What are the major themes in The Humming Bird Tree by Ian McDonald?

Power vs Powerlessness Alan in the book had tremendous power but he sought not to use it. Kaiser and his sister were powerless but the took all the opportunities given by Alan(not using his power) and promoted themselves to powerul over the young white boy.

Prejudice (leave what you believe)

Racism The parents hated the little native for friends with their "handsome and beautiful" whithe children. Their children were never to be seen playing with these children. It can be alluded to the fact that Kaiser and jaillin wer not allowed to attend Alan's party because the were of different race. Friendship Alan, Kaiser and Jaillin had a relationship that was inceprable. The were friends no matter the looks or the different environments they came from
Themes in a humming bird tree are quite simple actually. They are class and social status, love and friendships, home environment and nature.