A bird or bat doesn't seem likely. The track is too thin. Even the smallest bat would have to be awfully high above the camera... and thus out of the headlight beams. Also there are squiggles and a tight loop. It doesn't make sense for a bird or bat to follow that kind of path.
I think we're back to plant parts. I've realized that the camera was positioned in the gore (triangular piece of land) between the two roads. Not on the side of Dunbar Road.
Which means the car headlights must have been in the right position for longer than I thought. Once the car turned that slight left corner, they had a straight shot at the camera... and the air above the camera.
In addition to floating seeds (or pappus if you please) it might be a leaf from one of the nearby trees on the side of Dunbar Road. Falling leaves can take a complex path.
Also, if we're thinking in 3D, the thinner part of the track might mark a time when the leaf was higher above the camera and the thicker part might mark when the leaf had fallen closer to the camera.
Questions:
What type of trees are those?
How big are the leaves on those trees?
Could it be a part of a leaf?
Could a leaf have drifted all the way from the side of Dunbar Road to the air above the camera? Kind of a long shot.
At this point my preferred explanation is that this streak was caused by a drifting cattail seed. In that case the thin part of the track marks the point when the car was most distant and the thicker part of the track marks the point when the car was closer. The illumination would be dimmer and brighter, in other words.
The weather report says wind speed was zero. We shouldn't take that too literally. We should also consider that passing cars would disturb the air. There are no cars going past at the moment this long exposure was taken, but couldn't the wind from a passing car lift cattail seeds into the air and leave very slight vortexes?
I think that there may have been very slight air currents, vortexes... whatever... and the seed (pappus) was drifting in a complex pattern not far above the camera. It wouldn't have to be in best focus.
I've captured this new frame which shows another part of the pondside plants. Are these cattails?
