Except the big tree and birds, we can also find two animal faces on the both sides of the tree. http://www.drspeg.com/courses/00-learning/05-gestalt.html
A possibility is a very minimalist approach - using outstanding traits / features of the band and their instruments to create a striking visual - eg. Anna's long hair and little nose paired with piano keys.
B is for Book
This geometric logo looks like it is symmetrical on both sides. Each side is a mirror of the other, with the exception of the color. the color difference creates a dimensional look.