We used to have a flock of about 15 in our backyard in birkenhead, on aucklands north shore. them among the other introduced parrots. the damage they did to our fruit trees was negligible, and they mostly destroyed fruit we wouldn't eat any ways.
the albany chooks on the other hand, were not allowed to be uplifted from the area, and new ones were not allowed to be left there. way to eradicate them - do not let any one take them away or re home them. sometimes i wonder who the brains behind these projects really are.