i grew up on a farm in northland. IMO the problem with the possums isn't so much that they eat the fauna, it's the fact that they are such prolific breeders so huge numbers eat alot. if their numbers are contained then they won't be such a problem. my friend has a farm at the base of the Tangihua Ranges. We would go shooting every week when the hedge apple trees were in fruit & we would shoot between 120-160 per two hour trip. it didn't matter how often we went out the numbers would always be there. the "possum runs" there looked like catle tracks there were so many.
my cousin went on a trip with 6 others to a remote area of bush between kaikohe & dargaville. they went at night, each man had a gun & 200 rounds. there were so many possums there they could hear them walking around under the trees. every man ran out of ammo & he reckons they did not get half of them! im not sure how many of you are aware of their numbers but they are simply out of control hence the need for widespread kulling with poisons etc.
as for the topic of the thread, that little one aint guna do anything so find it a new home. good luck.