Animals Made from 13 Circles (2016)

Im curious what the process looks like to implement this. It seems like it would be easiest to start with the animal using only perfectly(?) curved lines and then complete them into circles after the fact. Although that seems kind of pointless and I imagine they start with circles. And I guess it would hard to have a curve from a perfect circle without the circle?

I just have a hard time imagining you start with circles, lay them down (resize as needed) and continue. I mean I guess that doesnt sound so crazy after I say it... it just seems like it would add a lot of extra noise to the image that would make it much harder to draw.