To give an idea of how little oxygen there is where these geese fly, consider that the rule of thumb is a loss of 1 inch of mercury (an outdated unit, I know) for every thousand feet of altitude gained. Obviously this rule of thumb gets less accurate at high altitudes, but it’s not supposed to be perfect. The “standard” sea level pressure is 29.92 inches of mercury, so at 26k feet you’ve lost about 87% of the air pressure, and thus 87% of your oxygen. That’s crazy, this is the kind of altitude that kills humans without supplemental oxygen, and these geese not only survive, they can fly under their own power for quite a while.
Excerpt: Additionally, bar-headed geese hug the terrain as they fly over the Himalayas, taking advantage of the relatively more oxygen-rich air over valleys.
Where did you camp at >26k feet? I was pretty wrecked “sleeping” at 13k feet—mostly tossed and turned the whole night—and then climbing to 15k. Can’t imagine sleeping at 26k!
In my defense of the inaccurate numbers, I calculated it using a rule of thumb I know as a pilot and the numbers are accurate per the rule, and I didn't look at any other tables. To quote myself, "Obviously this rule of thumb gets less accurate at high altitudes, but it’s not supposed to be perfect." In particular, as you go higher, there is less atmosphere pressing down and the decrease gets smaller, so your quoted numbers are likely accurate.
Regarding you spending a night above 26k ft, I guarantee that you were in nearly peak condition, trained for that hike, and spent time at high altitude getting acclimated (or you live at high altitude and were acclimated unconsciously). Even then, most trained hikers at 26k ft can only sustain a walking pace for a length of time. These geese retain enough aerobic power to maintain flight at that altitude. Saying that you were a "bit knackered" the next day is not recognizing how close to the edge your body was- did you measure your oxygen saturation levels and would you care to share them so that everyone can see that you calling yourself a "bit knackered" had you well into the clinical range for hypoxemia, and every doctor in the world would tell you come back down the mountain?
While not everyone will die, the zone above 26k ft is literally called the death zone. The lack of oxygen is like a poison, every body handles a different amount, but 26k ft is certainly high enough to say it "kills humans." People have survived cobra bites as well, but most people agree that cobra venom is lethal.
Is there another 'reason' they fly so high(predator avoidance, optimum energy usage, etc), apart from what the article mentions about the Himalayas shooting up under their migration route?
The same reason why jets fly that high? After all, rarefied air offers less resistance and if there is one thing that birds are adept at it is figuring out how to more efficiently use the air. It would be interesting to see if they only do this when the jetstream is to their advantage or also when it is neutral or even disadvantageous.
The fact that they hug the terrain and go down when they can implies they prefer it lower and only climb that high to clear the mountains. For planes doing 500+ mph air resistance is more of a thing. Then again the jet stream could be handy for them if blowing the right way.
Wow. Presumably they were no where near passing the sound barrier relative to the jet stream, but that is wild. I couldn't find it with my choice of google words, any idea where you found it?
That definitely doesn't ring true, in the conventional sense of the concept of "breaking the sound barrier" which would inflict aerodynamic buffeting on the geese.
There are three or four principles that stand in the way of such an idea.
First, just look at the geese compared to falcons, eagles and hawks. Geese are not classed as serious bird of prey, and don't dive at hundreds of miles an hour to attack their food. They aren't built for that. They run marathons.
Second, watch geese fly, and it's obvious they aren't very fast. Certainly they are not breaking 100 miles an hour regularly.
Third, inside a column of moving air, flying with a good tailwind, they'll catch a bonus to speed. Ground speed. Not air speed. Even if their progress across the ground is drastically improved by riding an air current, and they do well to exploit the natural assist, what they're doing is not "super sonic" in any sense, literal or figurative.
Subsonic speeds at sea level are usually 600 to 700 miles an hour. If their wind current is a moving column of air, there's no way they're going faster than even 300 miles an hour, ground speed. Ground speed, meaning that inside the air current, they're still flying at goose speed, but briskly jogging toward "the front of the train" to maximize apparent speed. So they aren't overcoming aerodynamic drag.
There's no way a goose is flying faster than 200 miles an hour in a hard vertical dive at the ground.
There's no way, even in a dive, that a tail wind is adding more than 400 miles an hour to provide the goose with bonuses that put them near 700 miles an hour.
I think it's because on here it's either expected you are paying for it or know how to get around the paywall. Most of the times it's a case of simply disabling JavaScript.
Because the NYT is a quality newspaper that still does a lot of original journalism and does fact checking. They aren't perfect, but they are much better than most.
Here's a link to the Twitter account of one of the researchers featured in the article [1]. There are a bunch of tweets near the top of that with links to articles about the research that will get you most of what was covered in the Times article.
Just hit the stop button on your browser right after you browse to the article, the payload activates asynchronously so if you stop the page from fully loading, it won't come up.
I wonder if these geese might use some breathing technique similar to what high altitude fighter pilots use above 40 000ft where even 100% oxygen is not enough partial oxygen pressure. Inhaling, then exhaling with resistance. Having experienced overflying migrating geese every year it certainly sounds like they restrict their exhaling with loud guttural sounds.
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[ 3.1 ms ] story [ 69.1 ms ] thread7% effective oxygen(~21% @sea-level).
https://www.the-scientist.com/news-opinion/bar-headed-geese-...
>At 26000ft, the standard barometric pressure is 38 kPa (287 mmHg). This means that there is 38% of the oxygen available at sea level. (from https://baillielab.net/critical_care/air_pressure/)
I camped a night above 26000ft without supplemental oxygen (it packed up) and was ok but definitely a bit knackered the next day.
Regarding you spending a night above 26k ft, I guarantee that you were in nearly peak condition, trained for that hike, and spent time at high altitude getting acclimated (or you live at high altitude and were acclimated unconsciously). Even then, most trained hikers at 26k ft can only sustain a walking pace for a length of time. These geese retain enough aerobic power to maintain flight at that altitude. Saying that you were a "bit knackered" the next day is not recognizing how close to the edge your body was- did you measure your oxygen saturation levels and would you care to share them so that everyone can see that you calling yourself a "bit knackered" had you well into the clinical range for hypoxemia, and every doctor in the world would tell you come back down the mountain?
While not everyone will die, the zone above 26k ft is literally called the death zone. The lack of oxygen is like a poison, every body handles a different amount, but 26k ft is certainly high enough to say it "kills humans." People have survived cobra bites as well, but most people agree that cobra venom is lethal.
i mean ,did they develop some kind of protective mechanism to deal with exposure (not only radiation but UV and all the other stuff thats up there)
May contain some useful clues. That's going to be tough to set up an experiment for.
There are three or four principles that stand in the way of such an idea.
First, just look at the geese compared to falcons, eagles and hawks. Geese are not classed as serious bird of prey, and don't dive at hundreds of miles an hour to attack their food. They aren't built for that. They run marathons.
Second, watch geese fly, and it's obvious they aren't very fast. Certainly they are not breaking 100 miles an hour regularly.
Third, inside a column of moving air, flying with a good tailwind, they'll catch a bonus to speed. Ground speed. Not air speed. Even if their progress across the ground is drastically improved by riding an air current, and they do well to exploit the natural assist, what they're doing is not "super sonic" in any sense, literal or figurative.
Subsonic speeds at sea level are usually 600 to 700 miles an hour. If their wind current is a moving column of air, there's no way they're going faster than even 300 miles an hour, ground speed. Ground speed, meaning that inside the air current, they're still flying at goose speed, but briskly jogging toward "the front of the train" to maximize apparent speed. So they aren't overcoming aerodynamic drag.
There's no way a goose is flying faster than 200 miles an hour in a hard vertical dive at the ground.
There's no way, even in a dive, that a tail wind is adding more than 400 miles an hour to provide the goose with bonuses that put them near 700 miles an hour.
This is plainly wrong information.
https://news.ycombinator.com/item?id=20899356
I love this clip [2].
[1] https://twitter.com/Astro_Jessica
[2] https://www.youtube.com/watch?v=hTLLGv5CfUo