Rules of Summer by Shaun Tan

It's Tan's odd & creepy little drawings that make me pick up his books.
This one is about two brothers and how they spent a summer and the rules the older brother made up.
Every two page spread is a story in itself and I wish I knew the complete story. Like the "Never ruin a perfect plan". (This one is my favorite.) I'd love to read the plan behind this picture.
What was the crow/black bird? Was it really just winter? Or was it something else always watching the boys? I felt like everything bad came from that stupid bird, but then again as children we hate the thought that summer is ending and winter will soon be here.
As a mom of two boys, I felt sad at "Never ask for a reason."
Read this book twice, first time read it, second time take your time and imagine the story behind the pictures.
I'm not sure I'd let the little ones read this.