To be a buzzard

Yesterday when I was leaving work, I saw a turkey vulture flying very low over the grassy area near the back of the parking lot; he couldn't have been more than 25 feet off the ground. This is the closest I've ever come to a TV, so I hopped in the car and drove nearer back there, trying to watch him as I went (maybe 100 yards). He was alone, as far as I could see, and I don't know if I scared him or what, but he kinda drifted back farther toward the road and away from me, still flying low. I had to keep my eye on him from crazy angles inside the car (through the windshield and the side windows and the moon roof), and in that time, the TV disappeared. I mean, he absolutely vanished. There was no place for him to hide; I didn't see him on the ground or in the small trees. He just vanished! I was bummed, both that I didn't have my camera and that I might've scared him off of some food source he'd found.

I drove away, trying to get a broader non-car-blocked view of the area, and he was still just gone. I don't know where he went, but he went there FAST.

To me, turkey vultures are both beautiful and somewhat repellent. As Linda mentioned in a comment on the Power Bird quiz post, vultures in flight are quite beautiful: large, with a broad wingspan and delicate fingerlike primary feathers spread out at the wing tips. They rarely flap their wings, instead just floating along on wind currents. Whenever Kat and I are driving somewhere and I see a turkey vulture, I always say, "Look, an eagle! Soaring majestically! ... in a circle!" It's our little birding joke, because I always used to make every large bird into an eagle to make it seem more exciting and because I'd never actually seen an eagle yet.

TVs (I've never seen a black vulture, so I'm limiting my discussion to turkey vultures) always seem to fly so slowly, preferring to drift instead of actively flap their wings to get someplace. It looks like they go where the wind takes them, stopping only when they get that scent: the scent of death. This is where the "somewhat repellent" part comes in, but still I'm fascinated. I read in one of my forensic science books that vultures (and some insects) can smell death even before it comes. What exactly is it that they smell--blood? I can understand that, because blood emits a powerful scent to a predator; but sometimes an animal's injuries are internal or he's just sick and dying, so there's no blood. How do the vultures find that animal out there in the vast expanses of a desert or a valley and thus begin their circling dance? My forensic science book didn't say how the animals and insects did it, just that they can.

How does it work? What it is about a flying vulture that can sense death miles away, float toward it on the wind, and then circle above it until (gulp) it happens?