>>2982213That's not shadow, that's bat.
The bat is illuminated by a very bright flash for a very short time (somewhere around 1/10,000 of a second), but the shutter is open for the rest of the 1/160 of a second.
Since that's a relatively short shutter speed for exposure, the bat comes out as a silhouette against the sky, but since it's too long of an overall exposure to stop motion, you get a motion blurred silhouette.
