Paraglider and hang glider pilots can also soar for hundreds of miles without power or flapping. Soaring birds like condors, turkey vultures, hawks, etc. use the same technique of turning in tight circles in rising air to increase altitude. Once cloud base is reached and the rising air stops, they glide significant distances to the next hillside with rising air. Whenever you see birds in the sky circling around the same spot together, it's because they're in rising air and using it to stay aloft.
“He spent a lot of time flying. He learnt to communicate with birds and discovered that their conversation was fantastically boring. It was all to do with wind speed, wing spans, power-to-weight ratios and a fair bit about berries. Unfortunately, he discovered, once you have learnt birdspeak you quickly come to realize that the air is full of it the whole time, just inane bird chatter. There is no getting away from it.”
― Douglas Adams, Life, the Universe and Everything
I suspect most bird chatter is about sex, not flying.
Like when you're out in the summer evening, and the crickets are chirping and the frogs are croaking, and you realise it's just a whole bunch of males shouting "hey baby, over here!"
I got a bird feeder a little while ago. After watching them closer that I had in the past, I realized something. All that chirping going on either means "Have sex with me" or "Go away, this is mine."
All the chirping I had ever heard basically means the same thing as most of what my peers were saying in junior high.
> It was all to do with wind speed, wing spans, power-to-weight ratios and a fair bit about berries.
As much as I like Douglas Aadms, this statement is just wrong. A lot of bird chatter is songs to demarcate territory, threat warnings, contact calls to maintain flock awareness, young birds saying 'feed me', and others.
I know when a cat has entered my garden by the clucking warning calls that the blackbirds make. They make a different warning noise when I interrupt them on my bird feeder. Sometimes I'm alerted to a buzzard by the calls of rooks who are ganging up on it.
You might have preferred his description of Kakapo-speak in Last Chance to See then
> “The booming [mating call] is deep, very deep, just on the threshold of what you can actually hear and what you can feel. This means that it carries for very great distances, but that you can’t tell where it’s coming from. If you’re familiar with certain types of stereo setups, you’ll know that you can get an additional speaker called a sub-woofer which carries only the bass frequencies and which you can, in theory, stick anywhere in the room, even behind the sofa. The principle is the same: you can’t tell where the bass sound is coming from.
> The female kakapo can’t tell where the booming is coming from either, which is something of a shortcoming in a mating call. “Come and get me!” “Where are you?” “Come and get me!” “Where the hell are you?” “Come and get me!” “Look, do you want me to come or not?” “Come and get me!” “Oh, for heaven’s sake.” “Come and get me!” “Go and stuff yourself” is roughly how it would go in human terms.”
(I once emailed Adams asking when this book would be published in paperback, this was back when the Internet was small enough that one could sleuth and guess nearly anything. He responded three years later, saying that Random House had published it with "the worst cover I've seen in my career.")
Yeah, true. But I've seen three bird calls that don't fit that pattern in my garden. Long tail tits seem to move around in small flocks, probably eating the insects in my trees. Every few seconds one of the flock flies to another tree. If the others don't follow, it flies back. While this is happening there is a constant chorus of little chirps. My guess is that they feel "attracted" to the centroid of the chirps, as a simple, almost mechanical way to keep the flock together (its hard to see each other amongst all the branches).
The other case is juvenile magpies. As adults I mostly hear them shouting aggressively at each other. But if the youngsters don't know I'm there, I've sometimes heard them chatting. The sounds they make are complex and quiet. A bit like this https://www.youtube.com/watch?v=8P4ZVgjslVQ but I've always seen them in pairs or groups when doing this.
Third is the Robin (European). They also have a whisper song. Sometimes they do it so quietly that I have to be within a few feet to hear it. And there's no other bird around. I guess it's a male who is just working on new material to impress the ladies with later.
I recently had a finch(i think) nest underneath my window AC unit and one of the parents caught a cold for about one week. I heard more calls from that specific bird throughout the time, it was much squeakier while making what sounded like normal calls. It made me think that they relay info on frequencies that our ears dont tune into. Just a hypothesis, but was interesting to hear more inbetween sounds that the other birds didn't make. Could also just be a sort of mask for birds, a call that says 'hey Im sick stay away.' Although I think it'd be obvious for them from the change of voice.
Overall it was interesting to listen to them communicate with their young ones. The nest is constantly chirping unless they get warning calls then it gets super quiet until their folks let them know danger has passed.
It was unfortunate when I had to replace the unit, at least I waited for the young ones to start flying. My new unit is half the size and they disliked the new roof I tried building to mimic the size of the old one. I wish them luck. Tough little fellars.
There's thermals (a spot on the land that is warmer than the surroundings so the air rises there), and there's topography that causes rising air (for example when the wind blows at a face of a hill - the air has no choice but to go up).
RC gliders can stay in air basically forever flying back and forth in rising air along a hillside. It's called slope-soaring and it's great fun.
That is dynamic soaring [1] which is I guess a subset of slope soaring, and is pretty rare and nuts. It generally requires flying in the lee of a slope rather than in front of it.
Regular slope soaring is relatively more sedate, fun and accessible if you have the right slope.
Gotta love the end of the video aha! But the whole video is very interesting. As a kayaker myself I can definitely “feel” the phenomenon they are talking about of extracting energy by alternating on two sides of a flow gradient.
That is very interesting. I always assumed sea birds used combination of wing in ground effect [1] and the lift of wind hitting the front of waves to cover long distance, but this explanation makes much more sense for birds crossing oceans.
> RC gliders can stay in air basically forever flying back and forth in rising air along a hillside. It's called slope-soaring and it's great fun.
This was my thought also. The Andes Mountain Range are rather mountain range right next to the ocean. I would think that is a pretty ideal place for a bird to slope soar for a long distance.
Neal Stephenson's Seveneves has a part (part 3) of the book that is set in the distant future. One plot point there is some kind of advanced glider basically exploiting the atmosphere to pick up enough energy over the course of a day to eventually get enough mass (by picking up water) and energy to eventually travel at high speeds & altitudes half way across the planet. Science fiction of course but he has a way of making this somewhat plausible.
Gliders sometimes use water ballast to store more energy so they can stay up longer. Basically after getting towed to an initial altitude they use thermals and ridge soaring to gain altitude. After that it's all about converting altitude to speed and distance based on their glide ratio. Having a high mass apparently helps. Hopping from one lift producing area to another, you can cover great distances.
Currently this is pretty much a recreational activity because you are dependent on weather, sunlight, and other things that are hard to predict and detect. But kind of intriguing notion what you could do if you had a way to reliably find areas with good lift.
On a related note, here's a youtube channel of a glider pilot in Kansas that regularly posts awesome footage from his glider. Here's some awesome footage of him exploring some mountains and exploiting available lift from winds hitting the rocks: https://www.youtube.com/watch?v=Bcd5Z46RGRU
The point about water ballast is actually not entirely accurate - it's not to stay up longer, it's to increase speed. Gliders have a certain angle of attack at which they fly most efficiently (optimal glide angle, i.e. trading the least height for every meter forward). If you add water ballast, the speed corresponding to that angle of attack is increased. The downside is that your downward speed also increases - so when the weather gets difficult or thermals get weak, pilots dump the water.
> The downside is that your downward speed also increases
You're saying the down component of the velocity vector also increases with the velocity itself. Not that heavier objects fall faster, which we know to be untrue from Galileo's famous experiment. I think you understand that, but I thought I'd clarify it.
No you're wrong. Galileo's experiment doesn't apply here. Heavier objects DO fall faster at terminal velocity. A glider in sustained flight is an example of that.
Galileo just showed that objects accelerate at the same rate due to gravity. But they do NOT fall at the same rate unless in a vacuum.
If you want to play about with gliders yourself the sim Condor Soaring is pretty awesome and has VR support. It's a much more chill and relaxing experience than flying combat sims all the time and more engaging than most non-combat sims.
The rising air doesn't actually stop at cloud base, but it becomes very hard to orient because you don't see the horizon anymore. The thermals can also be generated by many different landscape features - they can be triggered by hills (which can also help them release) but there are plenty on flat landscape as well. Also other sources of upward air currents can be used for soaring, e.g. wind deflecting upwards over a hill or waves high in the atmosphere (search "wave soaring" on youtube). There is even https://perlanproject.org/ aiming to do this at 30km altitude.
The other reason gliders stop at the cloud base is that it's illegal to fly close to the clouds in most airspace. Because it makes it very hard to avoid collisions.
Good point. I oversimplified. Birds and pilots tend to not fly up into clouds for visibility reasons but the air keeps rising into the cloud. From experience, it's a surreal experience riding a thermal up into a cloud in a paraglider. Just not safe or legal in most places to stay in the cloud.
Paragliders and hang gliders are still easily beaten by sailplanes. World's record for a single day sailplane flight is 3000km (1800mi), that's been performed on mountain lee waves.
I pass a couple bald eagle nests commuting by bike along the river in Minneapolis. I'm always surprised when I see the eagles flapping their wings, since most of the time they are soaring.
Exactly. The condor (or paragliders) can fly that way only in the Andes, because only there it is possible. Over the Amazon for sure not. It's not the bird, it's the environment.
It definitely works the other way, too. When the thermals are weak the vultures in Himalaya, wait until the gliders are climbing and only then go join them.
Those gliders with huge wingspans and no awkward propeller on the nose look incredibly elegant. There's a gliderport not too far from me and I've always wanted to give flying one a stab. But it's really hard (and nerve wracking, lol!) to conceptualize how they stay in the air using thermals. Especially in staying in control when coming in for a landing.
As others have said, go try it out with an experienced pilot/instructor! It's very accessible.
You might be more comfortable in a motor glider - they have enough thrust to conduct their own takeoff and get you out of trouble but are still light enough to glide effectively.
I think you should just go for it - many gliding clubs have introductory or passenger flight options. I flew gliders for a few years and it's really wonderful - it's very quiet and the view is fantastic. Landing is suprisingly easy most of the time - when people fly "cross-country" (long distances, away from airfields) it's actually common procedure to "land out". Which is basically the same as an emergency landing (e.g. in a farmer's field) but much less stressful because gliders are actually designed to fly well without a functioning engine.
From what I understand, most glider clubs are always looking for new members. Maintenance of the winch, gliders and landing strip is expensive and more members means sharing the costs. One in my province has "introduction days" where you can sit in a two-person glider, in front of an instructor, for a small price or even free.
Owls can fly almost in total silence, peregrine falcons can hit close to 250 mph, eagles can spot a tiny mouse from tens of thousands of feet...
Mother nature is wonderful and terrifying at the same time. Suddenly I am feeling sad for sitting in front of a screen for 8-10 hours a day instead of being out and enjoying what nature has to offer :(
I once stepped out on to a top floor balcony around 1 AM only to be scared witless by an apparition, six feet wide, silently floating up towards the roof.
Fight of the condor: Peru bull fiestas threaten future of rare Andean bird
At a raucous mountain festival high in the Peruvian Andes, a brass band and booming loudspeaker herald the arrival of the most eagerly awaited spectacle.
With the wings of an angel and the horns of a devil, the tonne of life that flaps and bucks and charges into the bullring at first resembles a strange mythological beast.
Snorting and kicking up dust, the hybrid – a raging bull with a condor strapped to its back – strikes awe in a watching crowd as it thunders into the arena, then excitement as it repeatedly attempts to gore a matador. The closer the enraged beast comes to a lethal connection, the louder the cheers of "Olé!"
I remember a story from the early 1980's about Steve Jobs.
Steve asked, what is the most efficient animal in motion?
People would give many answers.
The correct answer was a condor in flight.
A common wrong answer was a human being.
Steve then pointed out that the human isn't even close. Not even in the running as far as efficiency of some other animals.
But . . . if you give the human a bicycle, then the human absolutely cleans up in terms of efficiency. Steve wanted personal computers to be "a bicycle for the mind".
Calling Al Bowers "a NASA scientist" is like calling Jeff Bezos "some rich guy". Al was (now retired) the Chief scientist at Armstrong Flight Research Center, and has been a huge inspiration to hundreds (maybe thousands) of young interns over the years.
I know him personally and he certainly wouldn't. He's one of the most humble people I've ever met. I just wanted to emphasize that he's not just any NASA scientist.
That was really interesting, thanks. For the pilots of HN out there, it's an interesting discussion about adverse yaw and why birds don't suffer from it, and what we can learn from them.
Bird physics are really interesting. There's an excellent (and accessible) book called "The Simple Science of Flight" by Henk Tennekes (who is an expert in the study of turbulence) which I really enjoyed reading, highly recommend it.
Andean Condors in Peru glide from 14'000 ft up in the andes of Pampa Galeras all way the down to sea level at the Guano islands in the coast of Paracas. All to get stuffed eating crushed sea lions babies carcases..
After eating , Condors can't take of from the ground by flapping.. they got to "hop" up a hill to be able to launch into the incoming air to get some altitude.
Then they fly back up to 14'000ft by a combination of dynamic lift, thermals and wave induced lift when available.
A few years ago, a group of top paraglider pilots tried to recreate their journey up the mountains, but it ended with both pilots pretty badly injured after encountering nasty turbulent winds on the mountain canyons.
The article says more than 100 miles, that's 1 significant figure, and likely somewhere in the 100-120 mile range. More than 160km is the appropriate conversion, and indeed what the article says, it's likely 160-200km.
If I say it's 50km to somewhere, an appropriate conversion would be 30 miles, not 31.07 miles.
Fossil evidence shows records of some truly enormous flying beasts. One of the topics of the video is how their existing relatives, the condors, make use of updrafts and air currents to avoid spending the energy to flap their wings. We're all familiar with the trope of vultures circling above a dying animal, but the circling may also be riding an updraft to maintain altitude without expending additional energy.
The low aspect ratio wings paired with the wing tip feathers to reduce wing tip vortices for birds of prey is pretty cool compared to the super high aspect ratio wings of Albatrosses.
Any land based analogies (that don't involve a geological time scale) are going to be bad because the land doesn't move whereas the air does and efficiently harnessing that movement to get gravitational potential energy which can be converted into motive power is how gliding things stay airborne
The article doesn't link to the original study, but I would be curious to know how long was the next longest flap-less flight. If the first one is 5 hours, and the next is 4.5, awesome, but if the next longest bird was not flapping for only 35 minutes, I would attribute this to equipment malfunction rather than some awesome paragliding bird. Science is fascinating.
Hmm, who is more efficient: the programmer who writes 100 lines then deletes them after finding them all unnecessary, or the programmer who (as implied) doesn't need to write the lines in the first place?
In aviation, by definition gliding is unpowered flight, like coasting in a car. If you're doing performance calculations, there are different equations for gliding and powered flight.
Sadly most of the depiction of 'thopters in Dune media have not been 'thopters but boring generic VTOLs. I think the only place where they actually had real bird-like 'thopters was the Dune RTS games.
> I don't know any aircraft that propel themselves by moving wings.
Well, there are helicopters, of course, and—less common but more what you probably had in mind—ornithopters, both of which using moving—rotary in the first case, flapping in the second—wings.
Unless there is some sort of bone oddity in the joint, the wings are not locked in place. The bird must still self-support via muscles.
Try it. The relatively bird-like way is like a gymnast on a pair of rings, arms horizontal. Doing things upside-down, consider standing with outreached arms holding heavy objects. It'd be half your body weight at the arm midpoints, which due to leverage is roughly like a quarter of body weight in each hand.
Even without any flapping, that is going to consume lots of energy.
This 'relative bird-like way' makes no sense at all. Humans are not birds. They are not even related. They are completely different organisms.
Humans have had zero evolutionary pressure for minimizing energy expenditure while in hovering flight.
Birds had more than 150 million years to optimize their benefits for survival and reproduction [1,2]. They even survived the Cretaceous–Paleogene extinction event [3] where the evolutionary pressure of food scarcity was at an extreme.
The elbow and 'finger' joints are fully extended, so are locked and don't require energy to support. The pectoral muscles are supporting the weight of the bird, but they are very much stronger proportionally than ours.
But it's an interesting question. According to a couple of papers I found online [1][2], when soaring birds are soaring their energy use is not much higher than when sitting. Soaring is very efficient.
The gymnast example is fighting against gravity with absolutely no external factor other than personal strength, but the warm air / wind resistance pushing against the wings that allows the condor to fly for so long without flapping is contributing immensely to their ability to hold the wings in place.
A few of the other comments have covered good reasons why this is a poor analogy. One thing to remember: wing muscles are the most well-developed muscles on birds, while human arms are extremely weak compared to our legs.
A better analogy would be that flapping-wing flight is to soaring how running is to standing (maybe on a moving platform to account for turbulence, etc.).
I have no idea about birds, but I read that horses and other animals can sort-of lock their feet in place and require minimal effort to stay in place -- perhaps birds have such mechanisms as well and it takes very little effort to just glide -- otherwise, they would not do it.
The physics are different. For a gymnast the support is at the hands, so the force felt by the gymnast is a product of his weight and the distance between his shoulders and hand palms. For a bird I'm guessing that air applies support to the body and wings, so forces are more evenly distributed throughout its length.
