Branches must be free of insects, moss, lichen etc. and selected from areas that are not near roadsides. Be aware of insecticides and herbicides that may have been directly sprayed or drifted onto trees.
It is recommended to clean branches with a dilution of bleach, rinse well and dry prior to using as perches/ chewing.
Note that resource lists from other geographical areas may refer to different species of tree that may have the same or different name to species we have here. e.g . The unsafe “Box Elder” in the U.S. is our common “Manitoba Maple”, Acer negundo .
Be safe in your selection!