Fine-Feathered Friends

April 18, 2024 6:43 PM

The two flat “blades” of a feather on either side of the main shaft are called vanes. In living birds that fly, the feathers that arise from the hand, known as the primaries, have asymmetrical vanes: the leading vane is narrower than the trailing one. It stood to reason that vane asymmetry was important for flight. And because fossils of Microraptor and its kin show asymmetrical feathers, some researchers argued, these animals must have been able to fly.

Recent work by flight biomechanics experts, including me, has overturned this received wisdom about feather vane asymmetry. Our research shows that feather shape is largely optimized to allow the feather to twist and bend in sophisticated ways that greatly enhance flight performance. Merely being anatomically asymmetrical doesn’t mean much. What matters is that the feather is aerodynamically asymmetrical, and for this to be the case, the vane asymmetry must be at least three to one—that is, the trailing blade needs to be three times wider than the leading one. Below this ratio, the feather twists in a destabilizing rather than stabilizing way during flight.

Scientific American: Why Feathers Are One of Evolution’s Cleverest Inventions [includes helpful illustrations -- and some truly stunning 4K+ photography]

Direct links to the images for all your wallpapering needs:

"Bar-tailed Godwits undertake the longest nonstop migration of any land bird in the world." [2950x1967]

"Feathers, such as those of the Lesser Flamingo shown here, are products of hundreds of millions of years of evolution." [5015x3348]

"The wing of the Greater Prairie-Chicken, a type of grouse, has a slotted tip that helps the bird burst into flight when startled." [4725x3150]

"The Barn Owl‘s primary feathers have features that allow this bird of prey to fly silently." [2377x3566]

"The extremely stiff feathers of hummingbirds such as Anna’s Hummingbird help to support their distinctive, hovering flight." [1628x1267]

[note: shows preserved specimens] "Long display feathers may be present on the wings, as happens in the Standard-winged Nightjar (left) and Pennant-winged Nightjar (right center). But they usually grow on the lower back and tail, which minimizes any negative impact on flight, as in the Stephanie’s Astrapia (left center) and Resplendent Quetzal (right)." [3607x4840]

posted by Rhaomi (18 comments total)

Fucking birds

How do they work?

One of my dogs is losing her mind over birds. She doesn't seem to got that they can fly, and she can't...

Hollow bones and shit? Evolutionary cool shit.
posted by Windopaene at 7:17 PM on April 18 [6 favorites]

Owls achieve this stealth with a few different feather adaptations. To start, their feathers have a “velvety” surface that silences them when they move against one another. More important, the feathers on the leading edge of an owl’s wing have a set of comblike structures, whereas those on the trailing edge have fluffy fringes. The leading-edge comb stirs the air in a specific way called micro vorticity. These tiny, swirling streams of air cause the main flow to stick to the wing. In aerodynamic speak, we say the combs “inject vorticity into the boundary layer.” When this modified flow then passes through the trailing-edge fringes, the net result is a wake that contains no coherent waves of linear pressure and therefore no sound. Put another way, there are no vibrations from the interactions between feathers and the air capable of producing sound.

WAT
posted by rrrrrrrrrt at 7:28 PM on April 18 [12 favorites]

That is an astonishing opening paragraph. I can't wait to read the rest of it.
posted by clawsoon at 7:34 PM on April 18

Hollow bones and shit? Evolutionary cool shit.

The thing I struggle to understand or visualize is the intermediate steps, and over the course of millions of years there must have been approximately that many. All those intermediate evolutionary steps must have provided some sort of selection-pressure advantage, but what? How did that play out in practice, and how many possible futures were cut off because their agents couldn’t survive long enough to bone the next generation of possibilities into being? It’s all pretty wild to consider, even if we might never really know.
posted by mhoye at 7:39 PM on April 18 [2 favorites]

“There is an art, it says, or rather, a knack to flying. The knack lies in learning how to throw yourself at the ground and miss. … Clearly, it is this second part, the missing, which presents the difficulties.”
― Douglas Adams, Life, the Universe and Everything
posted by knoxg at 7:43 PM on April 18 [2 favorites]

I do long for a day when we don’t use agentive language to talk about evolution, but the title wouldn’t be as catchy: We Should Lose Our Shit Over The Incredibly Specialized Structures Present In Feathers Precisely Because They Are NOT The Product Of Invention But Rather The Undirected And Continual Chaos Of Recombination, Transcription Errors, Other Mutations, And Epigenetic Grab-Bag Effects Resulting In Differential Survival and Reproduction Rates For Bird Ancestors Over Tens Of Millions Of Years (OR, No Pigeon Is Driving The Bus)
posted by rrrrrrrrrt at 7:49 PM on April 18 [15 favorites]

Owls are crazy. silent Death from above.

And bats? (Who aren't birds but act like them and might have Rabies?). (Ms. Windo thought she might have gotten bitten by a bat up in BC, and did the wholes Rabies thing. Not fun)

Our neighbors have some big trees. This morning the crows all decided these were the trees they wanted to chill in. There was some apparent swooping going on in the diagonal neighbors yard, maybe there was some meat there. We had a big rabbit go down in our yard a while ago. Dogs noticed it before I did. Was still breathing, so had to wait to let it go before I but it in a garbage bag. It was in bad shape and we do have coyotes roaming the neighborhood. Still was terrible...

But this murder had about 30 crows, all looking for branches to land on, (higher is better), and cawing and fucking with each other...

Birbs
posted by Windopaene at 8:27 PM on April 18 [2 favorites]

Boeing 777 with a 213-foot wingspan and one of the most powerful jet engines in the world.

Well, actually, it has two.
posted by PresidentOfDinosaurs at 9:01 PM on April 18 [1 favorite]

Also, this is a great article. Smooth writing, just enough detail to leave one craving more, and those pictures! Thanks for sharing it.
posted by PresidentOfDinosaurs at 9:19 PM on April 18

I do indeed find solace knowing that owl gets scritches and walks.
posted by Grandysaur at 12:08 AM on April 19 [1 favorite]

I am pleased to learn about both the Resplendent Quetzal and the cloud forests in which it lives.
posted by betaray at 5:29 AM on April 19 [2 favorites]

I can’t look at feathers and not thing about what kind of fly fishing fly I could tie. I’ve collected goose feathers from my local park for the biots
posted by xtian at 5:56 AM on April 19

Great article. Since we have such a broad cross-section of folks on MF I’ll ask something I was recently wondering about birds: do we have an idea how many species survived to be the ancestors of all birds? I assume some kind of sequencing magic plus more math than I possess allows a reasonable estimate? It’s not the kind of question that’s easy to answer with googling (or kagi-ing).
posted by Gilgamesh's Chauffeur at 6:26 AM on April 19 [1 favorite]

One of the most fascinating articles I've read in a long time. The discussion of flight bio-mechanics was particularity interesting. Thanks so much for sharing, Rhaomi!
posted by JonathanB at 1:09 PM on April 19

As of 2018, the science seemed to be that only 5 bird lineages survived, all initially ground dwelling, but apparently there's been some pushback on that number, basically whether some of the gray bars in this chart split before Chicxulub hit rather than right after.
posted by tavella at 2:27 PM on April 19 [3 favorites]

All those intermediate evolutionary steps must have provided some sort of selection-pressure advantage, but what?

Insulation, display, and even flight.

Early pennaraptorans such as Microraptor didn’t have aerodynamically asymmetrical feathers. But that doesn’t mean they couldn’t fly. The tendency to twist (whether in a stabilizing or a destabilizing fashion) is only relevant if the feathers are separated enough to do so. Keeping feathers in a wing tip tight and overlapping makes them stable, even if they’re not asymmetrical.

posted by ChurchHatesTucker at 3:08 PM on April 19

Great article.

And I see that Scientific American has FINALLY, apparently, put their entire archive online for subscribers, a group which is about to include me.
posted by neuron at 9:35 PM on April 19

Alhamdulillah!
posted by rabia.elizabeth at 6:30 AM on April 20