I have, but you only catch them on video. You can sit looking for them for hours and you wont see a darn thing! I live on 92nd and I-25, Just a few miles from where this story takes place. I take a bunch of time-lapse video of Denver and see these things toss around. I thought they were pieces of trash or leaves blowing around in the fall wind but they dont "act" like trash since they turn so sharply go up and down and go against the wind, plus trash doesnt typically blow around that high in the air. They are not birds either, they fly too fast. Very strange looking "Things". You also see them when looking at DIA. Dont mess with them and they probably wont mess with you...