual can be found here (which you can also get to via the first “Useful Link” at the end of elelle’s link (which, as noted, can be reached via my previous link). It requires Shockwave to view the animation.
Not to worry.
I don’t like being around horses.
Especially the back half of one.
Which is why you’ll excuse me now …
I consider myself pretty well educated, but I’m really surprised that somehow I’ve never heard of this unusual fact about birds breathing. I knew birds had air sacs, but I didn’t know why.
Thanks for the information about this unique fact!
I don’t approve of it at all, but a friend told me that if you give seagulls Steradent (fizzing denture cleaning tablets), they explode. Is this somehow related to the air-sac busines?
Ross: I suspect that this tale is a variant of the Alka-Seltzer myth, which Cecil discusses here (among other things which supposedly make birds explode). Specifically, he notes:
At any rate, any potential for explosion would be associated more with the digestive system, not the respiratory system.