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Metal-Feathered Macaw Viability Part 2: Best Wing Shape?


I'm designing a macaw that has metal feathers, claws, and a metal beak--to be particular, steel. To start with, assume a regular anatomy/physiology of a macaw+steel feathers, claws, and beak.

The growing beak/claws/feathers are pure steel, all the way through. They have the same shape and structure as regular feathers (barbs, strands, etc.)


Given the increase in weight due to this metal, what physiological/anatomical changes would be required to still permit flight with these modifications? The bird still needs to be able to fly, but I suspect it will not be able to do so for as long as a normal macaw.

By "flight" I mean take off and maneuver under its own power. No pushing it off a cliff or making it "glide" like a flying squirrel. Actual flight.

Don't regard the way the macaw grows the feathers or gets the steel it needs. It just grows them. This is about the aerodynamics.

Please don't write handwavium/it's magic answers or comments. I want to develop this part scientifically and realistically. It's tagged as science-based, not magic.

Thank you to the Sandbox for helping grow this question.

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    $\begingroup$ Note to Downvoters and VTC Casters: Please leave a detailed comment outlining why you are downvoting/VTCing this question and leave a suggestion showing how you think this issue can be fixed. Thank you for being considerate. $\endgroup$ – FoxElemental Jun 17 '18 at 20:32
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    $\begingroup$ It's going to be far simpler to lower your planet's gravity than figuring how to get a metal macaw to be able to take flight. Unless metal = metallic, then you can substitute carbon nanotubes. $\endgroup$ – Ian Kemp Jun 18 '18 at 6:52
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    $\begingroup$ All birds' wings are structured according to their body mass. Just by replacing talons and beak with steel, you'd need stronger neck and leg muscles, and larger wings. Steel wings, even when as thin as regular feathers, would increase so much the weight that the whole body should be changed as to accommodate that new condition, to the point that you wouldn't be having a macaw anymore. Plus, metal wings means that the poor creature's temperature would cook it and surely make it electroconductive so that at the first storm bzzzt! $\endgroup$ – Valerio Pastore Jun 18 '18 at 7:59
  • $\begingroup$ Is it completely robotic or is it an actual macaw with just an outer metallic finish? $\endgroup$ – Hawker65 Jun 18 '18 at 13:27
  • $\begingroup$ @Hawker65 Regular macaw, metal feathers/beak/talons. $\endgroup$ – FoxElemental Jun 18 '18 at 13:39

I'll take a stab at this...

First things first, I'm finding it hard to find exact figures about the weight of a macaw's feathers but a general consensus seems to be the bird itself weighs around 1kg (depending on species, but I assume you want a scarlet or blue and yellow as they are the most famous and both weigh 1kg).

According to this answer on Quora a chicken's feathers account for 3.3% of it's body weight and a feather weighs about 0.0082 grams. Let's assume a macaw's feathers take up a similar portion of it's body weight, this would place it at having approx. 4000 feathers.

This handy site lists the density of both feathers and steel. Feathers being 0.0025 g/cm3 and steel being 7.8 g/cm3, or 3000 times more dense. This would make each steel feather weigh about 24.6g meaning your parrot now weighs 99.4kg give or take, but only if we can directly convert one to the other. But this calculation probably doesn't hold water as the density conversion between feathers and steel is inaccurate due to the different compression of each item. Unfortunately I'm not sure the density for keratin works as I can only find the density for α-keratin and not β-keratin which is what feathers are made of. I'm assuming it's more dense based on the descriptions but can't be sure.
The density of α-keratin is approx. 1.3 g/cm3 which would make each steel feather weigh 0.04 g and the total weight being around 190g. When you factor in Georg Patscheider's comments about the upper bound of 7.8kg this does seem to fit reasonably well and is a lot lighter than expected, so this might work better than I thought.

Still, 200 grams is an extra 20% weight, which is a lot of extra weight for a bird to carry but not outside the realms of possibility. Eagles can be known to carry their own body weight so 20% may be possible for a parrot. Though this isn't including the beak and claws so that might be an issue.

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    $\begingroup$ +1, I was going to say exactly the same thing. Of course it's possible, the answer is rockets. $\endgroup$ – Nacht - Reinstate Monica Jun 18 '18 at 5:47
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    $\begingroup$ I don't think the "3000 times more dense" figure is relevant here. 0.0025 g/cm^3 looks like the density of loose, fluffy feathers with a lot of air between them, while the 7.8 g/cm^3 is the density of a solid block of steel. The density of steel feathers will be much closer to the 0.0025 g/cm^3 figure, purely because feathers are fluffy and have a lot of air between them. The way to do it would probably be to compare the density of steel to that of the material feathers are made of. I'd guess the densities differ by a factor on the order of 10, not 3000. $\endgroup$ – Someone Else 37 Jun 18 '18 at 5:58
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    $\begingroup$ I agree with SomeoneElse. The estimate given of 0.0025g/cm^3 is largely the air in between, while the steel is a solid block. To compare them more accurately, consider that the density of keratin (the stuff feathers are made of) is ~1.33g/cm^3 $\endgroup$ – Dubukay Jun 18 '18 at 8:07
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    $\begingroup$ The math still does not work out. Think about it this way: if a whole macaw weights 1 kg and has the average density of water (1 g/cm^3, which should be close given that it consists of about 80% water), if the whole bird were made out of steel (7.8 g/cm^3), it would weigh 7.8 kg. So 7.8 kg is an upper limit. $\endgroup$ – Georg Patscheider Jun 18 '18 at 10:27
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    $\begingroup$ real issue is steel feathers will be too weak to retain their proper shape making flight impossible. $\endgroup$ – John Jun 27 '18 at 13:46

If it's pure steel? Hell nah. But there are other options. The scaly-foot gastropod, also known by the considerably more badass-sounding names of iron snail and Chrysomallon squamiferum, hails from the deep-sea thermal vents known as black smokers, deep-sea vents from which water gushes constantly. That water, by the way, originates from below the mantle.

The SFG uses the chemosynthetic bacteria lurking in its glands to absorb and mineralize poisonous iron-sulphides in the water, making them non-poisonous for the snail. It then coats its shell with the minerals, constructing an unique three-layer structure. The outer layer, used to block the bulk of the attack, is made up of greigite (Fe3S4), a ridiculously hard mineral. Then comes a middle layer of squishy organic matter purposed to absorb the shock of impacts, dents and blows. Finally, an inner layer of aragonite (CaCO3), designed to prevent asshole crabs from sticking their nasty claws into the shell and picking it apart splinter by splinter.

This armor is so much better than anything which we possess, including Chobham Armor, that the U.S. Army is actively conducting research about it with the hope of developing new next-generation armor using the same build. By the way, take a look at it. enter image description here enter image description here

Those are metallic scales made out of iron minerals. Iron minerals that are poisonous and magnetic. The scales are there because of the tooth-harpoon-hurling killer snails. Namely, they serve to deflect the harpoons entirely. And they can also shrug off diamond-tipped indenter heads. An industrial-grade diamond applied with the pressure of several metric tonnes. Colossus of the X-Men's mutation doesn't seem so far-fetched any more, does it?

Oh, and they don’t really eat anything, relying on their chemosynthetic bacteria for sustenance instead. In layman’s terms, that means that the snail keeps itself running by oxidating the sulphides in the water, all of which are lethally poisonous to most lifeforms, including the snail itself. The only reason it survives is that the bacteria chemosynthetize the sulphides, enabling the snail to quite literally live off of the poison.

So, if you want your metal-feathered macaw, while pure steel's completely impossible (on account of it being a biological organism and all), you could hypothetically simply splice its genes with the SFG, grant it a symbiotic relationship with the same chemosynthetic bacteria, and thus have greigite nanoscale armor integrated into its beak, claws and feather in the same way. And relative to its weight, this is the strongest organic nanomaterial yet known to man. Can't find any figures on the density in g/cm3 of the SFG's iron plate-mail scale armor, but could it be light enough for your metal macaw to get off the ground and fly? Maybe...

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    $\begingroup$ Upvoted purely for cool snail. $\endgroup$ – Ian Kemp Jun 18 '18 at 6:52
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    $\begingroup$ I’ve actually gotta nitpick- the water from black smokers usually originated from water pulled through cracks in the surface via normal convection mechanics, and isn’t pulled up from the mantle. There’s a good diagram on the Wikipedia page for MORs: en.m.wikipedia.org/wiki/Mid-ocean_ridge#/media/… $\endgroup$ – Dubukay Jun 18 '18 at 8:12

Power to weight ratios

There are four forces at play for any airborne object: Lift, gravity, thrust and drag. We'll focus on drag and lift since those are the hard parts.

Assuming Adalia's math is right (may be a bit high but let's go with it) and this steel macaw now weights ~100kg, then the wings must generate sufficient lift to overcome that ~100kg of weight. The lift equation tells us what we need to know:

$$L = C_l \frac{r \cdot V^2}{2} \cdot A$$

where $L$ = Force of Lift, $C_l$ is the coefficient of lift, $r$ is air density, $V^2$ is velocity squared and $A$ is wing area.

For our purposes, the wing area, air density, lift coefficient all remain unchanged from a regular macaw. So, in order to support a 100kg parrot in flight, we need to go 10x faster (since velocity is squared in the lift equation).

What a drag

Drag kills. The equation for drag is as follows:

$$D = C_d \cdot \frac{\rho \cdot V^2}{2} \cdot A$$

Where $D$ is the force of drag, $C_d$ the drag coefficient, $\rho$ is air density, $V^2$ is velocity squared and $A$ is frontal area. For our macaw, drag coefficient, air density and area remain unchanged. We only have velocity to work with.

From our lift equation, we know that we have to go 10x faster to support our steel macaw. How unfortunately that means that the macaw must expend 10x the energy to get up to speed and to just stay in the air. Low speed flight will be especially energy intensive since lift will have to be generated from forcing air downward (a la helicopter) instead of suction upwards (a la airplanes).

Further, the wing loading on this bird will be absurdly bad. Maneuverability will be atrocious since the high wing loading demands that all or almost all lift is spent keeping the bird in the air; leaving little to nothing left for turning.

Landing is going to be tricky too. When a bird comes in to land it has to slow down from whatever it's flight speed is to zero. This steel macaw is going to have a really hard time with this since it's wings generate pathetically small drag compared to its massive weight. All landings will be crash landings since the air sure isn't going to help slow the bird down. Oh no, that job belongs to Mr. Dirt-in-your-beak.

We need more power

In order to make this macaw fly, you'll have to upgrade his little fleshy heart and muscles to steel or handwavium. I don't know of a mechanism that will generate the power required to keep this steel weight in the air and still fit in the size of a big bird. Keeping that bird fueled for any substantial flight will be really tough since the flight performance is already so bad.

This bird is grounded!!!

...without serious handwaving. Anyone who knows anything about aerodynamics will have exceptional difficulty with suspension of disbelief.


A helpful mental image for why this is such a bad idea: Take a steel plate from an Olympic lifting gym. Try to get it to fly. How fast is it going to have to be flying to stay in the air?

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    $\begingroup$ Hey, it turns out my original weight calculations were way way off, so you may want to change your calculations too. $\endgroup$ – adaliabooks Jun 18 '18 at 12:45
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    $\begingroup$ The lift and drag formulas apply to fixed wings. Bird wings change shape and function very differently from plane wings. I think it would be more relevant to calculate the lift that has to be generated by one wing flap to compensate gravity. $\endgroup$ – Hawker65 Jun 18 '18 at 14:03
  • $\begingroup$ @Hawker65 I get where you're going with that but the project is so ill advised to begin with that the extra calculations required for flapping wings just aren't worth it. $\endgroup$ – Green Jun 18 '18 at 17:26
  • $\begingroup$ can we also vary "r", a denser atmosphere could help. $\endgroup$ – James K Jun 18 '18 at 18:46
  • $\begingroup$ Personally, I like to give a direction but I'll leave the calculations to OP if he really wants to make this realistic. $\endgroup$ – Hawker65 Jun 19 '18 at 10:56

This answer has been edited to account for a change in Adalia's answer

Your problem is wing loading.

Flight is magical, but it's not irrational. Without thrust (airplanes, rockets) a bird must balance its weight with the carrying load of the wings. How much the wings are loaded will affect balance, agility, ease of landing and takeoff, etc.

The upper limit for birds is about 5#/sqft. If Adalia's right (and I have no reason whatsoever to doubt him), then your 1.2Kg (2.65#) bird would require about 0.53 sqft of wing or .265sqft per wing (4" wide, 1' long...).

This is well within the capacity of a bird to fly. The only real issue is the necessity for flexibility (steel generally isnt, even as thin as this is if we want it to not bend and break apart like an electrical knock-out) and a cohesiveness between "feathers" that might not exist with steel (but at this level of fineness, it might).

So, I'm going with yes, the bird can fly, but you need to either handwave the flexibility of the steel or you need to come up with an alloy that allows the flexibility without generating heat or breakage.

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  • $\begingroup$ @adaliabooks Did you change your steel weight calculations? It appears you only changed your keratin calculations. $\endgroup$ – JBH Jun 18 '18 at 14:00
  • $\begingroup$ yeah, I've edit the answer again to make it clearer. The first steel weight calculation was wrong due to some flaws in my assumptions. $\endgroup$ – adaliabooks Jun 18 '18 at 19:57
  • $\begingroup$ @adaliabooks, Thanks! I've updated my answer. $\endgroup$ – JBH Jun 19 '18 at 1:04

It depends on what kind of metal those feathers are made of. If you assume that it's Iron or steel, of course it would be far too heavy.

But since it's a fictional history you can dig deeper onto the fictional side so here is a solution:


adaptations: You did ask what kind of adaptations would be necessary to allow a metal feathered macaw to fly, I could think in only one logical way:

Organic alloy

It doesn't need to be pure metal to be a metal alloy, lets work on that! What we tend to mix with Iron to turn it more light and stronger? Carbon! But wait! That's just steel, still isn't light enough...

Carbon based lifeforms tend to be good at, well, manipulating carbon at molecular level, a bird put on right evolutionary pressures, could evolve the right biological ways to produce Carbon Nanotubes. Carbon nanotubes have the reputation to be the strongest and stiffest material discovered since and its as light as, well carbon, if you ever held a piece of graphite you know what I'm talking about.

And since Iron is contained on blood, and we know that there is no trouble in mixing carbon with iron (Humanity does it all the time!) yeah that is...

Your macaw have feathers made of a crystalline lattice or intricate net of Carbon Nanotubes mixed with iron in a fictional organic alloy developed by a species of macaw which lived on a surprisingly specific fictional conditions to evolve extreme fight adaptations, maybe to resist an acid or corrosive enviroment or whatever, those details doesn't matter much to the history (I suppose).

I hope that this solved the problem. Have a good writing.

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I can't comment. So... Has anyone looked at the inside of feathers?? They are hollow with crisscross support. Any metal can also be formed this way. Basically you bubble air or other gas through the middle of the steel while it solidifies. Do this on the same scale as the feather structure. If you put too much air you get metallic foam.

So, more air less steel and weight.

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    $\begingroup$ Welcome to Worldbuilding, Kinari. This isn't a bad answer but needs to be expanded. For instance, how does the sacrifice of weight in metallic foam impact strength? Can the wing still hold (and displace) the amount of air that would allow for flight? Don't worry about mentioning that you can't comment as this is the bones of a reasonable answer to the question but it needs to be expanded more to get upvotes (which will allow you to comment). $\endgroup$ – Tim B II Jun 20 '18 at 2:05
  • $\begingroup$ Thanks for the answer! Please also take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox (both of which require 5 rep to post on) useful. Have fun! $\endgroup$ – FoxElemental Jun 20 '18 at 20:13

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