Possum release unpleasant scent that is yet another indication in their existence. Also, they leave claw marks where ever they roam. If you'll find any tree branches close to the roof, trim them so that there's no spot for the possum to climb onto the roof. I needed a termite https://possumremovalmelbourne68890.wikifordummies.com/6632440/detailed_notes_on_possum_removal_melbourne