A few years ago my niece showed me some photographic art of flocks of birds taking off, which were basically multiple exposures showing the flight trails of all the birds massed together. They were stunning but had no details about the exact technique the photographer had used and the only thing I can remember about him now is that he was French.
These images stayed in the back of my mind for a while until I grew confident enough that I could give it a go with the one difference being that birds in flight rather than taking off would be my targets.
The photographs in this post are my results.
The first two are of thermalling Openbill Storks and the other two are of Swiftlets. All were taken over our garden here in Thailand.
The basic technique I used was to take a video and then blend the frames into a single image. I made them by first taking a video of the birds with the camera on a tripod, which meant that the trails would be smooth clean lines and also that the birds would be the only thing moving. This was easy for the Swiftlets, which are constantly scything through the air in all directions so I could more-or-less point the camera anywhere, but more tricky for the Storks as it's hard to be sure exactly where and how quickly they are going to drift.
Secondly, I used "import video frames as layers" in Photoshop, but found that it was better if I didn't use every frame so checked the option to "limit to every 5 frames" for the Storks and "every 2 frames" for the Swiftlets. Changing the blend mode to "darker colour" on every layer except the lowest then produced the trails as you see them here with just a little bit of contrast and saturation adjustment. For the Swiftlets I also toned the image for a warmer feel.
This "darker colour" blend mode works well with dark bird silhouettes against a light sky. Something like a cloud of butterflies flying against a cluttered background of branches and leaves would be a whole new level of challenge!
I think these trails add an interesting extra dimension to their already beautiful flight, which is hard to display in a still image. The Storks are particularly fascinating as the thermals they use to gain height are themselves traversing across the land so the tracks of the birds tend to be stretched out spirals rather than circles. Also, as the angle of these broad-winged birds changes the thickness of the line produced also changes giving a nice italic-style effect. The "e" for Ecency was a lucky accident!
I will definitely be trying to make more of these images. A passing flock or roosting birds bursting out of a tree are other variations with great potential.
There is also, by the way, a Myna bird in the first Swiftlet image and a fly in the second! Can you spot them?