I was fascinated by the crows in the scene below. Crows are purposeful creatures, and their movements are not random. They are fascinating in the way they move: almost lumbering but with an unexpected grace that suddenly emerges. So I began trying to capture some of that grace in quick sketches with a graphite pencil. (Very quick: they are constantly changing position.)
Though I knew there would be little detail in the painting, I wanted the attitude and relationships between the birds to be accurate. When I got home, I went online, and found a video showing a flock of birds interacting in a similar environment. It was lovely: I could pause the video and do a quick study of the patterns of movement. Here are a few of those sketches.
The thing that intrigued me most when I paused the video was that the images of flying birds became transparent-- I could see the background through them. This is not merely an artifact of the video-- it is actually how our brains perceive the images sent by the eye, and is the reason film and video work. Then our brain fills in the blanks, as it were, so that we think we perceive solid objects (because we are programmed to "know" they are solid).
We all experience what we think of as an ordinary transparency effect of fast motion (think of fans, or hummingbird wings). Yet we also experience other kinds of transparency, all the time. Birds flying suddenly by are good at this, and so on occasion are cats who are determined to be on that side of the door and not this. If we notice it, we think it is because it was so sudden that we weren't focusing. But that's not it. It was so sudden that the brain didn't have time to stitch it together in a seamless solid. (There are a few unfortunate people who experience this all the time, because the "stitching together" part of their brain doesn't work.)
But imagine what fun painters can have with this. If we let it happen, we can experience a lot of things this way. And paint them.