Give it a strong selective pressure towards speed and a few million years and you will have your supersonic duck.

Intercontinental ballistic mallards? Just another trillion-dollar boondoggle from the military-ornithological complex.

Reverse dragooning by expelling fiery farts made of hypergolics fueled by fantastic fermentation?

Something like that is featured in Terry Pratchett's Discworld series of books. (Don't spoil the book it's in!)

GNU Terry Pratchett

There's also that Harry Potter spinoff movie in which he becomes a supersonic corpse with a farting jet-butt in order to visit some pretty redwood parks: https://www.inverse.com/article/17614-how-swiss-army-man-mad...

Something similar already happened in reality in another evolutionary chain:

https://en.wikipedia.org/wiki/Bombardier_beetle

(on a much smaller scale)

Hummingbirds go to mexico to vacation a lot more than I do. Imagine if humans had a manadatory 2000 mile trip and 6 month layover twice a year to survive.

Once you have technology that enables flapping type motion, it's opening up the applicable physics to like 6 degrees of freedom versus zero in current wing technology (fixed = 0 degree of freedom); much more complex and interesting to study.

How else will we move toward ornithopter style wings, or vehicles that can hover via wing movement.

Rotating wing aircraft have no problem hovering mid-air. All we need are a handful of breakthroughs in battery tech.

Rotating wing aircraft have problems with supersonic flight - and the wing (rotor) itself reaches supersonic much quicker than the aircraft itself, thats why helis are usually slow, compared to aircraft.

I guess “supersonic wing flapping” would have similar problems, but maybe there are more clever solutions than can be modeled, with so much degree of freedom?

And is “supersonic flapping” even possible?

I once ate duck in Paris.

That is a remarkable story...

The arctic tern flies from the north pole to the south pole.