
High-flying geese are ‘the astronauts of the bird world’ - dnetesn
https://www.nytimes.com/2019/09/03/science/bar-headed-geese-oxygen.html
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parsimo2010
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that the rule of thumb is a loss of 1 inch of mercury (an outdated unit, I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.

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tim333
I think your numbers are a bit off

>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/](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.

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parsimo2010
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.

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GnarfGnarf
Why does HN link to so many pay-walled NY Times articles?

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tasty_freeze
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.

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chachachoney
The NYT enjoys a significant brand aura which blinds many to the significant
editorial and journalistic misconduct commited by the organization.

~~~
tasty_freeze
> They aren't perfect, but they are much better than most.

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oh_sigh
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?

~~~
jacquesm
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.

~~~
tim333
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.

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bergesenha
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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tapland
I remember reading about them catching jet streams now and then, a few years
ago approaching super sonic speeds. It's incredible.

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featheredGoose
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.

This is plainly wrong information.

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prpl
See also:

[https://news.ycombinator.com/item?id=20899356](https://news.ycombinator.com/item?id=20899356)

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saargrin
i wonder what do they do about radiation from cosmic ray exposure at that
altitude

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jacquesm
Nothing, they're geese.

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goblin89
GP probably meant potential genetic traits or behaviors that could’ve evolved
to reduce the damage from cosmic rays

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saargrin
right

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)

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jacquesm
[https://www.sciencedaily.com/releases/2014/04/140424223057.h...](https://www.sciencedaily.com/releases/2014/04/140424223057.htm)

May contain some useful clues. That's going to be tough to set up an
experiment for.

