I've long had this pet theory that soaring birds have a fine vision that allows them to see thermals (warm ascending currents) directly, through changes in the air's refraction index. I've searched a bit, but no research seems to ever have considered the question. Just a wild theory, though.
Interesting. I don't think that would be possible - the technique shown here relies on a mirror to get interferometry between the two light paths. I can't see how interferometry would be available to soaring birds (between its two eyes, perhaps?). Although nature has come up with some very surprising and impressive inventions before, so I might be wrong. I would guess they're just very good at spotting the conditions…
Given that many soaring birds have fantastic eyes to find prey or carrion, they might be able to see it.