How was this work conceived?

I know what flying is like because I dreamed of it many times. I started drawing these birds years ago but never of that scale.
I usually start by drawing very small sketches and test dozens of colors for each pattern.
This drawing was made to the maximum size my table would support, this is the largest I've done so far and will probably do until I move to a bigger place.

What is your favourite window?

The window of my bathroom from which I see the birds flying over Brussels.