The group behaviors of birds are fascinating to watch, from the swooping arcs of swallows to the incredible murmurations of starlings. These extruded time videos give a bit more form to those movements, tracing the paths of different birds through the sky.
Rhode Island School of Design professor Dennis Hlynsky's Small Brains on Mass project uses video imaging to show the patterns in various movements of animal groups. He explains his process on his website:
There are no digital additions to the video. They are processed by stacking a sequence of frames and adding the darkest pixels together. The frame at the beginning of the stack is dropped and the next frame in sequence is added to the end of the stack. This process is repeated until the entire video clip is rendered. I do not use time lapse in the traditional sense of the word but offer a glimpse seconds long of the paths these creatures take. I find each "flock" has a form, a rhythm, and pattern to the glyphs they leave as they perambulate.
Hlynsky's videos of starlings are especially spectacular:
But he has also tracked the paths of swallows:
And many more. Hlynsky's videos aren't just limited to birds, either. For example, here he has tracked the frenzied march of ants:
You can see all of his videos, both from his nature series and his other projects, on Vimeo.