I tried to generate that flying pattern with grasshopper by inputting their chaotic patterns that I traced as line drawings and then I started to input some flight conditions such as how they fly lower to the ground when the wind is stronger, how they migrate to north during the winter season and then comes back, conditions like that into certain points and areas where the geometry starts and ends.

After setting those conditions I run many lines over the patterns that I traced. And then I control over the strength, how far will it form and the counts .That has been my methodology for generating the geometry.