We once had a bird in our roof. I felt so sorry for the poor thing, but the funniest thing happened. The man hole was open and it must've flown into the garage, but we had no idea until my sister went into the garage. Oh my was she surprised and terrified - as was the bird. It was hilarious looking in on the whole ruckus, but I did feel badly for the bird.
Yes - a small possum in New Zealand.
It sounded like it wore hobnailed boots the way it ran around the attic space.
The animal exterminator laid poison which I am told dried the animal so nothing was left rotting in the attic.
Possums are regarded as vermin in NZ.
Living in Far North Queensland we often had possums in our roof. The worst was when one died in there. The smell was like nothing you can ever imagine. To this day I still feel sorry for (and grateful to) the animal control person who got it out!