
This Bird Can Stay in Flight for Six Months Straight - danso
http://blogs.smithsonianmag.com/science/2013/10/this-bird-can-stay-in-flight-for-six-months-straight/
======
nether
This is a HUGE outlier among birds capable of long endurance flight, if the
data turn out to be accurate. The Alpine Swift is tiny, 2-ft wingspan and
0.2-lb weight. In contrast, the Albatross stretches its wings to 12 ft and
weighs 20 lb, and can fly for up to a few days straight (longest known
endurance). Similar for the Condor and Stork. The large wingspan minimizes
induced drag and lets it glide extremely efficiently, just like the U-2. As
bird wingspans decrease, flapping frequency increases and flight endurance
decreases, as with pigeons, hummingbirds, and flying insects. Aerodynamically,
flight is vastly less efficient at smaller scales because the air molecules
remain the same size. There are physical justifications for long-endurance
birds being huge, just as there are with long-endurance aircraft.

Data collection seems highly suspect. Collecting v_dot every 4 minutes seems
insufficient for takeoffs/landings that probably take a few seconds. I wonder
if this polling rate satisfies the Nyquist criterion for typical acceleration
changes of the bird? Then they mention relying on the pitch angle to determine
flight. How clear is this correlation? Birds attain pos/neg pitch in climbs
and dives. They adjust their pitch on the ground as they walk, while picking
up bits to build nests, and ducking down to feed their young. I look forward
to seeing this undergo peer review as alphakappa mentions. This type of flight
seems very unusual, but perhaps they manage to feed off insects enough to
sustain themselves.

~~~
interstitial
Since I know practically nothing of birds in depth, how do they sleep during
these extended flights? Or is bird "sleep" something different?

~~~
Someone
[http://en.wikipedia.org/wiki/Sleep_(non-
human)#Birds](http://en.wikipedia.org/wiki/Sleep_\(non-human\)#Birds):

 _" A peculiarity that birds share with aquatic mammals, and possibly also
with certain species of lizards (opinions differ about that last point), is
the ability for unihemispheric sleep. That is the ability to sleep with one
cerebral hemisphere at a time, while the other hemisphere is awake"_

In other words: the brain has two CPUs, and they switch off only one at a
time.

~~~
lostlogin
Early M7 variant? I'd sure like the creator to chime in and dismiss the work
as a marketing gimmick.

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samatman
I almost hesitate to say it, but I did read the article hoping to find the
average airspeed velocity of a slightly-laden European-African swift. I feel
as though the BBC would have included this important information.

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cadab
From the study[1] here is an image[2] of the comparison between flying,
gliding and resting.

[1][http://www.nature.com/ncomms/2013/131008/ncomms3554/full/nco...](http://www.nature.com/ncomms/2013/131008/ncomms3554/full/ncomms3554.html)
[2][http://www.nature.com/ncomms/2013/131008/ncomms3554/carousel...](http://www.nature.com/ncomms/2013/131008/ncomms3554/carousel/ncomms3554-f6.jpg)

Edit. Its a shame there no technical details of the sensor, I'd be interested
in seeing how a device like this kept functioning over a year.

~~~
unwind
It only takes ones reading every four minutes, which probably pushes the duty
cycle for the processor and sensor chips down enough to make the energy
budget.

Assuming a slow 3 seconds for each cycle of "wake up, initialize sensor, take
a reading, store it to flash, set timer, go to sleep", that's a duty cycle of
1.3% which is pretty nice.

~~~
swamp40
> "wake up, initialize sensor, take a reading, store it to flash, set timer,
> go to sleep"

Actually, you can do all that in about 30ms.

Less, if you just save to RAM and then only write to flash when you have
filled up your buffer.

~~~
pscsbs
Scientists generally don't want their data stored in volatile memory. If
something goes wrong, they lose valuable data points.

~~~
swamp40
You can't typically write just 1 byte into flash - you have to write in
_pages_ of say 4KB.

And writing to flash is painfully _slow_.

So it's most efficient (current-wise) to store up 4KB worth of data in RAM and
then write it all to flash in one fell swoop.

It's a tradeoff with data security, but I think it's a good tradeoff because
only rarely will things go wrong, but the additional current burn is
guaranteed and constant if you write every datapoint to flash.

Magnetic FRAM is making a comeback just to scratch some of these low-power
itches. It's faster, uses less power, and has greater write endurance. TI even
put it in one of their latest MSP430's.

------
alphakappa
(Note, this is just a critique, not criticism of some obviously painstaking
research)

It would be good to see the results after these experiments get peer-reviewed
and replicated. Without just the information presented, it's possible to
imagine issues. For example, data is collected every four minutes (We don't
know for how long, but let's assume that it's for a few seconds to conserve
power). Is it possible that when they are on the ground, they aren't
completely still - will their motion on the ground be mischaracterized as
flight?

It would be great if an altitude sensor could be practically added to the
sensor package.

~~~
deltaqueue
My first thought would be to scoff at your criticism. Would the birds' travel
patterns be any less impressive if they were resting for very short periods
during these 200 days? The sensor measures acceleration, so the only potential
confusion might be with light movement near ground / trees.

But according to another study, some migratory birds rest for only seconds at
a time during their flights:

[http://www.livescience.com/1045-migrating-birds-hundreds-
dai...](http://www.livescience.com/1045-migrating-birds-hundreds-daily-
powernaps.html)

At 4-minute intervals over 200 days, you have 72,000 datapoints. There are
1,920,000 9-second intervals (avg nap period from other article) over 200
days, so given their data collection spans only 3.75% of this time there's a
chance they missed one of these naps.

Nevertheless, this is still very interesting.

~~~
azernik
That got me curious, so I ran the numbers on the chances they'd miss _all_ of
the naps; assuming these birds take only one 9-second nap a week (28 naps
total over 200 days) there's a 35% chance the researchers would have missed
all of them ((1 - (28 / 1920000)) ^ 72,000), which is pretty reasonable. But
that chance goes down to 8% for one nap every 3 days, and to 0.055% for one
nap a day. I'd say maybe one 9-second nap every few days is the lower limit of
what I'd find plausible (assuming this was run for only one bird).

EDIT: Ah, missed this in the article - they were three birds. So the chances
they'd miss all naps for all three birds goes down to 0.055% for one nap every
three days, and 4% for once a week. So 9 seconds once a week is barely
believable, but if they can reproduce this with another couple of birds that
becomes really unlikely.

------
205guy
Like others, the tech is really promising, and it would be useful to have more
info.

I also think it's fascinating how the advanced tech is allowing scientists to
gain more insight into the animal behaviors that are all around us, yet still
unknown.

Another migratory bird feat is the Pacific golden plover[1] that fly from
Alaska and Siberia to Hawaii and New Zealand over several days. The incredible
thing is that after raising their young in the north, the parents fly south
without them. The young birds fly south by themselves and find the islands by
themselves (presumably). There is much unkown about this migration, and these
sensors would be very helpful.

[1]
[http://www.kilaueapoint.org/education/naturefocus/hnf3/index...](http://www.kilaueapoint.org/education/naturefocus/hnf3/index.html)

------
antsar
Worth noting:

 _The tags only collect data every four minutes, so it’s impossible to rule
out the chance that they touched down occasionally in between these
intervals—but every single one of the data points collected for more than six
months in a row indicated that, at the time, they were either actively flying
or at least gliding in the air._

------
Someone
A different species, a different insane record, and different technology, but
also discovered only because of advances in the miniaturization of
electronics: some arctic terns fly 90.000 km in about 9 months
([http://ardea.nou.nu/ardea_show_abstract.php?lang=uk&nr=4099](http://ardea.nou.nu/ardea_show_abstract.php?lang=uk&nr=4099)).

~~~
takluyver
Nice. To convey the scale better: that's the equivalent of flying twice around
the world.

~~~
seszett
Even better, that's not just the _equivalent_ but they actually _do_ fly
around the world - ok, not two straight flights around the world, but from the
Arctic to Antarctica and back!

------
wikiburner
Slightly related, but here's a recent article on a "Drone That Can Fly
Continuously For 5 Years". I think this was submitted recently and didn't take
off, but it's pretty interesting:

[http://lasvegas.cbslocal.com/2013/10/07/aerospace-company-
de...](http://lasvegas.cbslocal.com/2013/10/07/aerospace-company-develops-
drone-that-can-fly-continuously-for-5-years/)

------
argumentum
This is awesome .. also ironic that on the #4 and #6 stories on HN right now
are these:

    
    
      *This Bird Can Stay in Flight for Six Months Straight*
    

and

    
    
      *Aerospace Company Develops Drone That Can Fly Continuously For 5 Years*

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ccleve
What's more likely: a bird that can fly for six months straight, or a software
bug that caused the sensor to yield misleading data on what the bird was
actually doing?

~~~
PhasmaFelis
How likely would you say it is for an air-breathing mammal to spend its entire
life in the ocean? It would need to be swimming all the time, even while it
slept, to avoid drowning.

------
Ellipsis753
Awesome article and very interesting. However to go on a bit of a tangent what
did people think of the sensor in the photo? It's interesting that such as
small sensor still has long pads for connecting (presumably to program it and
get data off) and also that it has a little tag on the left of the picture
(making it bigger). I can't see a battery in the photo. Is it on the backside
or is it powered in some other way? Also what is the little metal wire for? I
would think that it was an antenna, however they state that they had to find
the birds again to get the data back so it would seem that they don't
communicate wireless. Could it be getting powered from radio waves instead?
What do you think? Is there more information on it somewhere?

------
cjensen
The interesting thing to me is why? What would cause this evolution? Most
swifts fly all day and can barely perch, but they do perch for the night since
they require sight to locate aerial insects and the effort of flying all night
is a big energy drain on a small bird.

I can think of only two possibilities: First possibility is that insects are
dense enough that they are feeding themselves at night. Second is that the
safety of being off the ground plus abundant daytime food makes this a better
survival strategy.

Can't wait to see what the ornithologists come up with to explain this.

------
piokuc
Watch migration of eagle Arnold from Slovakia to (probably) South Africa, on a
google map:
[http://spravatanap.sk/web/index.php/component/content/articl...](http://spravatanap.sk/web/index.php/component/content/article/2-uncategorised/140-lety-
arnolda) The page is in Slovakian but Google translate does a good job.

------
davorak
Article at nature website:
[http://www.nature.com/ncomms/2013/131008/ncomms3554/full/nco...](http://www.nature.com/ncomms/2013/131008/ncomms3554/full/ncomms3554.html)

Scroll through the figures here:
[http://www.nature.com/ncomms/2013/131008/ncomms3554/fig_tab/...](http://www.nature.com/ncomms/2013/131008/ncomms3554/fig_tab/ncomms3554_ft.html)

I could not find the raw data at a glance or the elevation over time which
would have been useful to see if there were any likely points where it could
have landed and taken off again between data points.

------
texasCoder
From the linked wiki article describing sleep in non-humans:

[http://en.wikipedia.org/wiki/Sleep_%28non-
human%29#Sleep%20d...](http://en.wikipedia.org/wiki/Sleep_%28non-
human%29#Sleep%20duration)

Comparative average sleep periods for various mammals (in captivity) over 24
hours

    
    
        Horses – 2.9 hours
        Elephants – 3+ hours
        Cows – 4.0 hours
        Giraffes – 4.5 hours
        Humans – 8.0 hours
    
    

Glad the avg sleep period of humans in captivity has been measured...

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forgottenpaswrd
Great animals. It is spectacular seeing them flying in big groups. They are
also very useful for controlling mosquitoes.

------
GuerraEarth
Since the birds can sleep with just one cerebral hemisphere dormant at a time,
rest while gliding, eat and drink while airborne--and it is much safer in the
air than on land, it actually makes more sense for the birds to remain aloft.
It's just different than what we (can)do.

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goblin89
A sceptic in me suggests that new sensors could exhibit some sort of
unexpected behavior that skewed experiment results.

> Perhaps most exciting is the fact that this finding came after just the
> first time the new, ultra-lightweight movement sensor was used in avian
> research.

------
X4
Swift Rescue: Saving a Protected Alpine Swift, Stuck Atop a Six-Story Building
(HD) –
[http://www.youtube.com/watch?v=T83EHM_rUlw](http://www.youtube.com/watch?v=T83EHM_rUlw)

------
tocomment
I feel like this wouldn't jibe with conservation of energy. Unless the bird
can eat in the air somehow.

It just physically couldn't store enough fuel to fly to fix months straight,
right?

~~~
dllthomas
_" Unless the bird can eat in the air somehow."_

By, say, catching airborne insects. Which is how swifts (and also swallows)
typically feed themselves.

------
elwell
Psh, any bird can stay in flight for 5 years if aboard this drone:
[https://news.ycombinator.com/item?id=6528598](https://news.ycombinator.com/item?id=6528598).

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mikektung
Seems like this would make for a great model for long endurance UAVs

~~~
tfgg
Make the UAVs refuel by eating insects in the air?

~~~
netcan
Don't be silly. UAVs eat micro-USVs.

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moron4hire
"For more than 200 straight days straight"

as opposed to 200 straight days on the sauce?

