Crow collects chunks of glass in a hollow tree?
So I'm reading "Norwegian Wood" by Haruki Murakami and I came across this passage this line :"Like the way a crow collects chunks of glass in a hollow tree."In context:---"Don't be silly," said Midori. "You don't have to know anything to pass college entrance exams! All you need is a little intuition - and I have great intuition. 'Choose the correct answer from the following three.' I know immediately which one is right. My intuition's not as good as yours, so I have to learn systematic thinking to some extent. **Like the way a crow collects chunks of glass in a hollow tree.**"---I'm not sure what he's trying to say here. Is this some strange idiom I'm unfamiliar with? Crows tend to be intelligent creatures, however, I don't believe they are systematic.What do you guys think?Thanks!