I have a problem with raccoons climbing my trees and raiding my bird feeders at night. The trees range in circumference from 12" to 18". Bringing the feeders in each night is a hassle and sometimes I forget. One solution I've seen mentioned is to wrap aluminum flashing around the trees. However, none of my trees are mature, and I need to allow for the trunks to expand. I also don't want to do anything that harms the trees (e.g. stapling/nailing the flashing to them). Can anyone suggest a good way to prevent raccoons from climbing these trees?